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neuro > 2 Action Potentials > Flashcards

2 Action Potentials Flashcards

1
Q

capacitance

A

whenever two conducting materials are separated by an insulating membrane

passive membrane properties

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2
Q

capacitance is ___ proportional to thickness of a capacitor

A

inversely

passive membrane properties

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3
Q

current

A

the net movement of electrical charge

passive membrane properties

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4
Q

capacitive current

A

before ions flowing across a cell membrane can cause a change a change in voltage, they need to strip ions away from the inner cell membrane

passive membrane properties

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5
Q

capacitive current (stimulates/ inhbits) action potentials

A

inhibits: it represents a charge sink that must be “filled” before there is a net flow of ions across the membrane

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6
Q

membrane time constant (tau)

A

time it takes for 63% of a total membrane potential to change

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7
Q

temporal summation

A

favored by a longer time constant or more frequent stimuli

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8
Q

cable properties

A

consider the axon a series of membrane segments, each with its own membrane resistance and membrane capacitance to current flow into the cytoplasm

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9
Q

length constant

A

the distance at which 37% of the original change in membrane potential still occurs

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10
Q

speed of propagation

A

large diameter axons are faster

passive membrane properties

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11
Q

Ri

A

internal resistance, 1/diameter squared)

passive membrane properties

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12
Q

Rm

A

1/ Diameter

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13
Q

Gullian-Barre Syndrome

A

loss of myelin in PNS only

diseases

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14
Q

Multiple Sclerosis

A

loss of myelin in CNS only: T cell immune infiltrates cause activation of microglia and macrophages

diseases

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15
Q

Charcot-Marie-Tooth Disease

A

a peripheraland sensory neuropathy caused by loss of myelin due to gap junction mutation

demyelinating disease

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16
Q

tetrodioxin (TTX)

A

puffer fish toxin, blocks Na+ channel

Toxin: Na+ Channel

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17
Q

Saxitoxin (STX)

A

red algae toxin; plugs Na+ channels

Toxin: Na+ Channel

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18
Q

Conus Toxin

A

blocks Calcium gated channels

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19
Q

myelin plaque

A

the accumulation of debris, microglia, and macrophages at the focal sites of myelin destruction

Diseases

20
Q

axon diameter- speed?

A
  1. largest: golgia tendon bodies
  2. mechanoreceptors of skin
  3. pain, temperature
  4. smallest temperature, itch, pain

myelin

21
Q

what percent of Schwann cells form a sheath around a single axon?

A

30%, most form loops around multiple axons

22
Q

Neuregulin (NRG)

A

regulates the thickness of the myelin sheath (number of layers)

23
Q

channelopathies

A

diseases caused by mutations in channels, often associated with epilepsy

24
Q

lidocaine

A

binds to Na+ and promotes inactivation

25
Q

rising phase

A

voltage-gated Na+ channels open, K+ activation is slow

26
Q

falling phase

A

Na channel inactivation and K channel activation

dominate

27
Q

absolute refractory period

A

too much Na+ inactivation

28
Q

relative refractory period

A

residual K+ activity still occuring and counteracting depolarization

29
Q

3 common parts of a voltage-gated ion channel

A
  1. pore loop (P)
  2. Voltage sensor (S4 region)
  3. inactivation loop
30
Q

selectivity filter

A
  1. ion size

2. hydration energy

31
Q

pore loops

A

ion selectivity, charges at the tip of the loop can significantly alter the ion that is selected for

32
Q

S4 Region

A

voltage sensitivity, an OUTWARD TWIST due to positive charges repeating every 3 amino acids respond to changes in membrane potential

33
Q

K+ inactivation

A

ball and chain model

ball: positive charge
chain: flexible AAs

34
Q

sodium channel inactivation

A

a plug between domains 3 and 4

35
Q

Ca Channels: T-type

A

located at the end of synapses

36
Q

Ca Channels: L-type

A

the cell body of neurons

37
Q

which channels activate fastest: Na, K, Ca

A

Na> Ca> K
Fast>Medium> Slow

inactivation is slower than Na

38
Q

Ca shoulder

A

Ca delays the repolarization of the membrane

an epinephrine-enhanced

39
Q

norepinephrine effec ton Ca2+

A

NE can inhibit Ca influx in the Pre-Synaptic neurons via Beta/ Gamma units

40
Q

delayed rectified K channels

A

do not inactviate, rather remain open as long as the membrane is depolarized

41
Q

role: TASK K channel

A

resting membrane potential

42
Q

Voltage-Gated Na Channels

A

action potentials

43
Q

Voltage-Gated K Channels

A

delayed rectified, non-inactivating

action potentials

44
Q

Voltage Gated Ca channels

A

action potentials, neurotransmitter release

45
Q

Voltage Gated K Channels, A current, rapidly inactivating

A

firing rate

46
Q

Hyperpolarizing-activated cation channels

A

Ih, HCN channels

firing rates, pacemaking, rhythmic activity

neuro (10 decks)

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