Bmsc 207: Final Review Updated Actual Questions And Correct Answers

BMSC 207: FINAL REVIEW UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS

Question:
1. What neuron is NOT a apart of the efferent pathway?
Answer:
Sensory

Question:
2. The sympathetic and parasympathetic nervous system are divisions of what system?
Answer:
The autonomic nervous system

Question:
3. Which glial cells from myelin in the central nervous system?
Answer:
Oligodendrocytes

Question:
4. What is a difference between the synaptic cleft and the synapse?
Answer:
The synaptic cleft is the space between a presynaptic axon terminal and the postsynaptic dendrite, and a
synapse includes all three of these structures.

Question:
5. The neurons of the central nervous system are also known as
Answer:
interneurons

Question:
6. Where in the neuron is an action potential initially generated?
Answer:
Axon Hillock

Question:
7. The depolarization phase of an action potential results from the opening of which channels?
Answer:
voltage gated Na+ channels

Question:
8. The repolarization phase of an action potential results from?
Answer:
The opening of voltage gated K+ channels

,Question:
9. Hyperpolarization results from?
Answer:
slow closing of voltage-gated K+ channels

Question:
10. What is the magnitude (amplitude) of an action potential?
Answer:
100mV

Question:
11. How is an action potential propagated along an axon?
Answer:
An influx of sodium ions from the current action potential depolarizes the adjacent area.

Question:
12. Why does the action potential only move away from the cell body?
Answer:
The areas that have had the action potential are refractory to a new action potential.

Question:
13. The velocity of the action potential is fastest in which of the following axons?
Answer:
a small myelinated axon

Question:
14. What opens first in response to a threshold stimulus?
Answer:
Voltage-gated Na+ channels

Question:
15. What characterizes depolarization, the first phase of the action potential?
Answer:
The membrane potential changes from a negative value to a positive value. Submit

Question:
16. What characterizes repolarization, the second phase of the action potential?
Answer:
Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of
-70 mV.

Question:
17. What event triggers the generation of an action potential?
Answer:
The membrane potential must depolarize from the resting voltage of
-70 mV to a threshold value of -55 mV.

, Question:
18. What is the first change to occur in response to a threshold stimulus?
Answer:
Voltage-gated Na+ channels change shape, and their activation gates open.

Question:
19. What type of conduction takes place in unmyelinated axons?
Answer:
Continuous conduction

Question:
20. An action potential is self-regenerating because __________.
Answer:
depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential
at the next segment

Question:
21. Why does regeneration of the action potential occur in one direction, rather than in two directions?
Answer:
The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an
action potential.

Question:
22. What is the function of the myelin sheath?
Answer:
The myelin sheath increases the speed of action potential conduction from the initial segment to the axon
terminals.

Question:
23. What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization?
Answer:
Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+
channels open.

Question:
24. In which type of axon will velocity of action potential conduction be the fastest?
Answer:
Myelinated axons with the largest diameter

Question:
25. During an action potential, the rapid decrease in sodium ion permeability and the simultaneous and
rapid increase in potassium ion permeability is responsible for __________.
Answer:
the repolarization phase

Question:
26. During an action potential, when does sodium ion permeability begin to significantly decline?