Air Sacs: Thin-walled sacs or spaces which function as a part of the respiratory system in birds, fishes, insects, and mammals.Air: The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.Yolk Sac: The first of four extra-embryonic membranes to form during EMBRYOGENESIS. In REPTILES and BIRDS, it arises from endoderm and mesoderm to incorporate the EGG YOLK into the DIGESTIVE TRACT for nourishing the embryo. In placental MAMMALS, its nutritional function is vestigial; however, it is the source of INTESTINAL MUCOSA; BLOOD CELLS; and GERM CELLS. It is sometimes called the vitelline sac, which should not be confused with the VITELLINE MEMBRANE of the egg.Hoarseness: An unnaturally deep or rough quality of voice.Reindeer: A genus of deer, Rangifer, that inhabits the northern parts of Europe, Asia, and America. Caribou is the North American name; reindeer, the European. They are often domesticated and used, especially in Lapland, for drawing sleds and as a source of food. Rangifer is the only genus of the deer family in which both sexes are antlered. Most caribou inhabit arctic tundra and surrounding arboreal coniferous forests and most have seasonal shifts in migration. They are hunted extensively for their meat, skin, antlers, and other parts. (From Webster, 3d ed; Walker's Mammals of the World, 5th ed, p1397)Larynx: A tubular organ of VOICE production. It is located in the anterior neck, superior to the TRACHEA and inferior to the tongue and HYOID BONE.Dinosaurs: General name for two extinct orders of reptiles from the Mesozoic era: Saurischia and Ornithischia.Air Pollutants: Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or material. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.Air Pollution: The presence of contaminants or pollutant substances in the air (AIR POLLUTANTS) that interfere with human health or welfare, or produce other harmful environmental effects. The substances may include GASES; PARTICULATE MATTER; or volatile ORGANIC CHEMICALS.Poultry Diseases: Diseases of birds which are raised as a source of meat or eggs for human consumption and are usually found in barnyards, hatcheries, etc. The concept is differentiated from BIRD DISEASES which is for diseases of birds not considered poultry and usually found in zoos, parks, and the wild.Endolymphatic Sac: The blind pouch at the end of the endolymphatic duct. It is a storage reservoir for excess ENDOLYMPH, formed by the blood vessels in the membranous labyrinth.Vocalization, Animal: Sounds used in animal communication.Neck Muscles: The neck muscles consist of the platysma, splenius cervicis, sternocleidomastoid(eus), longus colli, the anterior, medius, and posterior scalenes, digastric(us), stylohyoid(eus), mylohyoid(eus), geniohyoid(eus), sternohyoid(eus), omohyoid(eus), sternothyroid(eus), and thyrohyoid(eus).Respiratory System: The tubular and cavernous organs and structures, by means of which pulmonary ventilation and gas exchange between ambient air and the blood are brought about.Thorax: The upper part of the trunk between the NECK and the ABDOMEN. It contains the chief organs of the circulatory and respiratory systems. (From Stedman, 25th ed)Anal Sacs: A pair of anal glands or sacs, located on either side of the ANUS, that produce and store a dark, foul-smelling fluid in carnivorous animals such as MEPHITIDAE and DOGS. The expelled fluid is used as a defensive repellent (in skunks) or a material to mark territory (in dogs).Turkeys: Large woodland game BIRDS in the subfamily Meleagridinae, family Phasianidae, order GALLIFORMES. Formerly they were considered a distinct family, Melegrididae.Mycoplasma Infections: Infections with species of the genus MYCOPLASMA.Embolism, Air: Blocking of a blood vessel by air bubbles that enter the circulatory system, usually after TRAUMA; surgical procedures, or changes in atmospheric pressure.Air Microbiology: The presence of bacteria, viruses, and fungi in the air. This term is not restricted to pathogenic organisms.Finches: Common name for small PASSERIFORMES in the family Fringillidae. They have a short stout bill (BEAK) adapted for crushing SEEDS. Some species of Old World finches are called CANARIES.Songbirds: PASSERIFORMES of the suborder, Oscines, in which the flexor tendons of the toes are separate, and the lower syrinx has 4 to 9 pairs of tensor muscles inserted at both ends of the tracheal half rings. They include many commonly recognized birds such as CROWS; FINCHES; robins; SPARROWS; and SWALLOWS.Diving: An activity in which the organism plunges into water. It includes scuba and bell diving. Diving as natural behavior of animals goes here, as well as diving in decompression experiments with humans or animals.Skull: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.Poultry: Domesticated birds raised for food. It typically includes CHICKENS; TURKEYS, DUCKS; GEESE; and others.Trachea: The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.Acoustic Impedance Tests: Objective tests of middle ear function based on the difficulty (impedance) or ease (admittance) of sound flow through the middle ear. These include static impedance and dynamic impedance (i.e., tympanometry and impedance tests in conjunction with intra-aural muscle reflex elicitation). This term is used also for various components of impedance and admittance (e.g., compliance, conductance, reactance, resistance, susceptance).