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Neuroscience I > Exam 3: Homeostasis > Flashcards

Exam 3: Homeostasis Flashcards

1
Q

maintenance of a relatively stable, balanced internal environment

A

homeostasis

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2
Q

psychological process that induces or sustains a particular behavior

A

motivation

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3
Q

what is motivation a mismatch between

A

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

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4
Q

4 important concepts in homeostasis

A

negative feedback
redundancy
behavioral homeostasis
allostasis

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5
Q

negative feedback

A

deviation from set point triggers a compensatory action of the system

  • restoring desired value turns off the response
    ex: thermostat in house
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6
Q

redundancy

A

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

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7
Q

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

A

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

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8
Q

Redundancy can complicate things how?

A

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

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9
Q

3 behavioral regulation changes

A
  • exposure of body surface
  • external insulation
  • surroundings (sun, shade)
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10
Q

what helps maintain homeostasis

A

allostasis

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11
Q

allostasis

A

process of achieving stability through physiological and/or behavioral changes

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12
Q

ex of allostasis

A

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
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13
Q

water shuttles between what two compartments

A

intracellular and extracellular compartments

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

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14
Q

interstitial fluid

A

between the cells

water, Na, amino acids, hormones, sugars

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15
Q

blood plasma

A

protein rich fluid that carries red and white blood cells

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16
Q

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

A

aquaporins

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17
Q

osmolality

A

concentration of solute in a solution

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18
Q

isotonic solution

A

salt balanced in and out of the cell

salt solution about 0.9% - same as in mammalian fluids

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19
Q

hypertonic solution

A

more salt outside cell - water wants to leave the cell

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20
Q

hypotonic solution

A

has less salt than an isotonic solution

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21
Q

diffusion

A

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

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22
Q

osmosis

A

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

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23
Q

osmotic pressure

A

the force that pushes or pulls water across the membrane

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24
Q

2 types of thirst

A

osmotic thirst and hypovalemic thirst

25
Q

osmotic thirst

A

stimulated by high extracellular solute concentration

26
Q

hypovalemic thirst

A

stimulated by low extracellular fluid volume

aka volumetric thirst

27
Q

baroreceptors

A

major blood vessels that detect any pressure drop from fluid loss

28
Q

osmosensory neurons

A

detect increased saltiness of extracellular fluid

29
Q

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

A

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

30
Q

what does the shrinkage of cells alter?

A

osmosensory neuron firing rate

31
Q

osmoreceptors

A

send signals to drink more water when cells shrink

detect and respond to changes in how much the membrane of the cell stretches

32
Q

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

A

osmosensory neurons

33
Q

lamina terminalis

A

anterior boundary of hypothalamus containing SFO and OVLT

34
Q

osmotic thirst =

A

OVLT

35
Q

circumventricular organs have fenestrated capillaries..

A

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

36
Q

OVLT neurons project to…

A

median preoptic area of the hypothalamus

37
Q

vasopressin produced in the _____ and stored in the _____

A

hypothalamus

posterior pituitary

38
Q

vasopressin associated with…

A

jealousy

water conservation - released when dehydrated

39
Q

when is vasopressin released?

A

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

40
Q

2 ways vasopressin conserves water

A

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

41
Q

Osmotic thirst: what happens when you eat something salty?

A
  • 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
42
Q

Osmotic thirst: what happens if drink too much water?

A
  • 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
43
Q

what is hypovolemic thirst triggered by?

A

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

44
Q

what monitors blood volume and induces volumetric thirst?

A

detector cells in heart and kidneys (stretch sensitive baroreceptors)

45
Q

what do kidneys produce in response to low volume?

A

angiotensin II

46
Q

angiotensin II

A

initiates drinking and salt appetite

induces eating and drinking

47
Q

what is the hormone signal for hypovolemic thirst?

A

angiotensin II

  • cannot cross BBB
  • acts in SFO to produce thirst
48
Q

SFO

A

circumventricular organ

49
Q

SFO neurons project to the ______ to _____

A

median preoptic nucleus of he hypothalamus

induce thirst

50
Q

neurons in SFO and OVLT send axons to…

A

part of the lamina terminalis

- the median preoptic nucleus

51
Q

median preoptic nucleus

A

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

52
Q

neural mechanism volumetric thirst

A
  • drop in fluid volumes causes release of angiotensin II which activates SFO neurons which send axons to median preoptic nucleus
53
Q

neural mechanism of osmotic thirst

A

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

54
Q

hypovolemic thirst path

A
  • dec blood volume
  • dec BP
  • inc angiotensin II
  • stimulates thirst center of hypothalamus
  • inc thirst from SFO
  • water taken in
    dec blood osmolality
55
Q

osmotic thirst path

A
  • 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
56
Q

How does your brain know when to stop drinking?

A

anterior cingulate cortex

57
Q

anterior cingulate cortex

A

shows strong activation during osmotic thirst

activation: immediately diminishes following drinking
- subjective thirst

58
Q

lamina terminalis

A

takes longer to decrease

- reflects biological thirst

59
Q

molecules in gut

A

determine how hydrated it will be

- alerts osmoreceptors when drink water in OVLT that inc in water, ACC shuts down

Neuroscience I (32 decks)

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