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Physiology > Lab 6 Action Potential > Flashcards

Lab 6 Action Potential Flashcards

1
Q

RMP and where is more negative?

A

-70, more negative on the inside

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2
Q

depolarization and cause

A
  • voltage is less negative, Na+ enters
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3
Q

hyperpolarization and cause

A

voltage is more negative, K+ keeps leaving or Cl- enters

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4
Q

stimulated neuron meaning

A

neuron where Na+ LGIC are open (EPSP generated)

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5
Q

EPSP cause and NT

A

Na+ LGIC open and Na+ enters causing depolarization, Ach on nicotinic and glutamat e

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6
Q

IPSP cause and NT

A

Cl- LGIC opens and Cl- enters causing hyperpolarization, GABA in brain and glycine in spine

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7
Q

4 phase of action potential and causes

A
  • EPSP/ graded potential caused by Na+ entering through LGIC
  • steep depolarization by Na+ entering through VGIC
  • steep repolarization by K+ leaving through K+ VGIC
  • after hyperpolarization by K+ still leaving
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8
Q

overall story of action potential generation

A

NT binds to Na+ LGIC opening it –> Na+ enters causing wave of depolarization going to axon hillock –> Na+ VGIC open causing depolarization and Na+ enters –> K+ VGIC open and K+ leaves causing repolarization –> K+ keeps leaving causing hyperpolarization –> Na+/K+ pump restores RMP

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9
Q

absolute refractory period

A
  • no AP possible

- all Na+ VGIC are inactive closed and must go back to active closed before they can open again

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10
Q

relative refractory period

A
  • AP possible if strong enough stimulation (more frequent or greater duration)
  • K+ hyerpolarization makes it hard for threshold to be reached
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11
Q

equilibrium potential meaning

A
  • if no other ion present around cell besides the one being examined and measure the voltage
  • balance of electrical and chemical gradient across cell
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12
Q

why RMP closer to equilibrium potential of K+

A

membrane more permeable to K+ due to leakage channels

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13
Q

equilibrium potential of K+ and Na+

A 
K+ = -90 = 
Na+ = +66
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14
Q

action potential vs graded potential

  • amplitude
  • max depolarization
  • summation
  • refractory period
  • initial stimulation
A
  • all or none vs graded
  • +40 vs 0
  • no summation vs yes summation
  • refractory period vs no refractory period
  • Na+ VGIC vs Na+ LGIC
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15
Q

summation meaning and temporal vs spatial summation

A
  • summation = graded potentials can add up or cancel each other out
  • temporal = higher frequency of graded potential
  • spatial = graded potential from multiple presynaptic neurons add up
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16
Q

2 ways intensity is encoded

A

1) increased frequency of AP

2) recruitment of more neurons to fire in a nerve

17
Q

all or none meaning and relation to different magnitudes of EPSP

A
  • AP happens or doesnt happen

- if EPSP too weak = no AP, if EPSP stronger AP generated, stronger EPSP generates same AP

18
Q

E, gNa, gK meaning

A 
E = membrane potential 
gNa = Na conductance / movement across membrane 
gK = K+ movement across membrane
19
Q

normal neuron at time 0

why gNa < gK

A

E = -63

gNa < gK because increased permeability to K+ due to leakage channels

20
Q

normal neuron at after hyper-polarization - what is the expected E value

A

E more negative then -63

21
Q

Na+ poison name and mechanism, common drug name

- effect on AP and why?

A

tetrodotoxin blocks Na+ VGIC

  • no AP because no depolarization can be created
  • lidocaine works the same way
22
Q

K+ channel poison

  • effect on AP and why
  • name of poison
A
  • cannot repolarize completely since K+ VGIC dont work
  • some repolarization due to leakage channel and Na+/K+ pumps
  • tetraehtyl ammonia
23
Q

hypernatremia

  • E at rest and why
  • overall magnitude of impact
A
  • more Na+ outside, slightly less negative RMP, very small impact in general
24
Q

hyponatremia

  • E at rest and why
  • affect on AP and why
A
  • less Na+ outside, RMP is slightly more negative

- weaker AP because less Na+ available to rush in

25
Q

mild hypoklemia

  • effect on E
  • effect on after hyperpolarization
A
  • less K+ outside, K+ leaves cell and RMP is more negative

- after hyperpolarization is more negative since steeper gradient for K+ to rush out

26
Q

mild hyperkalemia

  • effect on E
  • effect on gradient
  • effect on AP
  • relation to lethal injection
A
  • more K+ outside, K+ enters cell and makes RMP less negative
  • gradient is weaker
  • AP generate one after the other by one stimulus
  • K+ lethal injection causes seizures and cardiac arrhythmia
27
Q

severe hypo and hyper kalemia and why

A
  • both = no AP
  • hypo = less K+ in blood, K+ leaves causing hyperpolarzation of RMP that is so negative threshold can never be reached
  • hyper = more K+, inside of cell has lot of K+ so RMP less negative, Na+ VGIC open once then stay inactive (not sure why)
28
Q

second stimulus after relative refractory period

A

normal AP generated

29
Q

second stimulus during relative refractory period but is weak

A

no AP generated because stimulus is not strong enough small spike due to EPSP

30
Q

second stimulus during relative refractory period but is strong

A

AP generated but it is weaker due to K+ hyperpolarization

Physiology (25 decks)

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