internal regulation

What is homeostasis

biological process that keeps body variables within fixed range (stable/balance)

What is a set point

value body works to maintain

What is negative feedback in homeostasis

process where body detects change and activates mechanisms to reverse it (restoring balance)

What is allostasis

Predictive regulation that anticipates future needs

What is basal metabolism

energy used to maintain a constant body temperature while at rest

What is poikilothermic (ectothermic)

idea that the body temperature matches environment

Amphibians, reptiles, and most fish are examples of poikilothermic (ectothermic) organisms

do not have internal psychological mechanism to regulate temperature; depends on environment

What is homeothermic (endothermic)

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

Body temperature regulation is predominantly dependent upon areas in ___ ___/___ ___ (___/___)

the preoptic area/anterior hypothalamus (POA/AH)

POA/AH receives input from ___ ___ throughout the body

temperature receptors

What triggers a fever

prostaglandins & histamines

POA/AH (hypothalamus) controls ___ ___

temperature responses

Mammals are made up of ___% water

70

Sufficient fluid is needed in ___ ___

circulatory system

Concentrations of ___ in water determine the ___ of all chemical reactions in the body

chemicals, rate

When you need water, the ___ sends signals to cells in ___; become more sensitive to anything related to water

hypothalamus, cortex

Thirst varies by ___; mainly managed by ___ and ___

situation, drinking, excretion

How to conserve

concentrated urine and reduced sweating

What is antidieurtic hormone (ADH/vasopressin)

Hormone that constricts blood vessels and promotes water retention

Vasopressin(ADH)

released by posterior pituitary

constricts blood vessels (BP up)

promotes water reabsorption in kidneys

produces concentrated urine

Certain neurons detect the loss of ___ and trigger ___ ___ to help restore the body to its normal state

water, osmotic thirst

What is osmotic thirst

crave water caused by high salt/solute concentration in blood

What occurs during osmotic thirst

sodium ions to spread through the blood and extracellular fluid of the cell (higher concentration of solutes outside the cell results in osmotic pressure, drawing water from the cell to the extracellular fluid)

What does OVLT and subfornical organ (SFO)

detect osmotic pressure and sodium content of the blood

What is hypovolemic thirst

Preference for slightly salty water after blood loss

Receptors in the OVLT, subfornical organ, stomach and elsewhere relay information to two areas of the hypothalamus: ___ ___ & ___ ___

supraoptic nucleus & paraventricular nucleus

Supraoptic nucleus and paraventricular nucleus controls how much/fast the ___ ___ releases ___

posterior pituitary, vasopressin

Receptors also relay information to the ___ ___ area which controls drinking

lateral preoptic

What is hypovolemic thirst

when body loses fluids and salt = thirsty and crave salt to recover; occurs when blood volume low

Kidneys release enzyme ___ which helps form ___ ___; other enzymes convert that into ___ ___

renin, angiotensin I, angiotensin II

What does angiotensin II do

tightens blood vessels to helps blood pressure rise

Osmatic thirst vs hypovolemic thirst crave what type of water

pure vs slightly salty

What is sodium specific hunger

strong craving for salty foods

Sodium specific hunger happens ___

automatically

How does body fix low sodium

adrenal glands release aldosterone

What does aldosterone do

tells kidneys, salivary glands, sweat glands to retain salt

Process of hormonal response to hypovolemic

low blood volume → kidney release renin into blood → proteins in blood produce angiotensin I → angiotensin I converts into angiotensin II → angiotensin II constricts blood vessels and stimulate cells in SFO to increase drinking

Receptors for osmotic thirst

OVLT, SFO, digestive tract

Receptors for hypovolemic thirst

OVLT, SFO, kidneys, blood vessels

Function of digestive system

breaks down food into smaller molecules that cells can use

Digestion begins in the ___; enzymes in saliva break down carbs

mouth

___ ___ and ___ in stomach digest proteins

hydochloric acid, enzymes

Enzymes in ___ intestines digest ___, ___, and ___ (absorbs into bloodstream)

small, proteins, fats, carbs

___ intestine absorbs ___ and ___ (lubricates for excretion)

large, water, mineral

Most mammals lose ___ after weaning which means they cannot digest ___

lactase, milk

Low lactase causes ___ and ___ from dairy; may have evolved to encourage ___

gas, cramps, weaning

Unsubstantial ___ may influence food selection

beliefs

Main signal to stop eating is ___ of stomach

distention (stretch)

___ ___ (___ ___ ___) conveys info about stomach walls stretching to brain

vagus nerve (cranial nerve X)

What is the duodenum

part of small intestine, site of initial absorption of significant amount of nutrients

Distention of fuofenum can also produce feelings of ___

fullness

What is cholecystokinin (CCK)

released by duodenum which helps regulate hunger

What is glucose

main product of digestion, enerygy source for body (main for brain)

___ and ___ regulate glucose flow into cells

insulin, glucose

Where does excess glucose go

liver and fat cells

What is insulin

pancreatic hormone that enables glucose to enter the cell

After a meal, what happens

blood glucose and insulin levels fall, gucose enters more slowly, hunger increases, pancreas releases glucagon

Insulin stays high

blood glucose drops, hunger increases

Inspite of high insulin levels

food rapidly deposited as fat and glycoge; causes weight gain

Characteristics of Type 1 diabete

low insulin, high blood sugar, eat more but lose weight

Characteristics of Type 2 diabete

most common (middle age), obesity and inactivity; insulin present, but cells resist it

What is leptin

Hormone released when fat stores are high to suppress hunger

Hypothalamic region containing hunger and satiety sensitive neurons

arcuate nucleus

Arcuate nucleus is a part of ___ containing two sets of neurons: Neurons sensitive to ___ and ___

hypothalamus, hunger signals, satiety signals

What is ghrenlin

neurotransmitter released in brain, acts on hypothalamus to increase appetite and triggers stomach contractions

Output from the arcuate nucleus goes to the ___ ___ of hypothalamus

paraventricular nucleus

Part of the hypothalamus inhibits the ___ ___ area important for eating

lateral hypothalamus

Axons from the ___ ___ cells of the arcuate nucleus deliver excitatory messages to ___ ___

satiety sensitive, paraventricular nucleus

What is melancortin

chemical important in limiting food intake; deficiencies lead to overeating

Where does melancortin get it’s info from

hunger cells of arcuate nucleus

Cells in the lateral hypothalamus release ____

orexin

What is orexin

increases animals’ persistence in seeking food

What is lateral hypothalamus

controls insulin secretion and alters taste responsiveness

Stimulation of lateral hypothalamus increases drive to eat, damage to this area causes ___ to food

aversions

Axon functions of lateral hypothalamus

affect taste sensation and salivation response to tastes, cause cortical cells to increase response to taste, smell, or sight of food, increase pituitary gland’s hormone, control digestive secretions

Output from the ventromedial hypothalamus (VMH) ___ feeding

inhibits

Damage to ventromedial hypothalamus (VMH) leads to ___ and ___ ___

overeating, weight gain.

___ stomach motility means it ___ faster than normal

increased, empties