Chapter 9 (Homeostasis) Flashcards
homeostasis
The active process of maintaining a particular physiological parameter relatively constant.
motivation
The psychological process that induces or sustains a particular behavior
endotherm
An animal whose body temperature is regulated chiefly by internal metabolic processes. Examples include mammals and birds.
ectotherm
An animal whose body temperature is regulated by, and whose heat comes mainly from, the environment.
negative feedback
The property by which some of the output of a system feeds back to reduce the effect of input signals.
set point
The point of reference in a feedback system. An example is the temperature at which a thermostat is set.
set zone
The range of a variable that a feedback system tries to maintain.
intracellular compartment
The fluid space of the body that is contained within cells.
extracellular compartment
The fluid space of the body that exists outside the cells.
diffusion
The spontaneous 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 (often salt) 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.
hypovolemic thirst
A desire to ingest fluids that is stimulated by a reduction in volume of the extracellular fluid.
osmotic thirst
A desire to ingest fluids that is stimulated by loss of water from the extracellular compartment.
baroreceptor
A pressure receptor in the heart or a major artery that detects a change in blood pressure.
atrial natriuretic peptide (ANP)
A hormone, secreted by the heart, that normally reduces blood pressure, inhibits drinking, and promotes the excretion of water and salt at the kidneys.
vasopresin or arginine vasopresin
Also called antidiuretic hormone (ADH). A peptide hormone from the posterior pituitary that promotes water conservation and increases blood pressure.
angiotensin II
A hormone that is produced in the blood by the action of renin and that may play a role in the control of thirst.
circumventricular organ
Any of multiple distinct sites that lie in the wall of a cerebral ventricle and monitor the composition of the CSF.
aldosterone
A mineralocorticoid hormone, secreted by the adrenal cortex, that promotes the conservation of sodium by the kidneys.
nutrient
A chemical that is needed for growth, maintenance, and repair of the body but is not used as a source of energy.
glucose
An important sugar molecule used by the body and brain for energy.
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.