Chapter 10 Flashcards
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
allostasis
adaptive way in which the body changes its set points depending on the situation (much of this control depends on hypothalamus)
basal metabolism
energy used to maintain a constant body temperature while at rest (requires about twice as much energy as all other body processes combined)
poikilothermic
amphibians, reptiles, and most fish; body temperature matches environment and is controlled by behavioural mechanisms
homeothermic
mammals and birds; use physiological mechanisms to maintain a nearly constant body temperature despite changes in temperature in the environment
Preoptic area/anterior hypothalamus, POA/AH
physiological changes that defend body temperature depend on these areas which send output to the hindbrain’s raphe nucleus which controls these mechanisms
Vasopressin aka antidiuretic hormone (ADH)
released by posterior pituitrary; raises blood pressure by constricting blood vessels which helps compensate for decreased blood volume when we don’t have enough water; enables kidneys to reabsorb water from urine
osmotic pressure
tendency of water to flow across a semi permeable membrane from areas of low concentration of solutes to areas of high concentration
osmotic thirst
certain neurons detect loss of water (i.e. eating salty food = + solutes in blood drawing water out of cells and into extracellular fluid) and trigger osmotic thirst which helps restore normal state
Organum vasculosum laminae terminalis (OVLT)
important for detecting osmotic pressure with subfornical organ (SFO), and salt content of the blood; receives input from brain itself and receptors in digestive tract, enabling brain to anticipate an osmotic need before the rest of the body experiences it
supraoptic nucleus
part of hypothalamus; messages from OVLT and SFO; controls rate at which posterior pituitary releases vasopressin
paraventricular nucleus
part of hypothalamus; messages from OVLT and SFO; controls rate at which posterior pituitary releases vasopressin
lateral preoptic area
part of hypothalamus that controls drinking
angiotensin II
constricts blood vessels, compensating for drop in blood pressure (renin splits angiotensinogen)
hypovolemic thirst
thirst based on low volume; need to restore lost salts and water
lactase
intestinal enzyme necessary for digesting lactose
lactose
sugar found in milk
sham-feeding
everything an animal swallows leaks out a tube connected to esophagus or stomach; does not produce satiety
vagus nerve
stomach conveys satiety messages to the brain via the vagus and splanchic nerves; conveys information about the stretching of the stomach walls
splanchic nerves
stomach conveys satiety messages to the brain via the vagus and splanchic nerves; convey information about the nutrient contents of the stomach
duodenum
part of the small intestine adjoining the stomach; releases OEA that stimulates vagus nerve
cholecystokinin (CCK)
reseased by any kind of food in the duodenum; limits meal size by 1) constricting sphincter muscles between stomach and duodenum, casing stomach to fill more quickly than usual, 2) stimulates vagus nerve to send signals to hypothalamus causing cells there to release a shorter version of CCK
Insulin
pancreatic hormone; enables glucose to enter the cells, except for the brain cells; insulin levels rise before a meal in preparation for a rush of additional glucose; high levels decrease appetite
Glucagon
pancreatic hormone; stimulates the liver to convert some of its stored glycogen to glucose to replenish low supplies in the blood
arcuate nucleus
area of hypothalamus; one set of neurons sensitive to hunger signals and one set sensitive to satiety signals
Ghrelin
neurotransmitter; binds to same receptors as growth hormone releasing hormone; released by stomach during a period of food deprivation where it triggers stomach contractions; acts on hypothalamus to decrease appetite and enhance learning
melanocortin
melanocortin receptors in the paraventricular nucleus are important for limiting food intake; deficiencies lead to over eating
neuropeptide Y
inhibitory transmitter; input from hunger-sensitive neurons of arcuate nucleus is inhibitory to PVN and setiety sensitive cells of arcuate nucleus itself
agouti-related peptide
inhibitory transmitter; input from hunger-sensitive neurons of arcuate nucleus is inhibitory to PVN and setiety sensitive cells of arcuate nucleus itself
lateral hypothalamus
input from PVN; compared to a crowded train station due to many clusters of neurons and passing axons; controls insulin secretion, taste responsiveness, and facilitates feeding
ventromedial hypothalamus (VMH)
output inhibits feeding; damage (and loss of output) can lead to drastically increased weight
bulimia nervosa
a condition in which people alternate between periods of binging and strict dieting (many people with bulimia also induce themselves to vomit)
