S2_L2: Action Potential and Conduction of Impulses

Question 1

Determine the corresponding descriptions of the types of conduction of impulses

1. Example is: Cell body to synapse
2. from site of stimulation to the nerve cell body
3. Example is: Middle of axon to the synapse
4. from site of stimulation to the synaptic terminals

A. Orthodromic
B. Antidromic

Answer 1

1. A
2. B
3. A
4. A

Question 2

Phenomenon where the impulse jumps from one node of Ranvier to another; myelin is an insulator so the impulse jumps

Answer 2

Saltatory conduction

Question 3

Resting membrane potential of a nerve

Answer 3

-70 mV

Question 4

Period where there is no stimulation and lets it return into the resting membrane potential

Answer 4

Latent period

Question 5

Once a nerve is stimulated and an electrical impulse is given, the overshoot (total repolarization) occurs after reaching ___ mV.

Answer 5

-55

Question 6

Occurs at +40 mV where the nerve is dead because there are no more ionic gradients and the plasma membrane failed to maintain the ionic gradients

Answer 6

Sodium equilibrium potential

Question 7

A local non-propagated potential. It is a disturbance in the membrane potential.

Answer 7

Electrotonic potential

Question 8

Law that states a threshold potential (15mV and above) will produce an action potential
of the same height all throughout.

Answer 8

All or none law

Question 9

A subthreshold potential will cause a ___

Answer 9

generator potential

Question 10

If a nerve is stimulated with ___ mV, the threshold potential is reached and a full-pledged action potential occurs. All voltage-gated channels will open.

Answer 10

15

Question 11

The absolute refractory period is described when the nerve cannot be stimulated for the 2nd time within the period. It starts from firing level to about ___.

Answer 11

1/3 of repolarization

Question 12

The ___ is a period where an action potential may or may not be produced, it will depend on the magnitude of the potential given. This occurs after 1/3 of repolarization.

Answer 12

relative refractory period

Question 13

If the sodium inactivation gate is closed, the channel is in the ___ state.

Answer 13

inactivated

Question 14

The sodium activation gate is found (1)___, while the sodium inactivation gate is found (2)___.

Answer 14

1. extracellularly
2. intracellularly

Question 15

At rest, which sodium gate is closed and which is open?

Answer 15

Closed: Activation gate
Open: Inactivation gate

Question 16

TRUE OR FALSE: During depolarization, no K+ ions exit yet because the K+ channel
is a slow-opening channel.

Answer 16

True

Question 17

During the peak of the graph, the sodium ___ gate closes. Sodium cannot enter anymore
and diffusion of sodium stops.

Answer 17

Inactivation

Question 18

TRUE OR FALSE: As K+ channels are slowly closing, this causes hyperpolarization because potassium continues to exit

Answer 18

True

Question 19

Fiber type most susceptible to hypoxia
A. A fibers
B. B fibers
C. C fibers

Answer 19

B. B fibers

Autonomic nervous system fibers that cannot compensate for their sickness

Question 20

Fiber type most susceptible to pressure
A. A fibers
B. B fibers
C. C fibers

Answer 20

A. A fibers

Question 21

Fiber type most susceptible to local anesthetics
A. A fibers
B. B fibers
C. C fibers

Answer 21

C. C fibers