Exam 3: Homeostasis

Question 1

maintenance of a relatively stable, balanced internal environment

Answer 1

homeostasis

Question 2

psychological process that induces or sustains a particular behavior

Answer 2

motivation

Question 3

what is motivation a mismatch between

Answer 3

actual internal state and regulated state which produces a drive to restore the balance

Question 4

4 important concepts in homeostasis

Answer 4

negative feedback
redundancy
behavioral homeostasis
allostasis

Question 5

negative feedback

Answer 5

deviation from set point triggers a compensatory action of the system

• restoring desired value turns off the response
  ex: thermostat in house

Question 6

redundancy

Answer 6

the body has multiple systems for regulating internal environment
allows for compensation if one monitoring system fails

Question 7

the body has multiple systems for generating heat and cooling the body if it is overheated - give examples of each

Answer 7

heat: burn fat, shiver, blood flow
cold: sweat

Question 8

Redundancy can complicate things how?

Answer 8

complicates diagnosis
- dopamine neuron dies off early on no motor symptoms - other systems can help pick this up with serotonin which hides some symptoms - makes it hard

Question 9

3 behavioral regulation changes

Answer 9

• exposure of body surface
• external insulation
• surroundings (sun, shade)

Question 10

what helps maintain homeostasis

Answer 10

allostasis

Question 11

allostasis

Answer 11

process of achieving stability through physiological and/or behavioral changes

Question 12

ex of allostasis

Answer 12

heart rate and blood pressure are continually shifted to accommodate current or anticipated activity levels

• allows body to keep functioning
• up late doing paper and bf breaks up with you this helps you keep going and finish paper

Question 13

water shuttles between what two compartments

Answer 13

intracellular and extracellular compartments

intracellular: fluid contained within the cells
extracellular: fluid outside the cells

Question 14

interstitial fluid

Answer 14

between the cells

water, Na, amino acids, hormones, sugars

Question 15

blood plasma

Answer 15

protein rich fluid that carries red and white blood cells

Question 16

water moves in and out of cells through specialized channels called…

Answer 16

aquaporins

Question 17

osmolality

Answer 17

concentration of solute in a solution

Question 18

isotonic solution

Answer 18

salt balanced in and out of the cell

salt solution about 0.9% - same as in mammalian fluids

Question 19

hypertonic solution

Answer 19

more salt outside cell - water wants to leave the cell

Question 20

hypotonic solution

Answer 20

has less salt than an isotonic solution

Question 21

diffusion

Answer 21

passive spread of molecules of a substance in another substance (solvent) until a uniform concentration is achieved

Question 22

osmosis

Answer 22

passive movement of solvent through semipermeable membrane between solutions of different solute concentration until both sides equal

Question 23

osmotic pressure

Answer 23

the force that pushes or pulls water across the membrane

Question 24

2 types of thirst

Answer 24

osmotic thirst and hypovalemic thirst

Question 25

osmotic thirst

Answer 25

stimulated by high extracellular solute concentration

Question 26

hypovalemic thirst

Answer 26

stimulated by low extracellular fluid volume | aka volumetric thirst

Question 27

baroreceptors

Answer 27

major blood vessels that detect any pressure drop from fluid loss

Question 28

osmosensory neurons

Answer 28

detect increased saltiness of extracellular fluid

Question 29

what happens when you get an increase in interstitial solute concentration?

Answer 29

caused by sodium being absorbed into the blood plasma draws water out of cells, the cells shrink in volume - cells respond to changes in concentration of interstitial fluid

Question 30

what does the shrinkage of cells alter?

Answer 30

osmosensory neuron firing rate

Question 31

osmoreceptors

Answer 31

send signals to drink more water when cells shrink | detect and respond to changes in how much the membrane of the cell stretches

Question 32

circumventricular organs in the hypothalamus that respond to changes in osmotic pressure

Answer 32

osmosensory neurons

Question 33

lamina terminalis

Answer 33

anterior boundary of hypothalamus containing SFO and OVLT

Question 34

osmotic thirst =

Answer 34

OVLT

Question 35

circumventricular organs have fenestrated capillaries..

Answer 35

lacking BBB- allows neurons in these regions to monitor salt concentration and hormones in bloodstream

Question 36

OVLT neurons project to...

Answer 36

median preoptic area of the hypothalamus

Question 37

vasopressin produced in the _____ and stored in the _____

Answer 37

hypothalamus | posterior pituitary

Question 38

vasopressin associated with...

Answer 38

jealousy | water conservation - released when dehydrated

Question 39

when is vasopressin released?

Answer 39

hypothalamic and OVLT osmoreceptors detect increase in solute concentration in blood plasma which causes the release of vasopressin

Question 40

2 ways vasopressin conserves water

Answer 40

reduces blood flow to extremities reabsorbs water from urine into bloodstream - binding of vasopressin to kidneys - more aquaporins inserted into kidney membrane to pull more water out of the urine

Question 41

Osmotic thirst: what happens when you eat something salty?

Answer 41

- hypothalamus detects higher solute concentration in blood - hypothalamus creates sensations of thirst - posterior pituitary releases more ADH (vasopressin) - person drinks water, ADH stimulates kidneys to reabsorb more water

Question 42

Osmotic thirst: what happens if drink too much water?

Answer 42

- hypothalamus detects low solute concentration (says lets not release vasopressin bc too much water) - pituitary releases less ADH - kidneys reabsorb less water and excrete as urine

Question 43

what is hypovolemic thirst triggered by?

Answer 43

fluid loss ex: bleeding, vomiting, diarrhea body fluid ion concentration remains the same

Question 44

what monitors blood volume and induces volumetric thirst?

Answer 44

detector cells in heart and kidneys (stretch sensitive baroreceptors)

Question 45

what do kidneys produce in response to low volume?

Answer 45

angiotensin II

Question 46

angiotensin II

Answer 46

initiates drinking and salt appetite | induces eating and drinking

Question 47

what is the hormone signal for hypovolemic thirst?

Answer 47

angiotensin II - cannot cross BBB - acts in SFO to produce thirst

Question 48

SFO

Answer 48

circumventricular organ

Question 49

SFO neurons project to the ______ to _____

Answer 49

median preoptic nucleus of he hypothalamus | induce thirst

Question 50

neurons in SFO and OVLT send axons to...

Answer 50

part of the lamina terminalis | - the median preoptic nucleus

Question 51

median preoptic nucleus

Answer 51

acts as integrating system for most of the stimuli for osmotic and volumetric thirst

Question 52

neural mechanism volumetric thirst

Answer 52

- drop in fluid volumes causes release of angiotensin II which activates SFO neurons which send axons to median preoptic nucleus

Question 53

neural mechanism of osmotic thirst

Answer 53

solute concentration in blood changes which is picked up by OVLT osmoreceptors - they stretch or contract according to these changes and send axons to median preoptic nucleus

Question 54

hypovolemic thirst path

Answer 54

- dec blood volume - dec BP - inc angiotensin II - stimulates thirst center of hypothalamus - inc thirst from SFO - water taken in dec blood osmolality

Question 55

osmotic thirst path

Answer 55

- inc blood osmolality - dry mouth and osmoreceptors in hypothalamus (signals you should start drinking) - thirst center stimulated in hypothalamus, activates median preoptic nucleus - inc thirst - inc water intake - dec blood osmolality

Question 56

How does your brain know when to stop drinking?

Answer 56

anterior cingulate cortex

Question 57

anterior cingulate cortex

Answer 57

shows strong activation during osmotic thirst activation: immediately diminishes following drinking - subjective thirst

Question 58

lamina terminalis

Answer 58

takes longer to decrease | - reflects biological thirst

Question 59

molecules in gut

Answer 59

determine how hydrated it will be | - alerts osmoreceptors when drink water in OVLT that inc in water, ACC shuts down