Chapter_9_Book

homeostasis

The maintenance of a relatively constant internal physiological environment.

motivation

The psychological process that induces or sustains a particular behavior.

thermoregulation

The active process of maintaining a relatively constant internal temperature through behavioral and physiological adjustments.

endotherm

An animal whose body temperature is regulated chiefly by internal metabolic processes.

ectotherm

An animal whose body temperature is regulated by, and whose heat comes mainly from, the environment.

negative feedback

The process whereby a system monitors its own output and reduces its activity when a set point is reached.

set point

The point of reference in a feedback system.

set zone

The optimal range of a variable that a negative feedback system tries to maintain.

allostasis

The varying behavioral and physiological adjustments that an individual makes in order to maintain optimal functioning of a regulated system in the face of changing environmental stressors.

osmotic thirst

A desire to ingest fluids that is stimulated by high concentration of solute (like salt) in the extracellular compartment.

hypovolemic thirst

A desire to ingest fluids that is stimulated by a reduction in volume of the extracellular fluid.

intracellular compartment

The fluid of the body that is contained within cells.

extracellular compartment

The fluid of the body that exists outside the cells.

diffusion

The passive spread of solute molecules through a solvent until a uniform solute concentration is achieved.

osmosis

The passive movement of a solvent, usually water, through a semipermeable membrane until a uniform concentration of solute is achieved on both sides of the membrane.

osmotic pressure

The tendency of a solvent to move across a membrane in order to equalize the concentration of solute on both sides of the membrane.

glycogen

A complex carbohydrate made by the combining of glucose molecules for a short-term store of energy.

insulin

A pancreatic hormone that lowers blood glucose, promotes energy storage, and facilitates glucose utilization by cells.

glucagon

A pancreatic hormone that converts glycogen to glucose and thus increases blood glucose.

basal metabolism

The use of energy for processes such as heat production, maintenance of membrane potentials, and all the other basic life-sustaining functions of the body.

adipose tissue

Commonly called fat tissue; tissue made up of fat cells.

ketone

An organic molecule, derived from the breakdown of fat, that can be used by cells as an energy source.

diabetes mellitus

A condition characterized by excessive glucose in the blood and urine and by reduced glucose utilization by body cells, caused by the failure of insulin to induce glucose absorption.

leptin

A peptide hormone released by fat cells that provides information about the body’s long-term energy reserves.

ghrelin

A peptide gut hormone believed to act on the hypothalamic appetite system to increase hunger.

PYY3-36

A peptide gut hormone believed to act on the hypothalamic appetite system to suppress appetite.

bariatric surgery

Surgical procedures that help with weight loss by making changes to the digestive system.