Regulation Flashcards
allostasis
adaptive way the body anticipates needs depending on the situation
basal metabolism
energy used to maintain constant body temp at rest
poikilothermic
ectothermic
body temp matches that of environment
amphibians, reptiles, fish
organism lacks mech of internal reg
homeothermic
endothermic
use of internal mechs to maintain almost constant body temp
mammals and birds
requires energy and fuel
sweating/panting decrease temp
shivering/fluffing fur increase temp
preoptic area/anterior hypothalamus
POA/AH
responsible for body temp regulation
receieves input from immune system, skin, and brain
vasopressin
hormone released by posterior pituitary raises blood pressure helps compensated for decreased water volume antidiuretic hormone kidneys reabsorb water
osmotic thirst
results from eating salty foods
hypovolemic thirst
results from loss of fluids due to sweating or bleeding
osmotic pressure
solutes inside and outside cell create
water travels across semi-permeable membrane from area of low solute to an area of high
occurs when solutes are more concentrated on one side
draws water from the cell
OVLT
detects osmotic pressure
relays information to supraoptic nucleus and paraventricular nucleus
vagus nerve
Conveys information about the stretching of
the stomach walls to the brain
Splanchnic nerves
Convey information about the nutrient
contents of the stomach
Duodenum
Part of the small intestine
initial absorption of nutrients
Distention of the duodenum can produce feelings of satiety
releases the hormone cholecystokinin (CCK), which helps to regulate hunger
Cholecystokinin (CCK)
released by duodenum
regulates hunger by:
Closing the sphincter muscle between the
stomach and duodenum and causing the
stomach to hold its contents and fill faster
Stimulating the vagus nerve to send a
message to the hypothalamus
Glucose
Main product of digestion Important source of energy for the body Nearly the only fuel used by the brain Excess glucose enters the liver and fat cells
BLOOD GLUCOSE LEVES DECLINE, INSULIN INCREASES
Insulin
Pancreatic hormone that enables glucose
to enter the cell (except brain)
After a meal: – Blood glucose levels fall – Insulin levels drop – Glucose enters cells more slowly – Hunger increases – Pancreas releases glucagon
Glucagon
Hormone released by the pancreas when glucose levels fall
Stimulates the liver to convert some of its
stored glycogen to glucose to replenish low supplies in the blood
Leptin
peptide
signals the brain to increase or decrease eating
Low levels of leptin increase hunger
High levels reduce eating and increase
physical and immune system activity
arcuate nucleus
receives information from all parts of the body regarding hunger part of the hypothalamus containing two sets of neurons Neurons sensitive to hunger signals Neurons sensitive to satiety signals
Ghrelin
Neurotransmitter released in the brain
– Acts on the hypothalamus to increase appetite
– Triggers stomach contractions
Melanocortin
chemical important in limiting food intake
Deficiencies of this receptor lead to overeating
