The repeating contractile units of the MYOFIBRIL, delimited by Z bands along its length.
The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .
A giant elastic protein of molecular mass ranging from 2,993 kDa (cardiac), 3,300 kDa (psoas), to 3,700 kDa (soleus) having a kinase domain. The amino- terminal is involved in a Z line binding, and the carboxy-terminal region is bound to the myosin filament with an overlap between the counter-connectin filaments at the M line.
A powerful flexor of the thigh at the hip joint (psoas major) and a weak flexor of the trunk and lumbar spinal column (psoas minor). Psoas is derived from the Greek "psoa", the plural meaning "muscles of the loin". It is a common site of infection manifesting as abscess (PSOAS ABSCESS). The psoas muscles and their fibers are also used frequently in experiments in muscle physiology.
The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.
Contractile tissue that produces movement in animals.
A protein factor that regulates the length of R-actin. It is chemically similar, but immunochemically distinguishable from actin.
One of two types of muscle in the body, characterized by the array of bands observed under microscope. Striated muscles can be divided into two subtypes: the CARDIAC MUSCLE and the SKELETAL MUSCLE.
A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.
Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.
An actin capping protein that binds to the pointed-end of ACTIN. It functions in the presence of TROPOMYOSIN to inhibit microfilament elongation.
A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.
Muscle contraction with negligible change in the force of contraction but shortening of the distance between the origin and insertion.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
Developmental events leading to the formation of adult muscular system, which includes differentiation of the various types of muscle cell precursors, migration of myoblasts, activation of myogenesis and development of muscle anchorage.
Muscular contractions characterized by increase in tension without change in length.
A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.
Resistance and recovery from distortion of shape.
Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).
The properties, processes, and behavior of biological systems under the action of mechanical forces.
An intermediate filament protein found predominantly in smooth, skeletal, and cardiac muscle cells. Localized at the Z line. MW 50,000 to 55,000 is species dependent.
Contractile activity of the MYOCARDIUM.
A protein found in the thin filaments of muscle fibers. It inhibits contraction of the muscle unless its position is modified by TROPONIN.
Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.
The hollow, muscular organ that maintains the circulation of the blood.
A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.
An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.
The performance of dissections, injections, surgery, etc., by the use of micromanipulators (attachments to a microscope) that manipulate tiny instruments.
Acquired, familial, and congenital disorders of SKELETAL MUSCLE and SMOOTH MUSCLE.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.
The use of wings or wing-like appendages to remain aloft and move through the air.
A large class of structurally-related proteins that contain one or more LIM zinc finger domains. Many of the proteins in this class are involved in intracellular signaling processes and mediate their effects via LIM domain protein-protein interactions. The name LIM is derived from the first three proteins in which the motif was found: LIN-11, Isl1 and Mec-3.
The restriction of the MOVEMENT of whole or part of the body by physical means (RESTRAINT, PHYSICAL) or chemically by ANALGESIA, or the use of TRANQUILIZING AGENTS or NEUROMUSCULAR NONDEPOLARIZING AGENTS. It includes experimental protocols used to evaluate the physiologic effects of immobility.
Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.
Mature contractile cells, commonly known as myocytes, that form one of three kinds of muscle. The three types of muscle cells are skeletal (MUSCLE FIBERS, SKELETAL), cardiac (MYOCYTES, CARDIAC), and smooth (MYOCYTES, SMOOTH MUSCLE). They are derived from embryonic (precursor) muscle cells called MYOBLASTS.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
Sharp instruments used for puncturing or suturing.
The use of instrumentation and techniques for visualizing material and details that cannot be seen by the unaided eye. It is usually done by enlarging images, transmitted by light or electron beams, with optical or magnetic lenses that magnify the entire image field. With scanning microscopy, images are generated by collecting output from the specimen in a point-by-point fashion, on a magnified scale, as it is scanned by a narrow beam of light or electrons, a laser, a conductive probe, or a topographical probe.
Bundles of actin filaments (ACTIN CYTOSKELETON) and myosin-II that span across the cell attaching to the cell membrane at FOCAL ADHESIONS and to the network of INTERMEDIATE FILAMENTS that surrounds the nucleus.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.
A form of interference microscopy in which variations of the refracting index in the object are converted into variations of intensity in the image. This is achieved by the action of a phase plate.
The excitable plasma membrane of a muscle cell. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Elements of limited time intervals, contributing to particular results or situations.
The physical characteristics and processes of biological systems.
Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.
Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.
The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.
That phase of a muscle twitch during which a muscle returns to a resting position.
Different forms of a protein that may be produced from different GENES, or from the same gene by ALTERNATIVE SPLICING.
Refers to animals in the period of time just after birth.
A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.
The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.
The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.
Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.

Subcellular adaptation of the human diaphragm in chronic obstructive pulmonary disease. (1/1432)

Pulmonary hyperinflation impairs the function of the diaphragm in patients with chronic obstructive pulmonary disease (COPD). However, it has been recently demonstrated that the muscle can counterbalance this deleterious effect, remodelling its structure (i.e. changing the proportion of different types of fibres). The aim of this study was to investigate whether the functional impairment present in COPD patients can be associated with structural subcellular changes of the diaphragm. Twenty individuals (60+/-9 yrs, 11 COPD patients and 9 subjects with normal spirometry) undergoing thoracotomy were included. Nutritional status and respiratory function were evaluated prior to surgery. Then, small samples of the costal diaphragm were obtained and processed for electron microscopy analysis. COPD patients showed a mean forced expiratory volume in one second (FEV1) of 60+/-9% predicted, a higher concentration of mitochondria (n(mit)) in their diaphragm than controls (0.62+/-0.16 versus 0.46+/-0.16 mitochondrial transections (mt) x microm(-2), p<0.05). On the other hand, subjects with air trapping (residual volume (RV)/total lung capacity (TLC) >37%) disclosed not only a higher n(mit) (0.63+/-0.17 versus 0.43+/-0.07 mt x microm(-2), p<0.05) but shorter sarcomeres (L(sar)) than subjects without this functional abnormality (2.08+/-0.16 to 2.27+/-0.15 microm, p<0.05). Glycogen stores were similar in COPD and controls. The severity of airways obstruction (i.e. FEV1) was associated with n(mit) (r=-0.555, p=0.01), while the amount of air trapping (i.e. RV/TLC) was found to correlate with both n(mit) (r=0.631, p=0.005) and L(sar) (r=-0.526, p<0.05). Finally, maximal inspiratory pressure (PI,max) inversely correlated with n(mit) (r=-0.547, p=0.01). In conclusion, impairment in lung function occurring in patients with chronic obstructive pulmonary disease is associated with subcellular changes in their diaphragm, namely a shortening in the length of sarcomeres and an increase in the concentration of mitochondria. These changes form a part of muscle remodelling, probably contributing to a better functional muscle behaviour.  (+info)

Morphology and mechanics of tongue movement in the African pig-nosed frog Hemisus marmoratum: a muscular hydrostatic model. (2/1432)

The goal of this study was to investigate morphological adaptations associated with hydrostatic elongation of the tongue during feeding in the African pig-nosed frog Hemisus marmoratum. Whereas previous studies had suggested that the tongue of H. marmoratum elongates hydraulically, the anatomical observations reported here favour a muscular hydrostatic mechanism of tongue elongation. H. marmoratum possesses a previously undescribed compartment of the m. genioglossus (m. genioglossus dorsoventralis), which is intrinsic to the tongue and whose muscle fibres are oriented perpendicular to the long axis of the tongue. On the basis of the arrangement and orientation of muscle fibres in the m. genioglossus and m. hyoglossus, we propose a muscular hydrostatic model of tongue movement in which contraction of the m. genioglossus dorsoventralis, together with unfolding of the intrinsic musculature of the tongue, results in a doubling in tongue length. Electron micrographs of sarcomeres from resting and elongated tongues show that no special adaptations of the sarcomeres are necessary to accommodate the observed doubling in tongue length during feeding. Rather, the sarcomeres of the m. genioglossus longitudinalis are strikingly similar to those of anuran limb muscles. The ability to elongate the tongue hydrostatically, conferred by the presence of the m. genioglossus dorsoventralis, is associated with the appearance of several novel aspects of feeding behaviour in H. marmoratum. These include the ability to protract the tongue slowly, thereby increasing capture success, and the ability to aim the tongue in azimuth and elevation relative to the head. Compared with other frogs, the muscular hydrostatic system of H. marmoratum allows more precise, localized and diverse tongue movements. This may explain why the m. genioglossus of H. marmoratum is composed of a larger number of motor units than that of other frogs.  (+info)

Dynamic distribution and formation of a para-sarcomeric banding pattern of prosomes during myogenic differentiation of satellite cells in vitro. (3/1432)

Myogenesis proceeds by fusion of proliferating myoblasts into myotubes under the control of various transcription factors. In adult skeletal muscle, myogenic stem cells are represented by the satellite cells which can be cultured and differentiate in vitro. This system was used to investigate the subcellular distribution of a particular type of prosomes at different steps of the myogenic process. Prosomes constitute the MCP core of the 26S proteasomes but were first observed as subcomplexes of the untranslated mRNPs; recently, their RNase activity was discovered. A monoclonal antibody raised against the p27K subunit showed that the p27K subunit-specific prosomes move transiently into the nucleus prior to the onset of myoblast fusion into myotubes; this represents possibly one of the first signs of myoblast switching into the differentiation pathway. Prior to fusion, the prosomes containing the p27K subunit return to the cytoplasm, where they align with the gradually formed lengthwise-running desmin-type intermediate filaments and the microfilaments, co-localizing finally with the actin bundles. The prosomes progressively form discontinuous punctate structures which eventually develop a pseudo-sarcomeric banding pattern. In myotubes just formed in vitro, the formation of this pattern seems to preceed that produced by the muscle-specific sarcomeric (alpha)-actin. Interestingly, this pattern of prosomes of myotubes in terminal in vitro differentiation was very similar to that of prosomes observed in vivo in foetal and adult muscle. These observations are discussed in relation to molecular myogenesis and prosome/proteasome function.  (+info)

Correlation between myofilament response to Ca2+ and altered dynamics of contraction and relaxation in transgenic cardiac cells that express beta-tropomyosin. (4/1432)

We compared the dynamics of the contraction and relaxation of single myocytes isolated from nontransgenic (NTG) mouse hearts and from transgenic (TG-beta-Tm) mouse hearts that overexpress the skeletal isoform of tropomyosin (Tm). Compared with NTG controls, TG-beta-Tm myocytes showed significantly reduced maximal rates of contraction and relaxation with no change in the extent of shortening. This result indicated that the depression in contraction dynamics determined in TG-beta-Tm isolated hearts is intrinsic to the cells. To further investigate the effect of Tm isoform switching on myofilament activity and regulation, we measured myofilament force and ATPase rate as functions of pCa (-log of [Ca2+]). Compared with controls, force generated by myofilaments from TG-beta-Tm hearts and myofibrillar ATPase activity were both more sensitive to Ca2+. However, the shift in pCa50 (half-maximally activating pCa) caused by changing sarcomere length from 1.8 to 2.4 microm was not significantly different between NTG and TG-beta-Tm fiber preparations. To test directly whether isoform switching affected the economy of contraction, force versus ATPase rate relationships were measured in detergent-extracted fiber bundles. In both NTG and TG-beta-Tm preparations, force and ATPase rate were linear and identically correlated, which indicated that crossbridge turnover was unaffected by Tm isoform switching. However, detergent extracted fibers from TG-beta-Tm demonstrated significantly less maximum tension and ATPase activity than NTG controls. Our results provide the first evidence that the Tm isoform population modulates the dynamics of contraction and relaxation of single myocytes by a mechanism that does not alter the rate-limiting step of crossbridge detachment. Our results also indicate that differences in sarcomere-length dependence of activation between cardiac and skeletal muscle are not likely due to differences in the isoform population of Tm.  (+info)

Myofibrillogenesis in the developing chicken heart: assembly of Z-disk, M-line and the thick filaments. (5/1432)

Myofibrillogenesis in situ was investigated by confocal microscopy of immunofluorescently labelled whole mount preparations of early embryonic chicken heart rudiments. The time-course of incorporation of several components into myofibrils was compared in triple-stained specimens, taken around the time when beating starts. All sarcomeric proteins investigated so far were already expressed before the first contractions and myofibril assembly happened within a few hours. No typical stress fibre-like structures or premyofibrils, structures observed in cultured cardiomyocytes, could be detected during myofibrillogenesis in the heart. Sarcomeric proteins like (&agr;)-actinin, titin and actin were found in a defined localisation pattern even in cardiomyocytes that did not yet contain myofibrils, making up dense body-like structures. As soon as the heart started to beat, all myofibrillar proteins were already located at their exact position in the sarcomere. The maturation of the sarcomeres was characterised by a short delay in the establishment of the pattern for M-line epitopes of titin with respect to Z-disk epitopes and the incorporation of the M-line component myomesin, which preceded that of myosin binding protein-C. Thus dense body-like structures, made up of titin, (&agr;)-actinin and actin filaments serve as the first organised complexes also during myofibrillogenesis in situ and titin functions as a ruler for sarcomere assembly as soon as its C termini have become localised. We suggest that assembly of thin and thick filament occurs independently during myofibrillogenesis in situ and that myomesin might be important for integrating thick filaments with the M-line end of titin.  (+info)

Different domains of the M-band protein myomesin are involved in myosin binding and M-band targeting. (6/1432)

Myomesin is a 185-kDa protein located in the M-band of striated muscle where it interacts with myosin and titin, possibly connecting thick filaments with the third filament system. By using expression of epitope-tagged myomesin fragments in cultured cardiomyocytes and biochemical binding assays, we could demonstrate that the M-band targeting activity and the myosin-binding site are located in different domains of the molecule. An N-terminal immunoglobulin-like domain is sufficient for targeting to the M-band, but solid-phase overlay assays between individual N-terminal domains and the thick filament protein myosin revealed that the unique head domain contains the myosin-binding site. When expressed in cardiomyocytes, the head domains of rat and chicken myomesin showed species-specific differences in their incorporation pattern. The head domain of rat myomesin localized to a central area within the A-band, whereas the head domain of chicken myomesin was diffusely distributed in the cytoplasm. We therefore conclude that the head domain of myomesin binds to myosin but that this affinity is not sufficient for the restriction of the domain to the M-band in vivo. Instead, the neighboring immunoglobulin-like domain is essential for the precise incorporation of myomesin into the M-band, possibly because of interaction with a yet unknown protein of the sarcomere.  (+info)

Effect of rate of distraction on loss of range of joint movement, muscle stiffness, and intramuscular connective tissue content during surgical limb-lengthening: a study in the rabbit. (7/1432)

Surgical lengthening of limbs often results in loss of range of joint movement and this has been shown to be associated with an increase in passive tension and an increase in collagen content of the muscles. In this study, we have investigated the length/tension properties and the connective tissue component of muscle distracted at three different rates in order to determine whether low rates of distraction would enable the connective tissue component, as well as the contractile component (number of serial sarcomeres), to adapt more completely to the increased functional length of the muscle and thus lead to improved range of joint movement. It was found that loss of range of movement varied with rate of distraction. At the low rate, there was no change in the passive tension or collagen content compared to muscles from sham-operated animals, and range of movement was significantly greater than at the other rates. At the medium rate, although the muscles showed good adaptation in terms of serial sarcomere number, passive tension and collagen content was increased and range of movement reduced, indicating that changes in the connective tissue component are important factors in loss of joint movement. In the case of muscle distracted at a high rate, failure of the muscle fibres to add on sufficient sarcomeres, combined with changes in the connective tissue, resulted in almost total loss of joint movement.  (+info)

Cross bridge-dependent activation of contraction in cardiac myofibrils at low pH. (8/1432)

Striated muscle contracts in the absence of calcium at low concentrations of MgATP ([MgATP]), and this has been termed rigor activation because rigor cross bridges attach and activate adjacent actin sites. This process is well characterized in skeletal muscle but not in cardiac muscle. Rigor cross bridges are also thought to increase calcium binding to troponin C and play a synergistic role in activation. We tested the hypothesis that cross bridge-dependent activation results in an increase in contractile activity at normal and low pH values. Myofibrillar ATPase activity was measured as a function of pCa and [MgATP] at pH 7.0, and the data showed that, at pCa values of >/=5.5, there was a biphasic relationship between activity and [MgATP]. Peak activity occurred at 10-50 microM MgATP, and [MgATP] for peak activity was lower with increased pCa. The ATPase activity of rat cardiac myofibrils as a function of [MgATP] at a pCa of 9.0 was measured at several pH levels (pH 5.4-7.0). The ATPase activity as a function of [MgATP] was biphasic with a maximum at 8-10 microM MgATP. Lower pH did not result in a substantial decrease in myofibrillar ATPase activity even at pH 5.4. The extent of shortening, as measured by Z-line spacing, was greatest at 8 microM MgATP and less at both lower and higher [MgATP], and this response was observed at all pH levels. These studies suggest that the peak ATPase activity associated with low [MgATP] was coupled to sarcomere shortening. These results support the hypothesis that cross bridge-dependent activation of contraction may be responsible for contracture in the ischemic heart.  (+info)

A sarcomere is the basic contractile unit in a muscle fiber, and it's responsible for generating the force necessary for muscle contraction. It is composed of several proteins, including actin and myosin, which slide past each other to shorten the sarcomere during contraction. The sarcomere extends from one Z-line to the next in a muscle fiber, and it is delimited by the Z-discs where actin filaments are anchored. Sarcomeres play a crucial role in the functioning of skeletal, cardiac, and smooth muscles.

Myofibrils are the basic contractile units of muscle fibers, composed of highly organized arrays of thick and thin filaments. They are responsible for generating the force necessary for muscle contraction. The thick filaments are primarily made up of the protein myosin, while the thin filaments are mainly composed of actin. Myofibrils are surrounded by a membrane called the sarcolemma and are organized into repeating sections called sarcomeres, which are the functional units of muscle contraction.

Connectin is also known as titin, which is a giant protein that plays a crucial role in the elasticity and stiffness of muscle fibers. It is the largest protein in humans, spanning half the length of a muscle cell's sarcomere, the basic unit of muscle contraction. Connectin/titin has several domains with different functions, including binding to other proteins, regulating muscle contraction, and signaling within the muscle cell. Mutations in the connectin/titin gene have been associated with various forms of muscular dystrophy and cardiomyopathy.

The psoas muscles are a pair of muscles that are located in the lower lumbar region of the spine and run through the pelvis to attach to the femur (thigh bone). They are deep muscles, meaning they are located close to the body's core, and are surrounded by other muscles, bones, and organs.

The psoas muscles are composed of two separate muscles: the psoas major and the psoas minor. The psoas major is the larger of the two muscles and originates from the lumbar vertebrae (T12 to L5) and runs through the pelvis to attach to the lesser trochanter of the femur. The psoas minor, which is smaller and tends to be absent in some people, originates from the lower thoracic vertebrae (T12) and upper lumbar vertebrae (L1-L3) and runs down to attach to the iliac fascia and the pectineal line of the pubis.

The primary function of the psoas muscles is to flex the hip joint, which means they help to bring the knee towards the chest. They also play a role in stabilizing the lumbar spine and pelvis during movement. Tightness or weakness in the psoas muscles can contribute to lower back pain, postural issues, and difficulty with mobility and stability.

Muscle proteins are a type of protein that are found in muscle tissue and are responsible for providing structure, strength, and functionality to muscles. The two major types of muscle proteins are:

1. Contractile proteins: These include actin and myosin, which are responsible for the contraction and relaxation of muscles. They work together to cause muscle movement by sliding along each other and shortening the muscle fibers.
2. Structural proteins: These include titin, nebulin, and desmin, which provide structural support and stability to muscle fibers. Titin is the largest protein in the human body and acts as a molecular spring that helps maintain the integrity of the sarcomere (the basic unit of muscle contraction). Nebulin helps regulate the length of the sarcomere, while desmin forms a network of filaments that connects adjacent muscle fibers together.

Overall, muscle proteins play a critical role in maintaining muscle health and function, and their dysregulation can lead to various muscle-related disorders such as muscular dystrophy, myopathies, and sarcopenia.

A muscle is a soft tissue in our body that contracts to produce force and motion. It is composed mainly of specialized cells called muscle fibers, which are bound together by connective tissue. There are three types of muscles: skeletal (voluntary), smooth (involuntary), and cardiac. Skeletal muscles attach to bones and help in movement, while smooth muscles are found within the walls of organs and blood vessels, helping with functions like digestion and circulation. Cardiac muscle is the specific type that makes up the heart, allowing it to pump blood throughout the body.

Actinin is a protein that belongs to the family of actin-binding proteins. It plays an important role in the organization and stability of the cytoskeleton, which is the structural framework of a cell. Specifically, actinin crosslinks actin filaments into bundles or networks, providing strength and rigidity to the cell structure. There are several isoforms of actinin, with alpha-actinin and gamma-actinin being widely studied. Alpha-actinin is found in the Z-discs of sarcomeres in muscle cells, where it helps anchor actin filaments and maintains the structural integrity of the muscle. Gamma-actinin is primarily located at cell-cell junctions and participates in cell adhesion and signaling processes.

Striated muscle, also known as skeletal or voluntary muscle, is a type of muscle tissue that is characterized by the presence of distinct light and dark bands, or striations, when viewed under a microscope. These striations correspond to the arrangement of sarcomeres, which are the functional units of muscle fibers.

Striated muscle is under voluntary control, meaning that it is consciously activated by signals from the nervous system. It is attached to bones via tendons and is responsible for producing movements of the body. Striated muscle fibers are multinucleated, meaning that they contain many nuclei, and are composed of numerous myofibrils, which are rope-like structures that run the length of the fiber.

The myofibrils are composed of thick and thin filaments that slide past each other to cause muscle contraction. The thick filaments are made up of the protein myosin, while the thin filaments are composed of actin, tropomyosin, and troponin. When a nerve impulse arrives at the muscle fiber, it triggers the release of calcium ions from the sarcoplasmic reticulum, which bind to troponin and cause a conformational change that exposes the binding sites on actin for myosin. The myosin heads then bind to the actin filaments and pull them towards the center of the sarcomere, causing the muscle fiber to shorten and contract.

Muscle contraction is the physiological process in which muscle fibers shorten and generate force, leading to movement or stability of a body part. This process involves the sliding filament theory where thick and thin filaments within the sarcomeres (the functional units of muscles) slide past each other, facilitated by the interaction between myosin heads and actin filaments. The energy required for this action is provided by the hydrolysis of adenosine triphosphate (ATP). Muscle contractions can be voluntary or involuntary, and they play a crucial role in various bodily functions such as locomotion, circulation, respiration, and posture maintenance.

Skeletal muscle, also known as striated or voluntary muscle, is a type of muscle that is attached to bones by tendons or aponeuroses and functions to produce movements and support the posture of the body. It is composed of long, multinucleated fibers that are arranged in parallel bundles and are characterized by alternating light and dark bands, giving them a striped appearance under a microscope. Skeletal muscle is under voluntary control, meaning that it is consciously activated through signals from the nervous system. It is responsible for activities such as walking, running, jumping, and lifting objects.

Skeletal muscle fibers, also known as striated muscle fibers, are the type of muscle cells that make up skeletal muscles, which are responsible for voluntary movements of the body. These muscle fibers are long, cylindrical, and multinucleated, meaning they contain multiple nuclei. They are surrounded by a connective tissue layer called the endomysium, and many fibers are bundled together into fascicles, which are then surrounded by another layer of connective tissue called the perimysium.

Skeletal muscle fibers are composed of myofibrils, which are long, thread-like structures that run the length of the fiber. Myofibrils contain repeating units called sarcomeres, which are responsible for the striated appearance of skeletal muscle fibers. Sarcomeres are composed of thick and thin filaments, which slide past each other during muscle contraction to shorten the sarcomere and generate force.

Skeletal muscle fibers can be further classified into two main types based on their contractile properties: slow-twitch (type I) and fast-twitch (type II). Slow-twitch fibers have a high endurance capacity and are used for sustained, low-intensity activities such as maintaining posture. Fast-twitch fibers, on the other hand, have a higher contractile speed and force generation capacity but fatigue more quickly and are used for powerful, explosive movements.

Tropomodulin is a protein that plays a crucial role in the regulation of actin filament length and structure in muscle and non-muscle cells. It is located at the pointed ends of the actin filaments, where it binds and caps the filament, preventing the addition or loss of actin subunits. This helps maintain the stability and integrity of the cytoskeleton. Tropomodulin also interacts with other proteins, such as troponin and tropomyosin, to regulate muscle contraction. Mutations in the tropomodulin gene have been associated with certain inherited cardiac disorders, including hypertrophic cardiomyopathy and dilated cardiomyopathy.

Myosins are a large family of motor proteins that play a crucial role in various cellular processes, including muscle contraction and intracellular transport. They consist of heavy chains, which contain the motor domain responsible for generating force and motion, and light chains, which regulate the activity of the myosin. Based on their structural and functional differences, myosins are classified into over 35 classes, with classes II, V, and VI being the most well-studied.

Class II myosins, also known as conventional myosins, are responsible for muscle contraction in skeletal, cardiac, and smooth muscles. They form filaments called thick filaments, which interact with actin filaments to generate force and movement during muscle contraction.

Class V myosins, also known as unconventional myosins, are involved in intracellular transport and organelle positioning. They have a long tail that can bind to various cargoes, such as vesicles, mitochondria, and nuclei, and a motor domain that moves along actin filaments to transport the cargoes to their destinations.

Class VI myosins are also unconventional myosins involved in intracellular transport and organelle positioning. They have two heads connected by a coiled-coil tail, which can bind to various cargoes. Class VI myosins move along actin filaments in a unique hand-over-hand motion, allowing them to transport their cargoes efficiently.

Overall, myosins are essential for many cellular functions and have been implicated in various diseases, including cardiovascular diseases, neurological disorders, and cancer.

The myocardium is the middle layer of the heart wall, composed of specialized cardiac muscle cells that are responsible for pumping blood throughout the body. It forms the thickest part of the heart wall and is divided into two sections: the left ventricle, which pumps oxygenated blood to the rest of the body, and the right ventricle, which pumps deoxygenated blood to the lungs.

The myocardium contains several types of cells, including cardiac muscle fibers, connective tissue, nerves, and blood vessels. The muscle fibers are arranged in a highly organized pattern that allows them to contract in a coordinated manner, generating the force necessary to pump blood through the heart and circulatory system.

Damage to the myocardium can occur due to various factors such as ischemia (reduced blood flow), infection, inflammation, or genetic disorders. This damage can lead to several cardiac conditions, including heart failure, arrhythmias, and cardiomyopathy.

The actin cytoskeleton is a complex, dynamic network of filamentous (threadlike) proteins that provides structural support and shape to cells, allows for cell movement and division, and plays a role in intracellular transport. Actin filaments are composed of actin monomers that polymerize to form long, thin fibers. These filaments can be organized into different structures, such as stress fibers, which provide tension and support, or lamellipodia and filopodia, which are involved in cell motility. The actin cytoskeleton is constantly remodeling in response to various intracellular and extracellular signals, allowing for changes in cell shape and behavior.

An isotonic contraction in physiology and medicine refers to a type of muscle contraction where the muscle shortens while maintaining a constant tension. "Isotonic" comes from two Greek words: "iso," meaning equal, and "tonos," meaning tone or tension. During an isotonic contraction, the force generated by the muscle remains constant even as it changes length.

In the context of exercise and physiology, isotonic contractions are often discussed in relation to weightlifting or resistance training exercises. For example, when you lift a dumbbell and then lower it in a controlled manner, your muscles are performing isotonic contractions. The tension in the muscle remains relatively constant throughout the range of motion, even though the length of the muscle changes as you lift and lower the weight.

It's worth noting that there is some debate among experts about the precise definition and classification of different types of muscle contractions, including isotonic contractions. Some sources may use slightly different definitions or terminology depending on the context and their specific area of expertise.

Electron microscopy (EM) is a type of microscopy that uses a beam of electrons to create an image of the sample being examined, resulting in much higher magnification and resolution than light microscopy. There are several types of electron microscopy, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), and reflection electron microscopy (REM).

In TEM, a beam of electrons is transmitted through a thin slice of the sample, and the electrons that pass through the sample are focused to form an image. This technique can provide detailed information about the internal structure of cells, viruses, and other biological specimens, as well as the composition and structure of materials at the atomic level.

In SEM, a beam of electrons is scanned across the surface of the sample, and the electrons that are scattered back from the surface are detected to create an image. This technique can provide information about the topography and composition of surfaces, as well as the structure of materials at the microscopic level.

REM is a variation of SEM in which the beam of electrons is reflected off the surface of the sample, rather than scattered back from it. This technique can provide information about the surface chemistry and composition of materials.

Electron microscopy has a wide range of applications in biology, medicine, and materials science, including the study of cellular structure and function, disease diagnosis, and the development of new materials and technologies.

Muscle development, also known as muscle hypertrophy, refers to the increase in size and mass of the muscles through a process called myofiber growth. This is primarily achieved through resistance or strength training exercises that cause micro-tears in the muscle fibers, leading to an inflammatory response and the release of hormones that promote muscle growth. As the muscles repair themselves, they become larger and stronger than before. Proper nutrition, including adequate protein intake, and rest are also essential components of muscle development.

It is important to note that while muscle development can lead to an increase in strength and muscular endurance, it does not necessarily result in improved athletic performance or overall fitness. A well-rounded exercise program that includes cardiovascular activity, flexibility training, and resistance exercises is recommended for optimal health and fitness outcomes.

Isometric contraction is a type of muscle activation where the muscle contracts without any change in the length of the muscle or movement at the joint. This occurs when the force generated by the muscle matches the external force opposing it, resulting in a balanced state with no visible movement. It is commonly experienced during activities such as holding a heavy object in static position or trying to push against an immovable object. Isometric contractions are important in maintaining posture and providing stability to joints.

"Rana temporaria" is the scientific name for the common European frog, also known as the grass frog. It's a widespread species found throughout Europe and into western Asia. These frogs are typically brown or green in color with darker spots, and they can change their color to some extent based on their environment. They are semi-aquatic, spending time both in water and on land, and are known for their distinctive mating call.

However, if you're looking for a medical definition, there isn't one for "Rana temporaria." The term is strictly biological and refers to this specific species of frog.

In medicine, elasticity refers to the ability of a tissue or organ to return to its original shape after being stretched or deformed. This property is due to the presence of elastic fibers in the extracellular matrix of the tissue, which can stretch and recoil like rubber bands.

Elasticity is an important characteristic of many tissues, particularly those that are subjected to repeated stretching or compression, such as blood vessels, lungs, and skin. For example, the elasticity of the lungs allows them to expand and contract during breathing, while the elasticity of blood vessels helps maintain normal blood pressure by allowing them to expand and constrict in response to changes in blood flow.

In addition to its role in normal physiology, elasticity is also an important factor in the diagnosis and treatment of various medical conditions. For example, decreased elasticity in the lungs can be a sign of lung disease, while increased elasticity in the skin can be a sign of aging or certain genetic disorders. Medical professionals may use techniques such as pulmonary function tests or skin biopsies to assess elasticity and help diagnose these conditions.

Cardiac myocytes are the muscle cells that make up the heart muscle, also known as the myocardium. These specialized cells are responsible for contracting and relaxing in a coordinated manner to pump blood throughout the body. They differ from skeletal muscle cells in several ways, including their ability to generate their own electrical impulses, which allows the heart to function as an independent rhythmical pump. Cardiac myocytes contain sarcomeres, the contractile units of the muscle, and are connected to each other by intercalated discs that help coordinate contraction and ensure the synchronous beating of the heart.

Biomechanics is the application of mechanical laws to living structures and systems, particularly in the field of medicine and healthcare. A biomechanical phenomenon refers to a observable event or occurrence that involves the interaction of biological tissues or systems with mechanical forces. These phenomena can be studied at various levels, from the molecular and cellular level to the tissue, organ, and whole-body level.

Examples of biomechanical phenomena include:

1. The way that bones and muscles work together to produce movement (known as joint kinematics).
2. The mechanical behavior of biological tissues such as bone, cartilage, tendons, and ligaments under various loads and stresses.
3. The response of cells and tissues to mechanical stimuli, such as the way that bone tissue adapts to changes in loading conditions (known as Wolff's law).
4. The biomechanics of injury and disease processes, such as the mechanisms of joint injury or the development of osteoarthritis.
5. The use of mechanical devices and interventions to treat medical conditions, such as orthopedic implants or assistive devices for mobility impairments.

Understanding biomechanical phenomena is essential for developing effective treatments and prevention strategies for a wide range of medical conditions, from musculoskeletal injuries to neurological disorders.

Desmin is a type of intermediate filament protein that is primarily found in the cardiac and skeletal muscle cells, as well as in some types of smooth muscle cells. It is an important component of the cytoskeleton, which provides structural support to the cell and helps maintain its shape. Desmin plays a crucial role in maintaining the integrity of the sarcomere, which is the basic contractile unit of the muscle fiber. Mutations in the desmin gene can lead to various forms of muscular dystrophy and other inherited muscle disorders.

Myocardial contraction refers to the rhythmic and forceful shortening of heart muscle cells (myocytes) in the myocardium, which is the muscular wall of the heart. This process is initiated by electrical signals generated by the sinoatrial node, causing a wave of depolarization that spreads throughout the heart.

During myocardial contraction, calcium ions flow into the myocytes, triggering the interaction between actin and myosin filaments, which are the contractile proteins in the muscle cells. This interaction causes the myofilaments to slide past each other, resulting in the shortening of the sarcomeres (the functional units of muscle contraction) and ultimately leading to the contraction of the heart muscle.

Myocardial contraction is essential for pumping blood throughout the body and maintaining adequate circulation to vital organs. Any impairment in myocardial contractility can lead to various cardiac disorders, such as heart failure, cardiomyopathy, and arrhythmias.

Tropomyosin is a protein that plays a crucial role in muscle contraction. It is a long, thin filamentous protein that runs along the length of actin filaments in muscle cells, forming part of the troponin-tropomyosin complex. This complex regulates the interaction between actin and myosin, which are the other two key proteins involved in muscle contraction.

In a relaxed muscle, tropomyosin blocks the myosin-binding sites on actin, preventing muscle contraction from occurring. When a signal is received to contract, calcium ions are released into the muscle cell, which binds to troponin and causes a conformational change that moves tropomyosin out of the way, exposing the myosin-binding sites on actin. This allows myosin to bind to actin and generate force, leading to muscle contraction.

Tropomyosin is composed of two alpha-helical chains that wind around each other in a coiled-coil structure. There are several isoforms of tropomyosin found in different types of muscle cells, including skeletal, cardiac, and smooth muscle. Mutations in the genes encoding tropomyosin have been associated with various inherited muscle disorders, such as hypertrophic cardiomyopathy and distal arthrogryposis.

Actin is a type of protein that forms part of the contractile apparatus in muscle cells, and is also found in various other cell types. It is a globular protein that polymerizes to form long filaments, which are important for many cellular processes such as cell division, cell motility, and the maintenance of cell shape. In muscle cells, actin filaments interact with another type of protein called myosin to enable muscle contraction. Actins can be further divided into different subtypes, including alpha-actin, beta-actin, and gamma-actin, which have distinct functions and expression patterns in the body.

I believe there may be some confusion in your question. "Rabbits" is a common name used to refer to the Lagomorpha species, particularly members of the family Leporidae. They are small mammals known for their long ears, strong legs, and quick reproduction.

However, if you're referring to "rabbits" in a medical context, there is a term called "rabbit syndrome," which is a rare movement disorder characterized by repetitive, involuntary movements of the fingers, resembling those of a rabbit chewing. It is also known as "finger-chewing chorea." This condition is usually associated with certain medications, particularly antipsychotics, and typically resolves when the medication is stopped or adjusted.

Mechanical stress, in the context of physiology and medicine, refers to any type of force that is applied to body tissues or organs, which can cause deformation or displacement of those structures. Mechanical stress can be either external, such as forces exerted on the body during physical activity or trauma, or internal, such as the pressure changes that occur within blood vessels or other hollow organs.

Mechanical stress can have a variety of effects on the body, depending on the type, duration, and magnitude of the force applied. For example, prolonged exposure to mechanical stress can lead to tissue damage, inflammation, and chronic pain. Additionally, abnormal or excessive mechanical stress can contribute to the development of various musculoskeletal disorders, such as tendinitis, osteoarthritis, and herniated discs.

In order to mitigate the negative effects of mechanical stress, the body has a number of adaptive responses that help to distribute forces more evenly across tissues and maintain structural integrity. These responses include changes in muscle tone, joint positioning, and connective tissue stiffness, as well as the remodeling of bone and other tissues over time. However, when these adaptive mechanisms are overwhelmed or impaired, mechanical stress can become a significant factor in the development of various pathological conditions.

In medical terms, the heart is a muscular organ located in the thoracic cavity that functions as a pump to circulate blood throughout the body. It's responsible for delivering oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. The human heart is divided into four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it out to the rest of the body. The heart's rhythmic contractions and relaxations are regulated by a complex electrical conduction system.

Protein kinases are a group of enzymes that play a crucial role in many cellular processes by adding phosphate groups to other proteins, a process known as phosphorylation. This modification can activate or deactivate the target protein's function, thereby regulating various signaling pathways within the cell. Protein kinases are essential for numerous biological functions, including metabolism, signal transduction, cell cycle progression, and apoptosis (programmed cell death). Abnormal regulation of protein kinases has been implicated in several diseases, such as cancer, diabetes, and neurological disorders.

"Anura" is a term used in the field of zoology, particularly in the study of amphibians. It refers to a order that includes frogs and toads. The name "Anura" comes from the Greek language, with "an-" meaning "without," and "oura" meaning "tail." This is a reference to the fact that members of this order lack tails in their adult form.

The Anura order is characterized by several distinct features:

1. They have short, powerful legs that are well adapted for jumping or leaping.
2. Their forelimbs are smaller and less specialized than their hind limbs.
3. Most anurans have a moist, glandular skin, which helps them to breathe and absorb water.
4. Anura includes both aquatic and terrestrial species, with varying degrees of adaptations for each environment.
5. They lay their eggs in water, and their larvae (tadpoles) are aquatic, undergoing a process called metamorphosis to transform into the adult form.

Anura contains approximately 7,000 known species, making it one of the largest orders of vertebrates. They have a cosmopolitan distribution and can be found on every continent except Antarctica. Anurans play essential roles in many ecosystems as both predators and prey, contributing to the regulation of insect populations and serving as indicators of environmental health.

Micromanipulation is a term used in the field of medicine, specifically in assisted reproductive technologies (ARTs) such as in vitro fertilization (IVF). It refers to a technique that involves the manipulation of oocytes (human eggs), sperm, and/or embryos under a microscope using micromanipulative tools and equipment.

The most common form of micromanipulation is intracytoplasmic sperm injection (ICSI), where a single sperm is selected and injected directly into the cytoplasm of an oocyte to facilitate fertilization. Other forms of micromanipulation include assisted hatching (AH), where a small opening is made in the zona pellucida (the protective layer surrounding the embryo) to help the embryo hatch and implant into the uterus, and embryo biopsy, which involves removing one or more cells from an embryo for genetic testing.

Micromanipulation requires specialized training and equipment and is typically performed in IVF laboratories by experienced embryologists. The goal of micromanipulation is to improve the chances of successful fertilization, implantation, and pregnancy, particularly in cases where conventional methods have been unsuccessful or when there are specific fertility issues, such as male factor infertility or genetic disorders.

Muscular diseases, also known as myopathies, refer to a group of conditions that affect the functionality and health of muscle tissue. These diseases can be inherited or acquired and may result from inflammation, infection, injury, or degenerative processes. They can cause symptoms such as weakness, stiffness, cramping, spasms, wasting, and loss of muscle function.

Examples of muscular diseases include:

1. Duchenne Muscular Dystrophy (DMD): A genetic disorder that results in progressive muscle weakness and degeneration due to a lack of dystrophin protein.
2. Myasthenia Gravis: An autoimmune disease that causes muscle weakness and fatigue, typically affecting the eyes and face, throat, and limbs.
3. Inclusion Body Myositis (IBM): A progressive muscle disorder characterized by muscle inflammation and wasting, typically affecting older adults.
4. Polymyositis: An inflammatory myopathy that causes muscle weakness and inflammation throughout the body.
5. Metabolic Myopathies: A group of inherited disorders that affect muscle metabolism, leading to exercise intolerance, muscle weakness, and other symptoms.
6. Muscular Dystonias: Involuntary muscle contractions and spasms that can cause abnormal postures or movements.

It is important to note that muscular diseases can have a significant impact on an individual's quality of life, mobility, and overall health. Proper diagnosis and treatment are crucial for managing symptoms and improving outcomes.

Calcium is an essential mineral that is vital for various physiological processes in the human body. The medical definition of calcium is as follows:

Calcium (Ca2+) is a crucial cation and the most abundant mineral in the human body, with approximately 99% of it found in bones and teeth. It plays a vital role in maintaining structural integrity, nerve impulse transmission, muscle contraction, hormonal secretion, blood coagulation, and enzyme activation.

Calcium homeostasis is tightly regulated through the interplay of several hormones, including parathyroid hormone (PTH), calcitonin, and vitamin D. Dietary calcium intake, absorption, and excretion are also critical factors in maintaining optimal calcium levels in the body.

Hypocalcemia refers to low serum calcium levels, while hypercalcemia indicates high serum calcium levels. Both conditions can have detrimental effects on various organ systems and require medical intervention to correct.

Myosin Heavy Chains are the large, essential components of myosin molecules, which are responsible for the molecular motility in muscle cells. These heavy chains have a molecular weight of approximately 200 kDa and form the motor domain of myosin, which binds to actin filaments and hydrolyzes ATP to generate force and movement during muscle contraction. There are several different types of myosin heavy chains, each with specific roles in various tissues and cellular functions. In skeletal and cardiac muscles, for example, myosin heavy chains have distinct isoforms that contribute to the contractile properties of these tissues.

"Animal Flight" is not a medical term per se, but it is a concept that is studied in the field of comparative physiology and biomechanics, which are disciplines related to medicine. Animal flight refers to the ability of certain animal species to move through the air by flapping their wings or other appendages. This mode of locomotion is most commonly associated with birds, bats, and insects, but some mammals such as flying squirrels and sugar gliders are also capable of gliding through the air.

The study of animal flight involves understanding the biomechanics of how animals generate lift and propulsion, as well as the physiological adaptations that allow them to sustain flight. For example, birds have lightweight skeletons and powerful chest muscles that enable them to flap their wings rapidly and generate lift. Bats, on the other hand, use a more complex system of membranes and joints to manipulate their wings and achieve maneuverability in flight.

Understanding animal flight has important implications for the design of aircraft and other engineering systems, as well as for our broader understanding of how animals have evolved to adapt to their environments.

LIM domain proteins are a group of transcription factors that contain LIM domains, which are cysteine-rich zinc-binding motifs. These proteins play crucial roles in various cellular processes such as gene regulation, cell proliferation, differentiation, and migration. They are involved in the development and functioning of several organ systems including the nervous system, cardiovascular system, and musculoskeletal system. LIM domain proteins can interact with other proteins and DNA to regulate gene expression and have been implicated in various diseases such as cancer and neurological disorders.

Immobilization is a medical term that refers to the restriction of normal mobility or motion of a body part, usually to promote healing and prevent further injury. This is often achieved through the use of devices such as casts, splints, braces, slings, or traction. The goal of immobilization is to keep the injured area in a fixed position so that it can heal properly without additional damage. It may be used for various medical conditions, including fractures, dislocations, sprains, strains, and soft tissue injuries. Immobilization helps reduce pain, minimize swelling, and protect the injured site from movement that could worsen the injury or impair healing.

Immunoelectron microscopy (IEM) is a specialized type of electron microscopy that combines the principles of immunochemistry and electron microscopy to detect and localize specific antigens within cells or tissues at the ultrastructural level. This technique allows for the visualization and identification of specific proteins, viruses, or other antigenic structures with a high degree of resolution and specificity.

In IEM, samples are first fixed, embedded, and sectioned to prepare them for electron microscopy. The sections are then treated with specific antibodies that have been labeled with electron-dense markers, such as gold particles or ferritin. These labeled antibodies bind to the target antigens in the sample, allowing for their visualization under an electron microscope.

There are several different methods of IEM, including pre-embedding and post-embedding techniques. Pre-embedding involves labeling the antigens before embedding the sample in resin, while post-embedding involves labeling the antigens after embedding. Post-embedding techniques are generally more commonly used because they allow for better preservation of ultrastructure and higher resolution.

IEM is a valuable tool in many areas of research, including virology, bacteriology, immunology, and cell biology. It can be used to study the structure and function of viruses, bacteria, and other microorganisms, as well as the distribution and localization of specific proteins and antigens within cells and tissues.

Muscle cells, also known as muscle fibers, are specialized cells that have the ability to contract and generate force, allowing for movement of the body and various internal organ functions. There are three main types of muscle tissue: skeletal, cardiac, and smooth.

Skeletal muscle cells are voluntary striated muscles attached to bones, enabling body movements and posture. They are multinucleated, with numerous nuclei located at the periphery of the cell. These cells are often called muscle fibers and can be quite large, extending the entire length of the muscle.

Cardiac muscle cells form the contractile tissue of the heart. They are also striated but have a single nucleus per cell and are interconnected by specialized junctions called intercalated discs, which help coordinate contraction throughout the heart.

Smooth muscle cells are found in various internal organs such as the digestive, respiratory, and urinary tracts, blood vessels, and the reproductive system. They are involuntary, non-striated muscles that control the internal organ functions. Smooth muscle cells have a single nucleus per cell and can either be spindle-shaped or stellate (star-shaped).

In summary, muscle cells are specialized contractile cells responsible for movement and various internal organ functions in the human body. They can be categorized into three types: skeletal, cardiac, and smooth, based on their structure, location, and function.

"Cells, cultured" is a medical term that refers to cells that have been removed from an organism and grown in controlled laboratory conditions outside of the body. This process is called cell culture and it allows scientists to study cells in a more controlled and accessible environment than they would have inside the body. Cultured cells can be derived from a variety of sources, including tissues, organs, or fluids from humans, animals, or cell lines that have been previously established in the laboratory.

Cell culture involves several steps, including isolation of the cells from the tissue, purification and characterization of the cells, and maintenance of the cells in appropriate growth conditions. The cells are typically grown in specialized media that contain nutrients, growth factors, and other components necessary for their survival and proliferation. Cultured cells can be used for a variety of purposes, including basic research, drug development and testing, and production of biological products such as vaccines and gene therapies.

It is important to note that cultured cells may behave differently than they do in the body, and results obtained from cell culture studies may not always translate directly to human physiology or disease. Therefore, it is essential to validate findings from cell culture experiments using additional models and ultimately in clinical trials involving human subjects.

In the context of medicine, "needles" are thin, sharp, and typically hollow instruments used in various medical procedures to introduce or remove fluids from the body, administer medications, or perform diagnostic tests. They consist of a small-gauge metal tube with a sharp point on one end and a hub on the other, where a syringe is attached.

There are different types of needles, including:

1. Hypodermic needles: These are used for injections, such as intramuscular (IM), subcutaneous (SC), or intravenous (IV) injections, to deliver medications directly into the body. They come in various sizes and lengths depending on the type of injection and the patient's age and weight.
2. Blood collection needles: These are used for drawing blood samples for diagnostic tests. They have a special vacuum-assisted design that allows them to easily penetrate veins and collect the required amount of blood.
3. Surgical needles: These are used in surgeries for suturing (stitching) wounds or tissues together. They are typically curved and made from stainless steel, with a triangular or reverse cutting point to facilitate easy penetration through tissues.
4. Acupuncture needles: These are thin, solid needles used in traditional Chinese medicine for acupuncture therapy. They are inserted into specific points on the body to stimulate energy flow and promote healing.

It is essential to follow proper infection control procedures when handling and disposing of needles to prevent the spread of bloodborne pathogens and infectious diseases.

Microscopy is a technical field in medicine that involves the use of microscopes to observe structures and phenomena that are too small to be seen by the naked eye. It allows for the examination of samples such as tissues, cells, and microorganisms at high magnifications, enabling the detection and analysis of various medical conditions, including infections, diseases, and cellular abnormalities.

There are several types of microscopy used in medicine, including:

1. Light Microscopy: This is the most common type of microscopy, which uses visible light to illuminate and magnify samples. It can be used to examine a wide range of biological specimens, such as tissue sections, blood smears, and bacteria.
2. Electron Microscopy: This type of microscopy uses a beam of electrons instead of light to produce highly detailed images of samples. It is often used in research settings to study the ultrastructure of cells and tissues.
3. Fluorescence Microscopy: This technique involves labeling specific molecules within a sample with fluorescent dyes, allowing for their visualization under a microscope. It can be used to study protein interactions, gene expression, and cell signaling pathways.
4. Confocal Microscopy: This type of microscopy uses a laser beam to scan a sample point by point, producing high-resolution images with reduced background noise. It is often used in medical research to study the structure and function of cells and tissues.
5. Scanning Probe Microscopy: This technique involves scanning a sample with a physical probe, allowing for the measurement of topography, mechanical properties, and other characteristics at the nanoscale. It can be used in medical research to study the structure and function of individual molecules and cells.

Stress fibers are specialized cytoskeletal structures composed primarily of actin filaments, along with myosin II and other associated proteins. They are called "stress" fibers because they are thought to provide cells with the ability to resist and respond to mechanical stresses. These structures play a crucial role in maintaining cell shape, facilitating cell migration, and mediating cell-cell and cell-matrix adhesions. Stress fibers form bundles that span the length of the cell and connect to focal adhesion complexes at their ends, allowing for the transmission of forces between the extracellular matrix and the cytoskeleton. They are dynamic structures that can undergo rapid assembly and disassembly in response to various stimuli, including changes in mechanical stress, growth factor signaling, and cellular differentiation.

Biological models, also known as physiological models or organismal models, are simplified representations of biological systems, processes, or mechanisms that are used to understand and explain the underlying principles and relationships. These models can be theoretical (conceptual or mathematical) or physical (such as anatomical models, cell cultures, or animal models). They are widely used in biomedical research to study various phenomena, including disease pathophysiology, drug action, and therapeutic interventions.

Examples of biological models include:

1. Mathematical models: These use mathematical equations and formulas to describe complex biological systems or processes, such as population dynamics, metabolic pathways, or gene regulation networks. They can help predict the behavior of these systems under different conditions and test hypotheses about their underlying mechanisms.
2. Cell cultures: These are collections of cells grown in a controlled environment, typically in a laboratory dish or flask. They can be used to study cellular processes, such as signal transduction, gene expression, or metabolism, and to test the effects of drugs or other treatments on these processes.
3. Animal models: These are living organisms, usually vertebrates like mice, rats, or non-human primates, that are used to study various aspects of human biology and disease. They can provide valuable insights into the pathophysiology of diseases, the mechanisms of drug action, and the safety and efficacy of new therapies.
4. Anatomical models: These are physical representations of biological structures or systems, such as plastic models of organs or tissues, that can be used for educational purposes or to plan surgical procedures. They can also serve as a basis for developing more sophisticated models, such as computer simulations or 3D-printed replicas.

Overall, biological models play a crucial role in advancing our understanding of biology and medicine, helping to identify new targets for therapeutic intervention, develop novel drugs and treatments, and improve human health.

Muscle spindles are specialized sensory organs found within the muscle belly, which primarily function as proprioceptors, providing information about the length and rate of change in muscle length. They consist of small, encapsulated bundles of intrafusal muscle fibers that are interspersed among the extrafusal muscle fibers (the ones responsible for force generation).

Muscle spindles have two types of sensory receptors called primary and secondary endings. Primary endings are located near the equatorial region of the intrafusal fiber, while secondary endings are situated more distally. These endings detect changes in muscle length and transmit this information to the central nervous system (CNS) through afferent nerve fibers.

The activation of muscle spindles plays a crucial role in reflexive responses, such as the stretch reflex (myotatic reflex), which helps maintain muscle tone and joint stability. Additionally, they contribute to our sense of body position and movement awareness, known as kinesthesia.

Phase-contrast microscopy is a type of optical microscopy that allows visualization of transparent or translucent specimens, such as living cells and their organelles, by increasing the contrast between areas with different refractive indices within the sample. This technique works by converting phase shifts in light passing through the sample into changes in amplitude, which can then be observed as differences in brightness and contrast.

In a phase-contrast microscope, a special condenser and objective are used to create an optical path difference between the direct and diffracted light rays coming from the specimen. The condenser introduces a phase shift for the diffracted light, while the objective contains a phase ring that compensates for this shift in the direct light. This results in the direct light appearing brighter than the diffracted light, creating contrast between areas with different refractive indices within the sample.

Phase-contrast microscopy is particularly useful for observing unstained living cells and their dynamic processes, such as cell division, motility, and secretion, without the need for stains or dyes that might affect their viability or behavior.

Sarcolemma is the medical term for the cell membrane that surrounds a muscle fiber or a skeletal muscle cell. It is responsible for providing protection and structure to the muscle fiber, as well as regulating the movement of ions and other molecules in and out of the cell. The sarcolemma plays a crucial role in the excitation-contraction coupling process that allows muscles to contract and relax.

The sarcolemma is composed of two main layers: the outer plasma membrane, which is similar to the cell membranes of other cells, and the inner basal lamina, which provides structural support and helps to anchor the muscle fiber to surrounding tissues. The sarcolemma also contains various ion channels, receptors, and transporters that are involved in regulating muscle function and communication with other cells.

Damage to the sarcolemma can lead to a variety of muscle disorders, including muscular dystrophy and myasthenia gravis.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Biophysical phenomena refer to the observable events and processes that occur in living organisms, which can be explained and studied using the principles and methods of physics. These phenomena can include a wide range of biological processes at various levels of organization, from molecular interactions to whole-organism behaviors. Examples of biophysical phenomena include the mechanics of muscle contraction, the electrical activity of neurons, the transport of molecules across cell membranes, and the optical properties of biological tissues. By applying physical theories and techniques to the study of living systems, biophysicists seek to better understand the fundamental principles that govern life and to develop new approaches for diagnosing and treating diseases.

Microfilament proteins are a type of structural protein that form part of the cytoskeleton in eukaryotic cells. They are made up of actin monomers, which polymerize to form long, thin filaments. These filaments are involved in various cellular processes such as muscle contraction, cell division, and cell motility. Microfilament proteins also interact with other cytoskeletal components like intermediate filaments and microtubules to maintain the overall shape and integrity of the cell. Additionally, they play a crucial role in the formation of cell-cell junctions and cell-matrix adhesions, which are essential for tissue structure and function.

Fluorescence microscopy is a type of microscopy that uses fluorescent dyes or proteins to highlight and visualize specific components within a sample. In this technique, the sample is illuminated with high-energy light, typically ultraviolet (UV) or blue light, which excites the fluorescent molecules causing them to emit lower-energy, longer-wavelength light, usually visible light in the form of various colors. This emitted light is then collected by the microscope and detected to produce an image.

Fluorescence microscopy has several advantages over traditional brightfield microscopy, including the ability to visualize specific structures or molecules within a complex sample, increased sensitivity, and the potential for quantitative analysis. It is widely used in various fields of biology and medicine, such as cell biology, neuroscience, and pathology, to study the structure, function, and interactions of cells and proteins.

There are several types of fluorescence microscopy techniques, including widefield fluorescence microscopy, confocal microscopy, two-photon microscopy, and total internal reflection fluorescence (TIRF) microscopy, each with its own strengths and limitations. These techniques can provide valuable insights into the behavior of cells and proteins in health and disease.

A laser is not a medical term per se, but a physical concept that has important applications in medicine. The term "LASER" stands for "Light Amplification by Stimulated Emission of Radiation." It refers to a device that produces and amplifies light with specific characteristics, such as monochromaticity (single wavelength), coherence (all waves moving in the same direction), and high intensity.

In medicine, lasers are used for various therapeutic and diagnostic purposes, including surgery, dermatology, ophthalmology, and dentistry. They can be used to cut, coagulate, or vaporize tissues with great precision, minimizing damage to surrounding structures. Additionally, lasers can be used to detect and measure physiological parameters, such as blood flow and oxygen saturation.

It's important to note that while lasers are powerful tools in medicine, they must be used by trained professionals to ensure safe and effective treatment.

The Fluorescent Antibody Technique (FAT) is a type of immunofluorescence assay used in laboratory medicine and pathology for the detection and localization of specific antigens or antibodies in tissues, cells, or microorganisms. In this technique, a fluorescein-labeled antibody is used to selectively bind to the target antigen or antibody, forming an immune complex. When excited by light of a specific wavelength, the fluorescein label emits light at a longer wavelength, typically visualized as green fluorescence under a fluorescence microscope.

The FAT is widely used in diagnostic microbiology for the identification and characterization of various bacteria, viruses, fungi, and parasites. It has also been applied in the diagnosis of autoimmune diseases and certain cancers by detecting specific antibodies or antigens in patient samples. The main advantage of FAT is its high sensitivity and specificity, allowing for accurate detection and differentiation of various pathogens and disease markers. However, it requires specialized equipment and trained personnel to perform and interpret the results.

Biophysics is a interdisciplinary field that combines the principles and methods of physics with those of biology to study biological systems and phenomena. It involves the use of physical theories, models, and techniques to understand and explain the properties, functions, and behaviors of living organisms and their constituents, such as cells, proteins, and DNA.

Biophysics can be applied to various areas of biology, including molecular biology, cell biology, neuroscience, and physiology. It can help elucidate the mechanisms of biological processes at the molecular and cellular levels, such as protein folding, ion transport, enzyme kinetics, gene expression, and signal transduction. Biophysical methods can also be used to develop diagnostic and therapeutic tools for medical applications, such as medical imaging, drug delivery, and gene therapy.

Examples of biophysical techniques include X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, electron microscopy, fluorescence microscopy, atomic force microscopy, and computational modeling. These methods allow researchers to probe the structure, dynamics, and interactions of biological molecules and systems with high precision and resolution, providing insights into their functions and behaviors.

Muscle relaxation, in a medical context, refers to the process of reducing tension and promoting relaxation in the skeletal muscles. This can be achieved through various techniques, including progressive muscle relaxation (PMR), where individuals consciously tense and then release specific muscle groups in a systematic manner.

PMR has been shown to help reduce anxiety, stress, and muscle tightness, and improve overall well-being. It is often used as a complementary therapy in conjunction with other treatments for conditions such as chronic pain, headaches, and insomnia.

Additionally, muscle relaxation can also be facilitated through pharmacological interventions, such as the use of muscle relaxant medications. These drugs work by inhibiting the transmission of signals between nerves and muscles, leading to a reduction in muscle tone and spasticity. They are commonly used to treat conditions such as multiple sclerosis, cerebral palsy, and spinal cord injuries.

Protein isoforms are different forms or variants of a protein that are produced from a single gene through the process of alternative splicing, where different exons (or parts of exons) are included in the mature mRNA molecule. This results in the production of multiple, slightly different proteins that share a common core structure but have distinct sequences and functions. Protein isoforms can also arise from genetic variations such as single nucleotide polymorphisms or mutations that alter the protein-coding sequence of a gene. These differences in protein sequence can affect the stability, localization, activity, or interaction partners of the protein isoform, leading to functional diversity and specialization within cells and organisms.

"Newborn animals" refers to the very young offspring of animals that have recently been born. In medical terminology, newborns are often referred to as "neonates," and they are classified as such from birth until about 28 days of age. During this time period, newborn animals are particularly vulnerable and require close monitoring and care to ensure their survival and healthy development.

The specific needs of newborn animals can vary widely depending on the species, but generally, they require warmth, nutrition, hydration, and protection from harm. In many cases, newborns are unable to regulate their own body temperature or feed themselves, so they rely heavily on their mothers for care and support.

In medical settings, newborn animals may be examined and treated by veterinarians to ensure that they are healthy and receiving the care they need. This can include providing medical interventions such as feeding tubes, antibiotics, or other treatments as needed to address any health issues that arise. Overall, the care and support of newborn animals is an important aspect of animal medicine and conservation efforts.

The sarcoplasmic reticulum (SR) is a specialized type of smooth endoplasmic reticulum found in muscle cells, particularly in striated muscles such as skeletal and cardiac muscles. It is a complex network of tubules that surrounds the myofibrils, the contractile elements of the muscle fiber.

The primary function of the sarcoplasmic reticulum is to store calcium ions (Ca2+) and regulate their release during muscle contraction and uptake during muscle relaxation. The SR contains a high concentration of calcium-binding proteins, such as calsequestrin, which help to maintain this storage.

The release of calcium ions from the sarcoplasmic reticulum is triggered by an action potential that travels along the muscle fiber's sarcolemma and into the muscle fiber's interior (the sarcoplasm). This action potential causes the voltage-gated calcium channels in the SR membrane, known as ryanodine receptors, to open, releasing Ca2+ ions into the sarcoplasm.

The increased concentration of Ca2+ ions in the sarcoplasm triggers muscle contraction by binding to troponin, a protein associated with actin filaments, causing a conformational change that exposes the active sites on actin for myosin heads to bind and generate force.

After muscle contraction, the calcium ions must be actively transported back into the sarcoplasmic reticulum by Ca2+ ATPase pumps, also known as sarco(endo)plasmic reticulum calcium ATPases (SERCAs). This process helps to lower the concentration of Ca2+ in the sarcoplasm and allows the muscle fiber to relax.

Overall, the sarcoplasmic reticulum plays a crucial role in excitation-contraction coupling, the process by which action potentials trigger muscle contraction.

The cytoskeleton is a complex network of various protein filaments that provides structural support, shape, and stability to the cell. It plays a crucial role in maintaining cellular integrity, intracellular organization, and enabling cell movement. The cytoskeleton is composed of three major types of protein fibers: microfilaments (actin filaments), intermediate filaments, and microtubules. These filaments work together to provide mechanical support, participate in cell division, intracellular transport, and help maintain the cell's architecture. The dynamic nature of the cytoskeleton allows cells to adapt to changing environmental conditions and respond to various stimuli.

A chick embryo refers to the developing organism that arises from a fertilized chicken egg. It is often used as a model system in biological research, particularly during the stages of development when many of its organs and systems are forming and can be easily observed and manipulated. The study of chick embryos has contributed significantly to our understanding of various aspects of developmental biology, including gastrulation, neurulation, organogenesis, and pattern formation. Researchers may use various techniques to observe and manipulate the chick embryo, such as surgical alterations, cell labeling, and exposure to drugs or other agents.

"Chickens" is a common term used to refer to the domesticated bird, Gallus gallus domesticus, which is widely raised for its eggs and meat. However, in medical terms, "chickens" is not a standard term with a specific definition. If you have any specific medical concern or question related to chickens, such as food safety or allergies, please provide more details so I can give a more accurate answer.

Actin molecules are bound to the Z-line, which forms the borders of the sarcomere. Other bands appear when the sarcomere is ... The myofibrils of smooth muscle cells are not arranged into sarcomeres. The sarcomeres give skeletal and cardiac muscle their ... Length of the actin and myosin filaments (taken together as sarcomere length) affects force and velocity - longer sarcomeres ... Wikimedia Commons has media related to Sarcomeres. MBInfo: Sarcomere MBInfo: Contractile Fiber Muscular Tissues Videos ...
Kreis, Thomas E.; Birchmeier, Walter (November 1980). "Stress fiber sarcomeres of fibroblasts are contractile". Cell. 22 (2): ... fibers in the ventral regions of non-motile cells show a periodic polarity that is similar to the organization of the sarcomere ...
Scott AB (1994). "Change of eye muscle sarcomeres according to eye position". Journal of Pediatric Ophthalmology and Strabismus ... so that a paralyzed muscle tends to get stretched-out by its antagonist and grows longer by addition of serial sarcomeres (the ... contractile units of skeletal muscles), while the antagonist tends to grow shorter by deletion of sarcomeres,[unreliable ...
... appears to be necessary for the proper incorporation of myosin filaments into sarcomeres and in the assembly of A- ... Titin, obscurin, obscurin-like-1 and myomesin form a ternary complex at sarcomeric M-bands that is critical for sarcomere ... Obscurin is expressed in cardiac and skeletal muscle, and plays a role in the organization of myofibrils during sarcomere ... Borisov AB, Martynova MG, Russell MW (Apr 2008). "Early incorporation of obscurin into nascent sarcomeres: implication for ...
Scott, A. B. (March 6, 1994). "Change of eye muscle sarcomeres according to eye position". Journal of Pediatric Ophthalmology ...
leading to breakdown of the sarcomere. This was found to be due to regulation of gene expression of Trim63/MuRF1 by the FOXO ( ... where titin's N-terminal and C-terminal regions respectively bind to the sarcomere. In vitro binding studies have shown that ... which is a major component of the sarcomere, is an important mechanism in the breakdown of skeletal muscle under atrophy ...
They run through the core of each thick filament and anchor it to the Z-line, the end point of a sarcomere.[citation needed] ... The muscle fiber relaxes and the entire sarcomere lengthens. The muscle fiber is now prepared for the next contraction. The ... Muscle contraction consists of the simultaneous shortening of multiple sarcomeres. The axon terminal of a motor neuron releases ... Thus muscle contraction occurs, and the sarcomere shortens as this process takes place. The enzyme acetylcholinesterase breaks ...
These sarcomeres are arranged in adjacent formations along the myofibrils. Similarly to the plasma membrane of other cells, the ... The z-line defines the borders of each sarcomere and act as the connection point between the thin filaments. The t-tubules and ... A myocyte is composed of multiple myofibrils, which contain the "contractile units" of the muscle known as a sarcomere. ... These structures attached to the sarcomere z-lines help to promote interaction between the extracellular space and the interior ...
In addition to sarcomere activity, it has been shown that myomesin also plays a role in the assembly of the sarcomere. In order ... Myomesin plays an important role in the structure of sarcomeres. They are found in the M-band region of the sarcomere, between ... This is extremely important as if even one piece of the M-line is missing, the A-band of the sarcomere will collapse and the ... Since the Z-disc region of the sarcomere is very stiff and unable to bend for contraction, the elastic activity of myomesin in ...
The costamere is a structural-functional component of striated muscle cells which connects the sarcomere of the muscle to the ... They physically couple force-generating sarcomeres with the sarcolemma in striated muscle cells and are thus considered one of ... They are also responsible for the lateral transmission of the sarcomere-generated contractile force to the sarcolemma and the ... Restated, filamin C physically links the two complexes that constitute the costamere to sarcomeres by interacting with the ...
In addition to sarcomeres, PKCε also targets cardiac mitochondria. Proteomic analysis of PKCε signaling complexes in mice ... PKCε translocates to cardiac muscle sarcomeres and modulates contractility of the myocardium. PKCε binds RACK2 at Z-lines with ... A role for focal adhesion kinase at costameres in strain-sensing and modulation of sarcomere length has been linked to ... PKCε translocation to sarcomeres and phosphorylation of cTnI and cMyBPC is involved in the κ-opioid- and α-adrenergic-dependent ...
At the sarcomere, ARPP binds titin at I-bands, which is potentiated by homo-dimerization and can alter the protein kinase A/ ... ARPP localizes to both nuclei and sarcomeres in muscle cells. ARPP may play a role in the differentiation of myocytes, as ARPP ... with longer resting sarcomere length, decreased fiber stiffness, expression of a longer titin isoform, greater degree of torque ... a link between the sarcomere and the nucleus in skeletal muscle". J. Mol. Biol. 339 (2): 313-25. doi:10.1016/j.jmb.2004.03.071 ...
HCM is described as a disease of the sarcomere, because mutations in the contractile proteins of the sarcomere have been ... The calcium sensitivity of the sarcomere, that is, the calcium concentration at which muscle contraction occurs, is directly ... Hwang PM, Sykes BD (Apr 2015). "Targeting the sarcomere to correct muscle function". Nature Reviews. Drug Discovery. 14 (5): ...
"Sliding Filament Theory, Sarcomere, Muscle Contraction, Myosin , Learn Science at Scitable". www.nature.com. Retrieved 2018-09- ...
... found in the sarcomere MYL5 (chromosome 4p16.3); found in the sarcomere MYL7 (chromosome 12q13.2); found in the sarcomere MYL9 ...
Chapin, LM; Blankman, E; Smith, MA; Shiu, YT; Beckerle, MC (2012). "Lateral communication between stress fiber sarcomeres ...
Nicol RL, Frey N, Pearson G, Cobb M, Richardson J, Olson EN (Jun 2001). "Activated MEK5 induces serial assembly of sarcomeres ...
They occur at the Z line of the sarcomere and can be visualized easily when observing a longitudinal section of the tissue. ... Fascia adherens are anchoring sites for actin, and connect to the closest sarcomere. Desmosomes prevent separation during ... Hyperdistended myocardiocytes with detached sarcomeres, and in proximity of hypercontracted myocardiocytes. Square-shaped ...
Niimura H, Patton KK, McKenna WJ, Soults J, Maron BJ, Seidman JG, Seidman CE (Jan 2002). "Sarcomere protein gene mutations in ... Niimura H, Patton KK, McKenna WJ, Soults J, Maron BJ, Seidman JG, Seidman CE (Jan 2002). "Sarcomere protein gene mutations in ... This enables proper assembly of myofibrils and thus, more organized sarcomeres. All of the mice in the study developed HCM ... This process converts chemical to mechanical energy, and propels shortening of the sarcomeres in order to generate ...
DOI:10.1016/S0006-3495(93)81482-6 Wang, K.; Wright, J. (1988). "Architecture of the sarcomere matrix of skeletal muscle: ... "Viscoelasticity of the sarcomere matrix of skeletal muscles. The titin-myosin composite filament is a dual-stage molecular ... which fundamentally changed our understanding of muscle sarcomeres. At UT Wang was promoted to associate professor in 1984 and ... extended and ramified their findings on the structures of Titin and Nebulin and how they function within the sarcomere. In 1997 ...
"G9a inhibits MEF2C activity to control sarcomere assembly". Scientific Reports. 6 (1): 34163. Bibcode:2016NatSR...634163O. doi: ...
Gupta MP, Samant SA, Smith SH, Shroff SG (April 2008). "HDAC4 and PCAF bind to cardiac sarcomeres and play a role in regulating ... Luther PK (2009). "The vertebrate muscle Z-disc: sarcomere anchor for structure and signalling". Journal of Muscle Research and ... "Beyond the sarcomere: CSRP3 mutations cause hypertrophic cardiomyopathy". Human Molecular Genetics. 17 (18): 2753-65. doi: ... different Z-line components and acts as a scaffold protein promoting the assembly of macromolecular complexes along sarcomeres ...
The sarcomere is attached to other organelles such as the mitochondria by intermediate filaments in the cytoskeleton. The ... At the muscle-tendon interface, force is transmitted from the sarcomeres in the muscle cells to the tendon. Muscles and tendons ... In addition to the actin and myosin myofilaments in the myofibrils that make up the contractile sarcomeres, there are two other ... The muscle tissue of a skeletal muscle is striated - having a striped appearance due to the arrangement of the sarcomeres. ...
The sarcomeres become misaligned and result in the disorganization of muscle fibers. This mutation also results in muscle cell ...
Each sarcomere is delimited by two very dark colored bands called Z-discs or Z-lines (from the German zwischen meaning between ... The names of the various sub-regions of the sarcomere are based on their relatively lighter or darker appearance when viewed ... When a muscle contracts, the actin is pulled along myosin toward the center of the sarcomere until the actin and myosin ... These subunits are called sarcomeres that are around three μm in length. The muscle cell is nearly filled with myofibrils ...
Sarcomeres are added in parallel, as for example occurs in hypertrophic cardiomyopathy.[citation needed] In the heart, ...
The pacemaker cells are only weakly contractile without sarcomeres, and are connected to neighboring contractile cells via gap ... The regular organization of myofibrils into sarcomeres gives cardiac muscle cells a striped or striated appearance when looked ... Cardiomyocyte hypertrophy occurs through sarcomerogenesis, the creation of new sarcomere units in the cell. During heart volume ... These are organized into sarcomeres, the fundamental contractile units of muscle cells. ...
This causes the filaments to start sliding and the sarcomeres to become shorter. This requires a large amount of ATP, as it is ... The smallest contractile unit in the fiber is called the sarcomere which is a repeating unit within two Z bands. The sarcoplasm ... Actin filaments are anchored by dense bodies (similar to the Z discs in sarcomeres) to the sarcolemma. A myoblast is an ... The contraction of all the sarcomeres results in the contraction of the whole muscle fiber. This contraction of the myocyte is ...
Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle ... at Z-lines towards the center of the sarcomere. Polymerization of globular actin (G-actin) leads to a structural filament (F- ... "Mutations in sarcomere protein genes in left ventricular noncompaction". Circulation. 117 (22): 2893-901. doi:10.1161/ ...
The power stroke moves the actin filament inwards, thereby shortening the sarcomere. Myosin then releases ADP but still remains ... This fine myofilament maintains uniform tension across the sarcomere by pulling the thick filament into a central position. ... Gordon AM, Huxley AF, Julian FJ (1966). "The variation in isometric tension with sarcomere length in vertebrate muscle fibres ... Physiologically, this contraction is not uniform across the sarcomere; the central position of the thick filaments becomes ...
Actin molecules are bound to the Z-line, which forms the borders of the sarcomere. Other bands appear when the sarcomere is ... The myofibrils of smooth muscle cells are not arranged into sarcomeres. The sarcomeres give skeletal and cardiac muscle their ... Length of the actin and myosin filaments (taken together as sarcomere length) affects force and velocity - longer sarcomeres ... Wikimedia Commons has media related to Sarcomeres. MBInfo: Sarcomere MBInfo: Contractile Fiber Muscular Tissues Videos ...
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The functional sarcomere is controlled by calcium levels which vary due to calcium influx caused by electrical signals acting ... HDAC4 and PCAF bind to cardiac sarcomeres and play a role in regulating myofilament contractile activity. J. Biol. Chem. 283, ... Guptas laboratory went on to show that an additional HDAC (HDAC3) is associated with cardiac sarcomeres9. Using a broad ... A cardiac myosin light chain kinase regulates sarcomere assembly in the vertebrate heart. J. Clin. Invest. 117, 2812-24. ...
... muscles quantifies the transcriptional dynamics during muscle morphogenesis and identifies three ordered phases of sarcomere ... Note the sarcomere assembly at 34 hr, followed by sarcomere addition until ~48 hr and sarcomere maturation after ~48 hr APF. (E ... These immature sarcomeres contract spontaneously. Phase 3 - Sarcomere maturation: After 48 hr APF, sarcomere protein expression ... Each of the 2000 myofibrils contains about 80 immature sarcomeres. Phase 2 - Sarcomere addition: Sarcomere protein expression ...
Role of Muscle stem cells in sarcomere addition and contracture development. *Dayanidhi, Sudarshan (PD/PI) ... mouse model that can undergo conditional knockdown to evaluate if adequate muscle stem cell number is required for sarcomere ...
The importance of serial sarcomere addition for muscle function and the impact of aging Journal Articles ... potentially reflective of a decrease in serial sarcomere number (SSN). Interventions that promote the growth of new serial ... sarcomeres, such as chronic stretching and eccentric-biased resistance training, have been suggested as potential ways to ...
The "expanding-sarcomere, sliding-filament" model of sarcomere shortening is discussed in terms of the current concepts of ... THE RELATIONSHIP BETWEEN MYOFILAMENT PACKING DENSITY AND SARCOMERE LENGTH IN FROG STRIATED MUSCLE Philip W. Brandt, Philip W. ... The data are consistent with the assumption that the sarcomere of a fibril maintains a constant volume during changes in ... Since the distance between adjacent myofilaments is an inverse square root function of sarcomere length, the interaction of the ...
... May 19, 2023. by Zachariah Lindsey Sarcomere definition. A sarcomere is the functional unit of striated muscle. This ... What is a sarcomere? A sarcomere is a structural unit of a muscle fiber. It is the region between two adjacent Z-discs and ... Herein lies the sarcomeres main purpose. Sarcomeres are able to initiate large, sweeping movement by contracting in unison. ... What is the importance of sarcomeres in muscle function? Sarcomeres play a critical role in muscle function because they are ...
Includes a complete sarcomere with the configuration and function of thin filaments (actin, troponin, and tropomyosin) and ... Includes a complete sarcomere with the configuration and function of thin filaments (actin, troponin, and tropomyosin) and ... but instead slide past each other to shorten the sarcomere itself. Includes a transparent sheath representing the sarcoplasmic ...
Link to all annotated objects annotated to sarcomere. Link to all direct and indirect annotations to sarcomere. Link to all ... sarcomere. Ontology. cellular_component. Synonyms. None. Alternate IDs. None. Definition. The repeating unit of a myofibril in ... direct and indirect annotations download (limited to first 10,000) for sarcomere. Feedback. Contact the Planteome feedback if ...
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Detailed explanation-1: -A sarcomere is the basic contractile unit of a myocyte (muscle fibre). A sarcomere is composed of two ... Detailed explanation-2: -A sarcomere is the basic contractile unit of muscle fiber. Each sarcomere is composed of two main ... In fact, muscle is composed of millions of tiny sarcomeres, and each sarcomere shortens, thus resulting in muscular contraction ... The sarcomere consists of a bundle of myosin-containing thick filaments flanked and interdigitated with bundles of actin- ...
Plot -6, Savitri Market, Block C1, Janakpuri, New Delhi - 110058, India. ...
Sarcomere Mechanics in Capillary Endothelial Cells. Robert J. Russell; Shen-Ling Xia; Richard B. Dickinson; and Tanmay P. Lele ...
Sarcomere B. Muscle fiber C. Fascicle D. Myofibril - Skeletal Muscle Anatomy Quiz ...
sarcomere organization KRT19 cell differentiation involved in embryonic placenta development KRT2 keratinocyte development ...
Diabetes with heart failure increases methylglyoxal modifications in the sarcomere, which inhibit function. ... Diabetes with heart failure increases methylglyoxal modifications in the sarcomere, which inhibit function. ...
Supernumerary sarcomeres. Table 1. Comparative Features of Exercise-Related Pain (Open Table in a new window) ...
located_in sarcomere IDA Inferred from Direct Assay. more info. PubMed located_in sperm midpiece IEA Inferred from Electronic ...
In-situ sarcomere length measurement laser diffraction. .zip (. 177.7 kB. ). View file. Download file. ... In vivo sarcomere length (SL) measurements revealed that in TtnΔC1-2 mice the operating SL range of the LV is shifted towards ... Partial deletion of titins C-zone alters cardiac function by reducing the operating sarcomere length range. ... that the reduced working SLs reflect titins role in regulating diastolic stiffness by altering the number of sarcomeres in ...
Within muscle cells, titin is an essential component of structures called sarcomeres. . Sarcomeres are the basic units of ... Titin has several functions within sarcomeres. One of its most important jobs is to provide structure, flexibility, and ... Researchers suspect that these changes may disrupt titins interactions with other proteins within sarcomeres. Mutations may ... Titin also plays a role in chemical signaling and in assembling new sarcomeres. ...
Results: Thirteen SNVs and pathogenic variants were identified in the sarcomere gene, TTN, from 146 women with sPTL. DEPs of ... DEP of PCU mRNAs showed 22 genes associated with the sarcomere and three with the desmosome. Conclusion: The results ... Epi)genetic variants of the sarcomere-desmosome are associated with premature utero-contraction in spontaneous preterm labor ... and specifically on genes associated with sarcomeres and desmosomes. Methods: Pregnant cohort with biobank of pregnant tissues ...
each sarcomere extends from. one z line to another z line. the arrangement of these two give a banded appearance. actin, myosin ... when the sarcomeres shorten it causes the muscle to shorten. sliding of actin myofilaments past myosin myofilaments during ...
HCM is caused by mutations in sarcomere proteins, the contractile building blocks of the heart. Despite increased knowledge of ... HCM is caused by mutations in sarcomere proteins, the contractile building blocks of the heart. Despite increased knowledge of ... HCM is caused by mutations in sarcomere proteins, the contractile building blocks of the heart. Despite increased knowledge of ... HCM is caused by mutations in sarcomere proteins, the contractile building blocks of the heart. Despite increased knowledge of ...
Our findings suggest a novel therapeutic direction targeting sarcomere- cytoskeleton interactions to induce sarcomere re- ... Yet it is not known how TnT mutation causes dysfunction of sarcomere microdomains and how these events contribute to ... Small molecule-based activation of AMPK can restore TnT microdomain interactions, and partially recovers sarcomere protein ... Disrupted microdomain signaling impairs MYH7-mediated, AMPK-dependent sarcomere-cytoskeleton filament interactions and plasma ...
absence of sarcomere units and troponin?. 15. Why can certain drugs and hormones modulate the activity of smooth and cardiac ... 4. Know the substructure of the sarcomere basic contractile unit and what changes occur during skeletal muscle contraction.. 5. ...
Sarcomere Dynamics. Sarcomere Dynamics is creating a human-like robotic hand that can grasp a wide range of objects of varying ... Sarcomere Dynamics hands are a safe solution that provides high resilience and complex dexterous movements. Their technology ...

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