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Neuro I > Generation & Propagation of Action Potentials > Flashcards

Generation & Propagation of Action Potentials Flashcards

1
Q

What acts as a capacitor in the cell?

Where are the - charges?

A

Cell membranes

Negative charges on the intracellular ide

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2
Q

What effect does capacitance have on action potential?

A

Slows the time course because capacitance must first be disipated for depolarization & hyperpolarization.
Rapid

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3
Q

Membrane Time Constant

A

Time it takes for a 63% change in membrane potential

1-10 milliseconds

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4
Q

Temporal summation and effect of time constant

A

Longer time constant = action potentials can overlap

Also refers to small stimuli that can only generate an AP if fired closely after each other

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5
Q

Speed of propagation

A

1/sqrt((rmXri) X Cm)

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6
Q

Length Constant

A

sqrt(rm/ri)

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7
Q

Name 4 passive membrane properties

A
  1. Capacitance
  2. Membrane time constant
  3. Speed of propagation
  4. Length constant
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8
Q

Name 1 organism that relies solely on passive properties for membrane AP

A

C. elegans

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9
Q

Absolute refractory period

A

No AP can be generated

Na channels open & become inactivated

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10
Q

Refractory period

A

Greater stimulus required to generate an AP

K + channels open but overshoot hyperpolization

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11
Q

Role of pore loops

A

Ion selectivity based on size + hyrdophobicity

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12
Q

Role of S4 membrane

A

Every 3rd amino acid + charged

AP results in confirmation change, twists ad moves up, opens channel

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13
Q

K channel inactivation method

A

Ball and chain

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14
Q

Na channel inactivation method

A

Loop between 3rd and 4th domains stays “plugged in” until membrane is repolarized

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15
Q

Rank activation speed

NA K Ca

A
  1. Na
  2. Ca
  3. K
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16
Q

Rank Inactivation speed

Na and Ca

A

Na faster than Ca

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17
Q

Role of CA on AP

A

Depolaization

18
Q

Role of K on AP

A

Repolarization

Delays reaching threshhol

19
Q

Role of Ca on AP

A

Delays repolirization

Sometimes see Ca shoulder

20
Q

What are “A current” channels

A

Special K channels that prolong the interspike interval

21
Q

What are Nucleotide gated channels

A
  • Important in pacemaker cells
  • Open only in hyperpolarized state
  • Encourage depolarization towards threshold
  • Cation influx
22
Q

Name 3 Na channel blockers

A

Tetrodotoxin
Saxitoxin
Lidocaine

23
Q

Name 1 K channel blocker

A

Tetrathyamonium (TEA)

24
Q

Name 1 Ca channel blocker

A

Conus toxin

25
Q

What channel is overactive in pain

A

Na

26
Q

What channels are responsible for hyperactivity in epilepsy

A

Na

- Fail to inactivate, prolonged deolarization, abnormal excitability

27
Q

Define channelopathies

A

Genetic disorders in channel functioning

28
Q

Dysmylinating vs Demylinating disease

A 
Dys = abnormal myelin
De = No myelin
29
Q

Gullian Barre Syndrome

A

PNS myelin is lost

30
Q

Multiple sclerosis

A

CNS myelin is lost

31
Q

Charcot-Mari-Toot Syndrome

A

Gap junctions are abnormal, no nutrient transfer to outer layers = death

32
Q

Proagation is usally uni-directional but what channels can cuse bidirectional propagation?

A

Na

33
Q 
Effect of diametr on the following
Capaciatance
Membrane Resistance
Speed
Internal resistance
A

Inc. capacitance
Dec. membrane resistance
Inc. speed
Dec. internal resistance (inverse square of diameter)

34
Q

Benefits of mylination

A

Less ATP
Decrease capacitance
Increases speed, length constant, membrane resistance

35
Q

Support neurons of PNS

A

Schawn cells

36
Q

Support neurons of the CNS

A

Glial cells

37
Q

What cells interact in order to trigger myelination

A

Glia and axons

38
Q

What molecule determines the number of “wraps” of myelin

A

neuroglin

39
Q

Role of Myelin Associated Protein in myelination

PNS or CNS

A

Initial glial-axon interaction

PNS & CNS

40
Q

Po

PNS or CNS

A

Myelin compaction

PNS

41
Q

Proteolipid Protein

PNS or CNS

A

Mylin compaction

CNS

42
Q

Myelin Basic Protein

PNS or CNS

A

Myelin compaction

CNS & PNS

Neuro I (10 decks)

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