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BECOM Exam 2 > Action Potential > Flashcards

Action Potential Flashcards

1
Q

Where is a graded potential located?

A

dendrites or cell bodies

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2
Q

Where is an action potential located?

A

Trigger zone (axon hillock)&raquo_space; Axon

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3
Q

What type of ion channels are involved with a graded potential?

A

any type

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4
Q

What type of ion channels are involved with an action potential?

A

Voltage only (Na+, K+ only)

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5
Q

What type of signal is a graded potential?

A

Depolarizing or hyperpolarizing

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6
Q

What type of signal is an action potential?

A

Depolarizing only

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7
Q

What is the strength of a graded potential?

A

Depends, summation possible

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8
Q

What is the strength of an action potential?

A

Always the same

Cannot be summed

Refractory period obeyed

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9
Q

How is a graded potential initiated?

A

Ions through channel

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10
Q

How is an action potential initiated?

A

Above threshold graded potential at the axon hillock

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11
Q

What is an action potential?

A

A regenerating depolarization of membrane potential that propagates along an excitable membrane

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12
Q

Key features of an action potential

A
  • All-or-none event
  • Need to reach threshold
  • Have constant amplitude
  • Do not summate
  • Initiated by depolarization
  • Involve changes in permeability
  • Rely on voltage-gated ion channels
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13
Q

3 Functions of Action Potentials

A
  • Information delivery to CNS
  • Information encoding
  • Rapid transmission over distance (nerve cell APs)
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14
Q

What do local anesthetics do to action potentials?

A

Block APs in nerve cells

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15
Q

What happens after a local anesthetic is used?

A

Produces analgesia without paralysis

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16
Q

Why do local anesthetics work?

A

They are more effective against a small diameter

Large Surface Area:Volume ratio

C-fibers more than a-motor neurons

17
Q

Can amplitude change for APs?

A

No

18
Q

What does the speed of transmission depend on?

A

fiber size and whether it is myelinated or not

19
Q

What does the AP do to non-nervous tissues?

A

Initiates a range of cellular responses

Ex:
Muscle contraction
Secretion

20
Q

What are the steps of an AP?

A

1- Resting membrane potential
2- Depolarizing stimulus
3- Membrane depolarizes to threshold. VG-Na+ channels open. Na+ enters cell. VG-K+ channels open slowly.
4- Rapid Na+ entry depolarizes cell
5- Na+ channels close, Slow K+ channels open
6- K+ moves out from cell to ECF
7- K+ remains open, additional K+ leaves cell. Hyperpolarization
8- VG-K+ channels close, less K+ leaks out of cell
9- Cell returns to resting ion permeability and RMP

BECOM Exam 2 (9 decks)

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