Quiz Study 9

Chapter 9

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