Glossary terms will appear here.


Active transport - the movement of molecules across a cellular membrane requiring energy to do so

Allometry- systematic changes in body proportions with increasing species size.

Anabolism- metabolic pathway which requires energy and is associated with repair, regeneration and growth to assemble simple substances into more complex molecules required by the organism.

Anticoagulants- a substance that delays or prevents the clotting of blood

Autonomic control - refers to the involuntary control of blood flow in animals. Autonomic control is observed in some vertebrates to reduce the loss of heat at body surfaces. (refer to Randall, p682, Figure 16-14)

Basal Metabolic Rate (BMR)- the stable rate of energy metabolism measured in mammals and birds under conditions of minimum environmental and physiological stress.

Behavioral Regulation - type of regulation animals engage in when their behavior indicates a preference for a specific environment that favors optimal body temperature.

Bernoulli Effect- fluid pressure drops as fluid velocity increases

Bile - mixture of substance containing bile salts which emulsify and aid their digestion and absorption

Carrier mediated diffusion -the transport of a molecule across a membrane with the aid of ions

Catabolism- metabolic pathway which involves the breaking down of complex energy rich molecules into simpler ones.

Chylomicrons-protein-coated tiny droplets of triglycerides, phospholipids, and cholesterol formed within vesicles of absorptive cells from the digestion products of fats, monoglycerides, fatty acids, and glycerol

Core temperatures - refers to internal or deep-tissue body temperatures that can be relatively high in regional heterotherms due to muscle activity.

Countercurrent Heat Exchange - a specialized parallel arrangement of incoming arteries and outgoing veins forming a heat exchanger that conserves heat in the body core.

Critical thermal maximum - the temperature above which survival is not possible.

Crop - an expanded portion of the lower esophagus, used for temporarily storing food before it goes to the stomach

Crypt of Lieberkuhn- a circular depression around the base of each villus in the intestine

Digastric Stomach- the multichambered stomach of ruminants

Direct Calorimetry- measuring the metabolic rate of an organism by measuring the amount of energy released as heat over a given period.

Duodenum- the initial section of the small intestine, situated between pylorus of the stomach and the jejunum

Field Metabolic Rate (FMR) - average rate of energy utilization as the animal goes about its normal activities.

Folds of Kerckring/plica circularis - extensive fold of intestinal mucosa bearing villi

Gastrin- protein hormone tha is released by gastrin cells of the pyloric gland and induces gastric secretion and motility

Gizzard - a muscular organ in the upper alimentary canal in birds, churns mixture together, food and stones, to break down food into more digestible particles

Hess’ Law - the total energy released in the breakdown of a fuel to a given set of end products is always the same.

Hindgut - the terminal region of the alimentary canal, responsible for storing and eventually eliminating the remnants of digested food

Ileum - posterior section of the small intestine

Isometry - proportionality of shape regardless of size.

Isotopic Technique - measuring water fluxes in animals to determine metabolic rate.

Jejunum - the portion of the small intestine between the duodenum and the ileum

Kleiber’s Law - when metabolic rate of individuals of different species of mammals are plotted against body mass, the exponent relating metabolic rate to body mass is found to be approximately 0.75.

Lower critical temperature (LCT) - ambient temperature below which the BMR becomes insufficient to balance heat loss, resulting in falling body temperature.

Mass Specific Metabolic Rate - metabolic rate of a unit mass of tissue, sometimes called metabolic intensity

Metabolic Rate - the rate of conversion of chemical energy into heat.

Metabolism - sum total of all the chemical reactions occurring in an organism.

Midgut - major alimentary canal site for the chemical digestion of protein, fat, and carbohydrates

Monogastric Stomach - a stomach consisting of a single strong muscular tube or sac

Mucus - a protein containing a mixture of mucopolysaccharides secreted from specialized mucous membranes

Non-shivering thermogenesis - a process in which enzyme systems for fat metabolism are activated, breaking down and oxidizing conventional fats to produce heat.

Passive Diffusion - diffusion of substances across a membrane without the aid of another molecule or energy

Peristaltic Movement - a traveling wave of constriction in tubular tissue produced by contraction of circular muscle

Pharynx - the part of the gut between the mouth and esophagus

Pyloric Sphincter - sphincter guarding the opening of the stomach into the small intestine

Radula - a rasp-like structure in the mouth of many gastropods

Respirometry - measurement of an animal’s respiratory exchange, which can then be used to calculate metabolic rate.

Shivering thermogenesis - a means of using muscle contractions to liberate heat.

Specific Dynamic Action (SDA) - a marked increase in metabolism accompanies the processes of digestion and assimilation of food independently of other activities.

Specific heat conductance - a characteristic that varies with the nature of an animals body surface. Animals with high heat conductance in surface tissues are typically close to the temperature of their surroundings. Low conductance exists in surface tissues that are generally considered insulators, feathers, fur, or blubber. These elements reduce that conductance of body surfaces and slow the transfer of heat.

Standard Metabolic Rate (SMR) - an ectothermic animal’s resting and fasting metabolism at a given body temperature.

Surface area - a measurement of external body surfaces that decreases with increases in body mass.

Surface Hypothesis - idea that the metabolic rate of birds and mammals that maintain a more or less constant temperature should be proportional to body surface area because the rate of heat transfer between two compartments is proportional to their area of mutual contact.

Temperature difference - can affect the rate of transfer of heat. The closer an animal maintains its temperature to the ambient temperature, the less heat will flow into or out of its body.

Thermal neutral zone - that range of ambient temperatures within which an endotherm can control its temperature by passive measures and without elevating its metabolic rate.

Thermogenesis - the production of body heat by metabolic means such as fat metabolism or muscle contraction during shivering.

Villi/brush border- tiny cylindrical projections on a cell surface are increase surface area, frequently found on absorptive epithelia, a brush border is a free epithelia cell surface bearing numerous microvilli