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Physiology Exam I > Action Potential > Flashcards

Action Potential Flashcards

1
Q

What happens during the Rising/Depolarization stage

A

Na+ channels open
Na+ rushes into cell
Makes cell membrane less negative

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2
Q

What happens during Overshoot stage

A

Na+ channels close
results in repolarization
makes cell membrane more negative

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3
Q

What happens during Falling stage

A

K+ channels open
K+ rushes out of cell
results in repolarization
makes cell membrane more negative

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4
Q

What happens in Undershoot stage

A

K+ channels close

hyperpolarization

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5
Q

Na+ channel resting state

A

Activation gate is close
Inactivation gate is open
Na+ can’t pass through channel

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6
Q

Na+ channel activation state

A

Activation gate is open
Inactivation gate is open
Na+ can pass through channel

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7
Q

Na+ channel inactivation state

A

Activation gate is open
Inactivation gate is closed
Na+ can’t pass through channel

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8
Q

Given the same membrane potential, which channel is MORE likely to open

A

Na+ channel

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9
Q

What is the K+ channel responsible for

A

repolarization

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10
Q

Threshold

A
  • enough depolarization to trigger an action potential

- inward flow of Na+ is greater than outward flow of K+

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11
Q

Factors that affect speed of action potential

A

axon diameter

myelination

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12
Q

Larger axon diameter results in

A

faster AP

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13
Q

Larger axon diameter results in

A

saltatory conduction which is faster

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14
Q

How does hypocalcemia affect threshold

A

increases chances of it being met

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15
Q

How does hypercalcemia affect thrershold

A

decreases chances of it being met

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16
Q

Symptoms of hypocalcemia

A

neuropsych
neuromuscular irritability
Chvostek’s sign
Trousseau’s sign

17
Q

Symptoms of hypercalcemia

A 
mental confusion
fatique
muscle weakness
diminished reflexes
coma
18
Q

Lowered Na+ ECM concentration has what affect

A

decreases chances of threshold bieng met

reduces peak amplitude

19
Q

MS

A

affects CNS
damages oligodendrites
causes demylination

20
Q

Guillan Barre

A

affects PNS
damages peripheral myline
causes demylination

21
Q

absolute refractory period

A

second action potential not possible during this period of time, regardless of strength

22
Q

Relative refractory period

A

second action potential possible, but it “costs” more

23
Q

How does local anesthesia work

A

LA blocks Na_ channels, inhibits action potential generation, reduces pain sensation

24
Q

Ouabain

A

causes Na/K pump to stop pumping. However the chem. conc. gradients take time to degrade and thousands of APs can go out

25
Q

What myelinates the PNS

A

Schwann Cells

26
Q

What myelinates the CNS

A

Oligodendrocytes

27
Q

Nodes of Ranvier

A

high density of Na+
AP only generated here
jump from one to the next

28
Q

what does TTX block

A

sodium channel

29
Q

Na+ channel properties

A

2 gates

3 states

30
Q

K+ channel properties

A

1 gate

2 states

31
Q

what is the undershoot/hyperpolarization phase due to

A

prolonged opening of voltage-gated K+ channels

32
Q

how does local anesthesia work

A

blocks Na+ channels, inhibits AP generation, reduces pain sensation

33
Q

chvoesterk’s sign

A

drunk test

34
Q

trouseeau’s sign

A

put a bp cuff on and cause muscle spasm in lower arm and hand

35
Q

what sign is more sensitive for hypocalcemia - trousseau’s or chvosterks

A

trouseeaus

36
Q

how does external Ca++ influence AP threshold

A

changing Na+ channel open probablity

37
Q

what happens if you stimulate an unmyelated axon in the middle

A

current flows in both directions

38
Q

where is density of Na+ channels super high

A

nodes of ranvier

39
Q

what is guillain-barre often preceded by

A

respiratory infection or stomach flu

Physiology Exam I (11 decks)

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