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L11, action potential part 1, physiology

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Mcq 

 1- Regarding voltage gated Na channels ,which is NOT true:
A- During rest, activation gates are closed
B-During early depolarization, activation gates open
C- During late depolarization, inactivation gates open
D- Complete closure of inactivation gate occur at late depolarization
2- Time between of application of stimulus and recording of action potential is called:
A- Stimulus artifact
B- Latent period
C- Spike
D- After potential
3- Which is true regarding ascending limb of action potential:
A- Represent Repolarization
B- Caused by Na outflow
C- Caused by K outflow
D- Represent depolarization
4- Regarding Firing level :
A- All Na channels are open
B- Membrane potential is 55 mv
C- Maximum rate of depolarization
D- All of the above
5- Repolarization phase, all are true         Except:
A- Occur due to K outflow
B- Represented by ascending limb
C- Start by inactivation of Na channels
D- Membrane potential change from +35 to near resting potential
6- Propagation of action potential in myelinated nerves occur via:
A- Local circuit mechanism
B- Saltatory mechanism
C- Very slow conduction
D- All of the above
7- Types of ion channels are:
A- Leak channels
B- Gated channels
C- All of the above
D- None of the above
8- All of the following are true about voltage gated Na channels except:
A- Have 2 gates , activation and inactivation gates
B- When membrane potential reaches +35 m.v. inactivation gates close completely
C- During early depolarization the activation gates are opened.
D- During rest ,the activation gates are opened 
9- Which is true about voltage gated k channels:
A- Have 2 gates , activation and inactivation gates
B- During rest the gate is closed
C- The gate becomes completely opened at the end of depolarization
 D- B and C
10- What are the phases of action potential:
A- Latent period
B- The spike
C- After potential
D- Stimulus artifact
E- All of the following
11- It indicates the time of application of the stimulus.
A- Latent period
B- Stimulus artifact
C- The spike
D- After potential
12- Latent period depends on :
A- Velocity of conduction of the nerve
B- The distance between the stimulus and the recording electrode
C- All of the above
D- None of the above 
13- The spike has amplitude of .....m.v.
A- 75
B- 90
C- 105
D- 120
14- Ascending limb :
A- Represents repolarization
B- It is due to K outflux
C- It is due to Na outflux
D- None of the above 
15- Descending limb:
A- It is due to Na influx and k efflux
B- It represents repolarization
C- During which the membrane potential change from +35 to near the resting state
D- All of the above 

16- What is the causes of after potentials :
A- It is due to slow outflow of the last 30% of k
B- Some voltage gated k channel close
C- Accumulation of large amount of k just outside the membrane
D- All of the above 
17- All of the following are true about Na-K pump except:
A- Primary active transport
B- Needs energy
C- Passive transport
D- Occurs against concentration gradient
18- The function of Na-K pump is:
A- Contributes for -14 m.v of RMP
B- Keeps high concentration of Na inside the cell
C- Controls cell volume
D- Keeps high concentration of K outside the cell

Answers of mcq


1)C

2)B

3)D

4) B 

5)B

6)B

7)C

8)D

9) B

10)E

11)B

12)C

13)C

14)D

15)D

16)D

17)C

18)C

True or false 

1- Action potential is the chemical changes which occur in RMP as a result of stimulation of nerve fiber by an effective stimulus

2- Action potential can be recorded by 2 microelectrodes both are placed on the outer surface of nerve fiber

3- Ascending limb of the spike represents repolarization

4- Conduction in unmyelinated nerve by local circuit mechanism

 5- Speed of conduction in myelinated nerve is rapid but in unmyelinated nerve is slow

Answers of  true or false

1- False
2- True
 3- False
4- True
 5- True 

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