TEMPERATURE REGULATION AND THIRST

HOMEOSTASIS

temperature regulation and other biological processes that keep body variables within a fixed range.

SET POINT

a single value that the body works to maintain.

NEGATIVE FEEDBACK

Processes that reduce discrepancies from the set point.

ALLOSTOSIS

adaptive way in which the body anticipates needs depending on the situation, avoiding errors rather than just correcting them.

BASAL METABOLISM

the energy used to maintain a constant body temperature while at rest.

ECTOTHERMIC

depend on external sources for body heat instead of generating it themselves.

POIKILOTHERMIC

from Greek roots meaning "varied heat."

ENDOTHERMIC

generate enough body heat to remain significantly above the temperature of the environment.

HOMEOTHERMIC

from Greek roots meaning "same heat."

SHIVERING

Any muscle contractions, such as those of ___, generate heat. Second, decreased blood flow to the skin prevents the blood from cooling too much. The consequence is warm internal organs but cold skin.

GOOSE BUMPS

A third mechanism works well for most mammals, though not humans: When cold, they fluff out their fur to increase insulation; We humans also fluff out our "fur" by erecting the tiny hairs on our skin.

37 C

Body temperature.

41 C

Birds' body temperature.

PREOPTIC

near the optic chiasm, where the optic nerves cross.

PREOPTIC AREA/ANTERIOR HYPOTHALAMUS (POA/AH)

send output to the hindbrain's raphe nucleus, which controls the autonomic responses such as shivering, sweating, changes in heart rate and metabolism, and changes in blood flow to the skin.

FEVER

represents an increased set point for body temperature.

ESTRUS

during the fertile period of female rats; better in cooler environment.

PRO-ESTRUS

a day or 2 before the fertile period of female rats; better in warmer environment.

WALTER B. CANNON

Introduced Homeostasis.

BROWN ADIPOSE CELLS

cells that are more like muscle cells than like white fat cells; they burn fuel as muscle cells do, but release it directly as heat instead of as muscle contractions.

REPRODUCTIVE CELLS

require a cooler environment than the rest of the body.

PROSTAGLANDINS AND HISTAMINES

these chemicals are the cause of shivering, increased metabolism, and other processes that produce a fever.

39 C

you shiver or sweat whenever your temp deviates from that level.

VASOPRESSIN

raises blood pressure by constricting blood vessels.

ANTIDIURETIC HORMONE (ADH)

Vasopressin is also known as___; enables the kidneys to reabsorb water from urine and therefore make the urine more concentrated.

DIURESIS

urination.

OSMOTIC THIRST

caused by eating salty foods; a drive for water that helps restore the normal state; High solute concentration outside cells and relieved by pure water.

HYPOVOLEMIC THIRST

caused by losing fluid by bleeding or sweating; meaning thirst based on low volume; Low blood volume and relieved by Water containing solutes, near 0.15M.

OSMOTIC PRESSURE

the tendency of water to flow across a semipermeable membrane from the area of low solute concentration to the area of higher concentration.

INTRACELLULAR FLUID

inside the cell.

EXTRACELLULAR FLUID

outside the cell.

ORGANUM VASCULOSUM LAMINAE TERMINALIS (OVLT) & SUBFORNICAL ORGAN (SFO)

receptors around the third ventricle; detect osmotic pressure and the sodium content of the blood.

LATERAL PREOPTIC AREA

and surrounding parts of the hypothalamus control drinking.

SUPRAOPTIC NUCLEUS & PARAVENTRICULAR NUCLEUS (PVN)

control the rate at which the posterior pituitary releases vasopressin.

ANGIOTENSIN II

to form angiotensin I, which other enzymes convert to___; constricts the blood vessels, compensating for the drop in blood pressure.

RENIN

splits a portion off angiotensinogen.

ANGIOTENISINOGEN

a large protein in the blood, to form angiotensin I, which other enzymes convert to angiotensin II.

SODIUM-SPECIFIC HUNGER

an immediate strong preference for salty tastes.

ALDOSTERONE

a hormone that causes the kidneys, salivary glands, and sweat glands to retain salt.

MOLARITY

a measure of the number of particles per unit of solution, regardless of the size of each particle.

SEMIPERMEABLE MEMBRANE

one through which water can pass but solutes cannot.

THIRD VENTRICLE. ORGANUM VASCULOSUM LAMINAE TERMINALIS (OVLT), SUBFORNICAL ORGAN (SFO)

Receptors that detect osmotic pressure and the sodium content of the blood.

ORGANUM VASCULOSUM LAMINAE TERMINALIS (OVLT)

also receives input from receptors in the digestive tract, enabling it to anticipate an osmotic need before the rest of the body experiences it.

ALDOSTERONE & ANGIOTENSIN II

together they can change the properties of taste receptors on the tongue.