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

Physiology Quiz 2 (2/2) Flashcards

0
Q

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

A

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

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1
Q

Resting potential (mV)

A

65 mV

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2
Q

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

A

Concentration and electrical gradient favor inward flow

-passively diffuses

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3
Q

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

A

Negative

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4
Q

Repolarization is due to

A

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

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5
Q

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

A

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

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6
Q

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

A

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

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7
Q

Excitability/irritability

A

Possessing the ability to produce an action potential

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8
Q

Stimulus

A

Event or process which elicits a depolarization

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9
Q

Threshold stimulus

A

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

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10
Q

Subthreshold stimulus

A

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

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11
Q

All-or-none phenomenon

A

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)

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12
Q

Temporal summation

A

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

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13
Q

Spatial summation

A

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

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14
Q

Electronic or decremental conduction

A

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

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15
Q

Absolute refractory period

A

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

16
Q

Relative refractory period

A

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

17
Q

Voltage dependent

A

Membrane depends of voltage becoming more negative to reset

18
Q

Time dependent

A

Takes time for membrane to repolarize

19
Q

Accommodation

A

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
Q

Tetrodotoxin (TTX)

A

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
Q

Tetraethylammonium (TEA)

A

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
Q

Myelin

A

Fatty sheath that covers nerve cell to insulate it

23
Q

How I myelinated action potentials travel

A

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

24
Q

Types of stimuli

A

Chemical
Electrical
Mechanical

25
Q

How myelinated fibers transmit

A

Saltatory conduction

26
Q

Saltatory conduction

A

Skipping from node to node

27
Q

Alpha motor neurons

A

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

28
Q

How myelin affects size of cells

A

Allows nerve trunks to be smaller and still conduct quickly

29
Q

How myelin influences energy conservation

A

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
Q

How Myles influences rapid repetitive firing

A

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

31
Q

How myelin insulates

A

Lipid material= strong insulating properties; prevents cross reactions

32
Q

How MS relates to myelin

A

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

Physiology (17 decks)

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