2.6 Lundy Ch. 2 (3) Flashcards Preview

7303 Neuroanatomy > 2.6 Lundy Ch. 2 (3) > Flashcards

Flashcards in 2.6 Lundy Ch. 2 (3) Deck (21)
Loading flashcards...
1
Q

How is the meaning of an action potential determined?

A

by the neural pathway in which it is conducted, not the signal itself

2
Q

all-or-none

A
  • minimally sufficient stimuli trigger

- stronger stimuli don’t change signal

3
Q

trigger zone/axon hillock

A

region in neurons with a high concentration of Na+ channels

4
Q

AP generation involves a sudden influx of this into the cell

A

Na+

through Na+ channels in axon hillock

5
Q

How do local potentials produce an action potential?

A
  • summated membrane depolarization beyond threshold

- causes Na+ channels to open

6
Q

What is the threshold membrane potential to develop an AP?

A

-55 mV

7
Q

depolarization and repolarization in action potential

A

1: -55 mV » Na+ channels open
2: Na+ flows in and depolarizes
3: K+ channels open and get rapid repolarization

8
Q

Why is there hyperpolarization?

A

K+ flowing out

9
Q

refractory period

A
  • membrane is hyperpolarized

- difficult to regenerate action potential

10
Q

absolute refractory period

A

membrane unresponsive to stimuli

11
Q

relative refractory period

A
  • stimulus may activate

- must be stronger than normal to activate an AP

12
Q

purpose of refractory period

A
  • promotes forward propagation

- prevents backflow

13
Q

What restores the membrane to normal RMP from hyperpolarization?

A

Na/K pump

14
Q

contributing factors to faster AP propagation

A
  • increased diameter of axon

- myelination

15
Q

benefit of insulation through myelination

A

prevents current flow across axonal membrane

16
Q

Without insulation, the amplitude of the potential would

A

dissipate down the axon

17
Q

nodes of Ranvier allow

A

ion flow across the membrane

18
Q

nodes have high densities of

A

Na+ and K+ channels

19
Q

What causes regeneration of the AP?

A

depolarization at the nodes of Ranvier

20
Q

saltatory conduction

A

AP seems to jump from node to node

21
Q

AP maintains this due to saltatory conduction

A
  • size

- shape