Nerve Potential

Question 1

A rapid, spontaneous, large change in
membrane potential resulting in
depolarization followed by
repolarization of membrane”d

Answer 1

Action potential AP

Question 2

Brief reversal of membrane potential
occurs with a total amplitude of

Answer 2

100 mV

Question 3

What part of the nuerons is the voltage gated sodium or potassium gated channels present on ?

Answer 3

Axons

Question 4

——————is that level of membrane
potential [MP] at which action potential is
inevitable.

Answer 4

Threshold

Question 5

T/F: At threshold potential, net
inward current becomes larger than net
outward current

Answer 5

True

Question 6

What channels are working during resting state ?

Answer 6

Leaky potassium and na k pump

Question 7

During which stage does membrane potential move from -90 to 0 then +35

Answer 7

Depolarisation

Question 8

During which stage are both sodium gates open ?

Answer 8

Depolarisation

Question 9

T/F: after a brief delay DEPOLARISATION closes activation gates

Answer 9

False
Inactivation gates

Question 10

is the brief portion above the
zero level, when MP is positive

Answer 10

Overshoot (spike potential)

Question 11

When is membrane closest to Na+ equilibrium
potential

Answer 11

At the peak of AP

Question 12

What causes the downstroke in the graph ?

Answer 12

Potassium efflux

Question 13

When is the EP closest to potassium’s EP

Answer 13

During hyper-polarisation (undershoot)

Question 14

What restores the ELECTRICAL conditions of the membrane ?

Answer 14

Repolarisation via the voltage gated k channels

Question 15

What restores the ionic conditions ?

Answer 15

Sodium potassium pump

Question 16

Channels for graded potential ?

Answer 16

Ligand and mechanical

Question 17

The transmission of a depolarization process along a nerve fiber is called

Answer 17

Nerve impulse

Question 18

Neurons only fire APs when Vm is depolarized by

Answer 18

15 - 35 mV to reach Vth

Question 19

When membrane potential [Vm] is positive

Answer 19

Overshoot

Question 20

The part of AP following repolarization, where Vm is more negative

Answer 20

Undershoot or hyperpolarizing After potential

Question 21

AP fired at initial segment propagates to axon terminal at speeds of

Answer 21

0.25 -20 ms

Question 22

AP Speed of propagation [conduction velocity] depends on

Answer 22

Diameter and myelination
(Both Proportionally relative to speed)

Question 23

fast speed as impulse jumps on nodes of
Ranvier

Answer 23

Saltatory

Question 24

Where is ARP important

Answer 24

Cardiac muscle

Question 25

What event allows the return of normal excitability ?

Answer 25

Opening if inactivation gates

Question 26

Slide 19

Answer 26

:)

Question 27

Cause of muscle tetany?

Answer 27

Hypocalcemia

Question 28

a drug used in cardiac conditions like arrhythmias; blocks Na+ /K+ pump

Answer 28

Digitalis

Question 29

is an agent that
blocks V-G K+ channels and immediate repolarization.

Answer 29

Tetraethyl ammonium [TEA]

Question 30

is a naturally found poison that inactivates V-G Na+ channels; causes severe paralysis

Answer 30

Tetrodotoxin

Question 31

At threshold level there is explosive ↑ in Na+
permeability by

Answer 31

500-5000 times reaching +35

Question 32

At which value do inactivation gates close ?

Answer 32

30mv

Question 33

Total duration of AP

Answer 33

1 millisecond (0.001 s)

Question 34

Which of the following would increase the magnitude Of AP?
A)higher serum Na level
B)During relative refractory period C)abnormally high extracellular K+ level.
D)non

Answer 34

A