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Flashcards in Lecture 3 Deck (50)
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1

myelinated fiber

enclosed in a sheath made of nonneural cells (glial cells)

2

The ____________ has breaks (Ranvier nodes) where action potentials are generated

myelin sheath

3

Slow nerve conduction speed

0.5 m/s

4

Sprinter Speed

10.0 m/s

5

Speed Limit

30 m/s

6

Fast nerve conduction speed

100 m/s

7

Sound in air speed

330.0 m/s

8

Light or electromagnetic field

300,000,000 m/s

9

Conduction of an Action Potential

1. Membrane depolarization to the threshold
2. Generation of an action potential
3. Local currents spread passively
4. They depolarize adjacent areas of the membrane
5. A new action potential is generated

10

Myelin increase what in local currents?

Myelin increases the effective distance of local currents

11

What is the velocity of conduction in myelinated fibers?

6*d (m)

velocity in m/s

12

Orthodomic Conduction

from soma to terminal branches

13

Anti-orthodomic conduction

from the end of the axon to the soma

14

Soma

body of the cell; the site of input signals

15

Dendrites

shot branches originating from the soma; sites of inputs

16

Axon

a long branch; transmits output signals

17

Axon Hillock

the site where the axon exits the soma; typically, the site of generation of action potentials

18

terminal branches

a "brush" at the end of the axon

19

myelin

a fatlike substance covering the axon; it increases the speed of conduction of action potentials

20

ranvier nodes

breaks in the myelin sheath; places where action potentials are generated

21

Nerve (peripheral) or neural tract (central)

many axons running together

22

How many ion channels are there under the myelin sheath in a neuron?

there are virtually no ion channels under the myelin sheath.

23

How many ion channels are there in the Ranvier nodes in neurons?

There are many ion channels in the Ranvier nodes.

24

the importance of ______ for the generation of APs has gained prominence lately (steady depolarization) in neurons.

dendrites

25

What is a PIC?

a depolarizing inward current that activates as long as the membrane potential is depolarized

26

PIC's allow for an increase _________________.

in the number of action potentials that are generated.

27

Recent studies have reported that PIC's are strong in ____________ during everyday tasks.

human alpha motorneurons

28

PIC's are likely strong enough to play a major role in defininf the patterns of ________________________.

recruitment and derecruitment of motor units

29

PIC's are very sensitive to ___________ inhibition, meaning they can be controlled?

postsynaptic

30

What effect does the all or none law have on action potential generation?

Each action potential transmits 1 bit of information