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Question 1

What is action potential?

Answer 1

A change in resting membrane potential because of threshold stimulus

Question 2

Application of action potential

Answer 2

Stimulus artifact and latent period

Question 3

Stimulus artifact is….

Answer 3

Current leakage from stimulating to recording electrode

Question 4

Latent period is…..

Answer 4

• times that takes nerve impulse to travel
• indicates rate of conduction in axon

Question 5

Steps of action potential

Answer 5

Depolarization and repolarization

Question 6

Depolarization

Answer 6

• slow depolarization from -70 to -55 mV
  -firing level reach till 0 mV
  Then overshoot (reverse polarity) till +35 mV

Question 7

Cause of depolarization

Answer 7

Activation of voltage Na+ gates = excessive Na+ influx

Question 8

Repolarization

Answer 8

• return membrane potential to resting state

Question 9

What are the three steps of repolarization?

Answer 9

1. Rapid Repolarization
2. After depolarization (negative after potential)
3. After hypepolarization (positive after potential)

Question 10

Rapid repolarization

Answer 10

Restores 70% of resting condition

Question 11

Cause of rapid repolarization

Answer 11

Inactivation of Na+ gates
Activation of K+ gates

Question 12

After depolarization (negative after potential)

Answer 12

Rate of repolarization becomes slow

Question 13

Cause of after depolarization (negative after potential)

Answer 13

Decrease in K+ gradient …… slow K+ efflux …… delayed repolarization

Question 14

After hyperpolarization (positive after potential)

Answer 14

Reaching RMP by overshoot of hyperpolarized then return to normal

Question 15

Cause of after hyperpolarization (positive after potential)

Answer 15

Delay of K+ channels closure …… more K+ efflux …… more hyperpolarization

Question 16

Properties of action potential

Answer 16

1. Threshold stimulus
2. Propagation in both direction
3. Obeys all or none law
4. Constant duration
5. Ionic changes