Quiz Study 9

allostasis

allostasis

• refers to the adaptive way in which the body anticipates needs depending on the situation

• help the body avoid errors instead of just correcting them

basal metabolism

• energy used to maintain a constant body temperature while a rest

ectothermic

• the idea that the body temperature matches that of the environment

• aka poikilothermic

endothermic

• use of internal physiological mechanisms to maintain an almost constant body temperature

• aka homeothermic

homeostasis

• various biological processes that keep body variables within a fixed range

negative feedback

• processes that reduce discrepancies from the set point

preoptic area/anterior hypothalamus, or POA/AH

• body temperature regulation is dependent on this

• receives input from temperature receptors throughout the body

set point

• a single value that the body works to maintain

aldosterone

• a corticosteroid hormone which stimulates absorption of sodium by the kidneys and so regulates water and salt balance

antidiuretic hormone (ADH)

• raises blood pressure by constricting blood vessels

• helps to compensate for decreased water volume

• example: vasopressin

osmotic pressure

• created by solutes inside and outside a cell

• occurs when solutes are more concentrated on one side of the membrane -certain neurons detect the loss of water and trigger osmotic thirst to help restore the body to its normal state

vasopressin

• a hormone released by the posterior pituitary

• enables the kidneys to reabsorb water and excrete highly concentrated urine

anorexia nervosa

• Eating disorder characterized by a refusal to eat enough to maintain a healthy body weight

bulimia nervosa

• eating disorder in which people alternate between extreme dieting and binges of overeating

cholecystokinin (CKK)

• released by the duodenum to regulate hunger

• closes 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 that releases a chemical similar to CCK

lactase

• intestinal enzyme necessary for metabolizing lactose

• declining levels of lactase may be an evolutionary mechanism to encourage weaning

lactose

• the sugar found in milk

lateral hypothalamus

• controls insulin secretion and alters taste responsiveness

• stimulation of this increases the drive to eat

• damage to this area cause aversion to food

leptin

• produced by the body's fat cells to signal the brain to increase or decrease eating

• low levels increase hunger, high levels reduce eating and increase physical and immune system activity

neuropeptide Y (NPY)

• inhibitory transmitter

• blocks the satiety action of the paraventricular nucleus and provokes overeating

vagus nerve

• conveys information about the stretching of the stomach walls to the brain

• *the main signal to stop eating is the distention of the stomach

ventromedial hypothalamus (VMH)

• output from the VMH inhibits feedings

• damage to the nucleus leads to overeating and weight gain