Physiology Quiz 2 (2/2) Flashcards Preview

Physiology > Physiology Quiz 2 (2/2) > Flashcards

Flashcards in Physiology Quiz 2 (2/2) Deck (33):
0

Resting potential (mV)

65 mV

1

In depolarization, does the membrane charge change in a positive or negative direction?

Positive-due to large increase in sodium conductance g=3 or 4

2

During depolarization with increase in Na conductance, which direction will Na flow?

Concentration and electrical gradient favor inward flow
-passively diffuses

3

Does membrane charge change in a positive or negative direction during repolarization?

Negative

4

Repolarization is due to

Sudden large increase in K conductance (overall outward flux)
Sodium-potassium pump

5

What will happen to K when its conductance suddenly increases dramatically?

Overall outward flux due to concentration and electrical gradient
-passive diffusion

6

Wy does sodium-potassium pump only have influence during repolarization?

It is always running but it is simply overwhelmed during depolarization because of the large amount of Na rushing in

7

Excitability/irritability

Possessing the ability to produce an action potential

8

Stimulus

Event or process which elicits a depolarization

9

Threshold stimulus

A stimulus strong enough to elicit a depolarization that is an action potential.

10

Subthreshold stimulus

A stimulus that causes a depolarization, but not an action potential

11

All-or-none phenomenon

Once a threshold stimulus occurs and if there are no abnormalities in the nerve cell, the action potential will always look the same for that single nerve cell (resting charge and peak will always be the same)

12

Temporal summation

Two or more stimuli occur close in time so that they are able to add their effects

13

Spatial summation

Two or more stimuli that occur close in proximity so that they are able to add their effects

14

Electronic or decremental conduction

An impulse travels through a nerve membrane without self propagation and gradually dies out over distance due to the resistance of the membrane to electrical current; applies to subthreashold stimuli only

15

Absolute refractory period

The time during an action potential when it is impossible to cause another action potential, no matter how strong the stimulus is

16

Relative refractory period

The time during an action potential when it is possible to cause another action potential, however you need a stimulus stronger than usual

17

Voltage dependent

Membrane depends of voltage becoming more negative to reset

18

Time dependent

Takes time for membrane to repolarize

19

Accommodation

Situation where several subthreashold stimuli arrive at a nerve fiber but are separated enough by time or distance that they cannot sum enough to reach threshold; results in cell or fiber becoming less ale to fire due to Na channels being in refractory periods and not all reset and available to fire

20

Tetrodotoxin (TTX)

Toxin found in puffer fish which blocks Na channels of nerves; dos not allow nerves to fire (usually respiratory nerves are blocked and victim stops breathing)

21

Tetraethylammonium (TEA)

Blocks K channels; no/super slow repolarization because K channels will not allow K to flow back out; only sodium-potassium channel will be at work

22

Myelin

Fatty sheath that covers nerve cell to insulate it

23

How I myelinated action potentials travel

Self propagation; velocity of impulse is proportional to the diameter of the cell (^diameter, ^velocity)

24

Types of stimuli

Chemical
Electrical
Mechanical

25

How myelinated fibers transmit

Saltatory conduction

26

Saltatory conduction

Skipping from node to node

27

Alpha motor neurons

Largest, fastest, myelinated fibers. Usually found in skeletal muscle and reflex loops

28

How myelin affects size of cells

Allows nerve trunks to be smaller and still conduct quickly

29

How myelin influences energy conservation

Don't lose as much energy while nerve conducts
-less Na needed for depolarization--> less Na to expell using sodium-potassium pump--> less ATP needed for pump

30

How Myles influences rapid repetitive firing

Less Na to remove from cell= quicker repolarization= quicker ability to fire again

31

How myelin insulates

Lipid material= strong insulating properties; prevents cross reactions

32

How MS relates to myelin

Motor control issues due to loss of myelination causing neurons to cross-react