ingestive behaviors

system variable

the physiological property that is being controlled by the regulatory mechanism (air temp)

set point

the optimal value for the system variable (temp setting)

detector

a sensor to measure changes in the set point (thermostat)

correctional mechanism

a mechanism for changing the system variable in order to restore it to the set point (electric heater)

negative feedback

a mechanism that works to shut down the action of the correctional mechanism (heat)

satiety mechanism

brain mechanism that causes the cessation of hunger or thirst signals when the body has adequate nutrients from food or replenishment of water

intracellular fluid

detects fluid inside our cells and helps to maintain the balance of salts and fluids around our cells

intravascular fluid

we can detect the volume of intravascular fluid in order to maintain the functions of the heart and circulatory system

osmoreceptor

stretch sensitive neuron

signal for osmometric thirst

changes in cell volume causes in the membrane

volumetric thirst

detects a decrease in blood plasma levels; multiple things can cause these changes: evaporation of water through skin, loss of blood, vomiting, diarrhea

angiotensin

triggers drinking and induces a salt appetite; also causes kidneys to increase blood pressure and conserve intravascular fluid in order to protect the body

baroreceptors

in the heart rate stretch sensitive and also detect changes in blood volume

ovlt and sfo

two structures that monitor osmotic thirst; located outside of the blood brain barrier

glycogen

main fuel; complex carbohydrate

insulin

in the liver triggers the conversion of glucose to glycogen for storage

glucagon

can then convert glycogen to glucose when needed to stabilize blood sugar

adipose

fat tissue that contains cells that concert nutrients from the blood into triglycerides or back into fuel for the body when needed

triglycerides

a type of fat in the body that are essential for energy but can be harmful in excess; most common type of fat in the body and come from food, especially butter, oils, and other fats

empty digestive

the pancreas stops secreting insulin and starts secreting glucagon; glucose become reserved for the brain; we begin drawing from short and long term reserves; proteins will eventually be converted for fuel

available digestive

glucose levels rise, causing the pancreas to stop secreting glucagon and start making insulin; this allows the cells in the body to use glucose as fuel (and for the projection of glycogen); amino acids are used to build proteins or stored as fat; fat from food is stored for later

ghrelin

hormone that also acts as a neuropeptide (neurotransmitter for signaling neurons); released by the stomach and other parts of the gastrointestinal system when they are empty; binds to the hypothalamus to help initiate feeding or food-seeking; ghrelin increases before each meal; injections stimulate thoughts of eating

satiation

occurs when we are full after a mean or beyond the point of full/satisfied

satiety signals

the signals for satiation

medulla

receives taste info from the togue, input from the intestines and stomach and contains detectors for glucose to help signal the brains need for glucose when levels fall, active in hungry rats and can signal the need to pull nutrients from adipose tissue

dorsal

Relating to the back or posterior of a structure

lateral hypothalamus

lesions stops eating or drinking, while electrical stimulation causes voracious eating and drinking

ventromedial hypothalamus

lesions produce overeating and electrical stimulation suppress feeding

mch and orexin

neurons in the lateral hypothalamus stimulate hunger

neuropeptide y (npy)

neurons that release this are found in the arcuate nucleus of the hypothalamus; increased when animals are food deprived and decrease following a meal; infusion into the hypothalamus drives eating; thought to be affected by signals from ghrelin (released from stomach)

bariatric surgeries

reduce the amount of food that can be taken in at one time; gastric band; gastric bypass