(9/825) Integration and regulation of cardiovascular function.
New methods in molecular biology and genetics have made possible many of the dramatic advances in physiological research that have occurred in recent years. For those of us who spend most of our time in the research laboratory, it si sometimes difficult to avoid a research-oriented, reductionist mind-set when discussing physiology with students. This article illustrates, with a few examples, the importance of conveying a "big picture" conceptual framework before discussing the details of cardiovascular physiology. Also, I have chosen examples from cardiac output and blood pressure regulation that show the importance of discussing cardiovascular physiology in terms of feedback control systems and integrating information from other areas, such as renal and endocrine physiology. Finally, I have highlighted the importance of two principles that I believe are often underemphasized in teaching physiology: mass balance and time dependence of physiological control systems. (+info)
(10/825) Teaching the principles of hemodynamics.
Knowledge of hemodynamic principles is crucial to an understanding of cardiovascular physiology. This topic can be effectively taught by discussing simple physical principles and basic algebraic equations. A variety of examples from everyday observations can be used to illustrate the physical principles underlying the flow of blood through the circulation, thereby giving the student an experiential feel for the topic in addition to an understanding of theory. Moreover, opportunities abound for showing how each hemodynamic principle can explain one or another functional feature of the cardiovascular system or a cardiovascular pathophysiological state. Thus hemodynamics can be used as an organizational thread to tie together other aspects of cardiovascular physiology. (+info)
(11/825) Teaching vascular adaptations to mechanical stress.
Blood vessels change their number and structure in attempt to meet tissue demands for blood flow while simultaneously controlling mechanical stresses. A great deal of information is emerging in this field, especially concerning the role of the endothelium and signaling pathways for mechanotransduction. While not delving too deeply into the rapidly changing details, the students can be introduced to this exciting field by describing the structural changes that take place and outlining the major theories that are being investigated. The applications to peripheral vascular disease, myocardial infarctions, hypertension and tumor growth are readily apparent. (+info)
(12/825) Common misconceptions that arise in the first-year medical physiology curriculum concerning heart failure.
There are a number of misconceptions that first-year medical students have concerning the pathophysiology of heart failure. These stem from 1) a poor definition of heart failure, 2) a lack of care in distinguishing between similar but distinct concepts, and 3) the inability to recognize the relationship between the various stages of heart failure and the clinical manifestation of the disease. In this paper we provide a list of some of the misconceptions that we have encountered, some explanations of the distinctions to be made, and some of the rationale behind current surgical procedures and drug treatment. The misconceptions include failing to differentiate between the Frank-Starling mechanism and cardiac dilation as well as not grasping the significance that changes in cardiac beta-receptor function have in limiting the positive inotropic actions of circulating catecholamines. Finally, we review some of the altered neurohumoral mechanisms in heart failure and explain the basis for some common therapeutic approaches, including the use of angiotensin-converting enzyme inhibitors, in this disease. (+info)
(13/825) Biomedical device design discovery team approach to teaching physiology to undergraduate bioengineering students.
Teaching effectiveness is enhanced by generating student enthusiasm, by using active learning techniques, and by convincing students of the value of acquiring knowledge in the area of study. We have employed a technique to teach physiology to bioengineering students that couples students' enthusiasm for their chosen field, bioengineering, with an active learning process in which students are asked to design a biomedical device to enhance, replace, or create a new cellular or organ system function. Each assignment is designed with specific constraints that serve to direct students' attention to specific areas of study and that require students to create original designs. Preventing students from using existing designs spurred student invention and enthusiasm for the projects. Students were divided into groups or "design discovery teams" as might be done in a biomedical device industry setting. Students then researched the physiological issues that would need to be addressed to produce an acceptable design. Groups met with faculty to brainstorm and to obtain approval for their general design concepts before proceeding. Students then presented their designs to the instructors in a structured, written outline form and to the class as a 10-minute oral presentation. Grades were based on the outline, oral presentation, and peer evaluations (group members anonymously rated contributions of other members of their team). We believe that this approach succeeded in generating enthusiasm for learning physiology by allowing the students to think creatively in their chosen field of study and that it has resulted in students developing a more thorough understanding of difficult physiological concepts than would have been achieved with a traditional didactic lecture approach. (+info)
(14/825) Electrophysiology of the undergraduate neuroscience student: a laboratory exercise in human electromyography.
A laboratory exercise is described in which students in a neuroscience, psychobiology, or similar laboratory course record the electromyogram (EMG) from themselves, using surface electrodes (placed on the skin). This exercise is intended to give students a firsthand demonstration that electrical activity is produced within them and to allow the students to use this activity to study biological and psychological concepts. The students study the nature of the EMG (changes with tension and the temporal relationship with limb movement) and the concepts of flexion and extension, reaction time, and patellar ("knee jerk") reflex. In postlaboratory evaluations, undergraduate introductory neuroscience students indicated that they appreciated the opportunity to record electrical activity from their own bodies. The students found the exercise enjoyable, believed that they had learned from it, and indicated that it should be a regular part of the course. If electrophysiology in animal preparations is already part of the course, this exercise requires minimal additional equipment, some of which is easily constructed and the reminder of which is available inexpensively. (+info)
(15/825) A simple, inexpensive method for teaching how membrane potentials are generated.
We have developed a simple laboratory exercise that uses an inexpensive dialysis membrane (molecular weight cutoff = 100) to illustrate the generation of membrane potentials (Vm) across plasma membranes of animal cells. A piece of membrane approximately 2.0 cm2 is mounted in an Ussing-like chamber. One chamber half is designated cytosol and the other half external. Chamber sidedness helps students relate their findings to those of real cells. As in real cells, outward directed K+ concentration gradients [high cytosolic K+ concentration ([K+]c) and low extracellular K+ concentration] generate cytosol electrically negative Vm with a slope of approximately -45 mV/decade change in [K+]c. The polarity of Vm reflects the outward flow of potassium ions because flow of the larger counterion, H2PO4-, is restricted to the pores in the membrane. A slope less than Nernstian (<59 mV/decade) suggests that the membrane is slightly permeable to H2PO4-. Importantly, this facilitates teaching the use of the Nernst equation to quantify the relationship between ion concentration ratios across membranes and magnitude of Vm. For example, students use their data and calculate a permeability ratio PK/PH2PO4 that corresponds to a slope of approximately 24% less than Nernstian. This calculation shows that Nernstian slopes are achieved only when permeability to the counterion is zero. Finally, students use the concept of membrane capacitance to calculate the number of ions that cross the membrane. They learn where these ions are located and why the bulk solutions conform to the principle of electroneutrality. (+info)
(16/825) Construction of a model demonstrating cardiovascular principles.
We developed a laboratory exercise that involves the construction and subsequent manipulation of a model of the cardiovascular system. The laboratory was designed to engage students in interactive, inquiry-based learning and to stimulate interest for future science study. The model presents a concrete means by which cardiovascular mechanics can be understood as well as a focal point for student interaction and discussion of cardiovascular principles. The laboratory contains directions for the construction of an inexpensive, easy-to-build model as well as an experimental protocol. From this experience students may gain an appreciation fo science that cannot be obtained by reading a book or interacting with a computer. Students not only learn the significant physiological concepts but also appreciate the importance of laboratory experimentation for understanding complex concepts. Model construction provides a hands-on experience that may substantially improve performance in science processes. We believe that model construction is an appropriate method for teaching advanced concepts. (+info)