Neuro Midterm 2009
1. Regarding the graph above, which of the following line(s) represents a non-voltage depndant gatting
channel?
a. A
b. B
c. C
d. A+B
e C+A
2. Regarding the graph above, which of the following lines(s) represents a voltage dependant getting
channel?
a. A
b. B
c. C
d. A+B
e C+A
3. Which of the following is/are true regarding the ion channel that “curve b” in the graph represents?
a. made up of a single polypeptide with four homologous domains
b. each domain consists of 6 membrane spanning alpha helices
c. the s4 helix is not voltage sensing
d. A+B
e. All of the above
4. A newly discovered ion, Aw3+, has an extracellular concentration of 2 mM and an intracellular
concentration of ___. What is the Nernst Potential of Aw3+, given that the value of RT/F is 62?
a.
b.
c.
d. e.
5. The Na+ K+ AtPase is extremely important for maintaining the resting membrane potential. Which of
the following is false regarding the transporter?
a. The Na+K+ ATPase transports 3 Na+ ions out of the cell and 2K+ ions into the cell
b. The Na+K+ ATPase produces ATP while it transports ions down its concentration gradient
c. The Na+K+ ATPase transports 2 Na+ ions out of the cell and 3K+ ions into the cell
d. A+B
e. B+C
6. Which of the following is true regarding the Patch clamp?
a. Uses only a single electrode to measure current
b. Uses multiple electrodes to measure current
c. The solution in the micropipette is hypotonic to the bathing solution
d. A+C
e. All are correct
7. Which of the following is true about passive facilitated diffusion?
a. Passive facilitated diffusion moves molecules against the concentration gradient
b. Passive facilitated diffusion requires ATP to function
c. Passive facilitated diffusion has a negative Gibbs free energy
d. Passive facilitated diffusion decreases entropy
e. All of the above
8. Which of the following are incorrect reasons for why the initiation of action potentials (AP) begins at the
axon hillock?
a. Lower threshold for AP initiation
b. Smaller diameter
c. High density of K+ channels in the initial segment of the axon then in the ___ of the dendrites
d. A+C
e. All are correct
9. The refractory period in an action potential is caused by …?
a. Inactivation of the voltage gated potassium channels
b. Inactivation of the voltage gated sodium channels
c. The fast opening sodium channels
d. A+B
e. A+B+C
10. Which of the following is correct regarding the resting membrane potential?
a. potassium channels are always open
b. the permeability of potassium channels is greater then the permeability of sodium channels
c. the resting membrane potential is closer to __
d. the resting membrane potential is closer to __
e.A+B+C
f. A+B+D
11. Which of the following is correct regarding the absolute refractory period during an action potential?
a. The voltage-gated sodium channels are inactivated
b. The voltage-gated potassium channels are inactivated
c. A stronger then normal stimulus is recorded to elicit a second action potential
d. A second stimulus, no matte how strong, will not elicit a second action potential
e. A+D
f. A+C
17. A voltage clamp measures:
(a) sensitivity of the membrane voltage to sodium/potassium ATPase current
(b) sensitivity of the membrane voltage to the potassium concentration
(c) sensitivity of the membrane voltage to the sodium and potassium current
(d) change in the membrane conductivity as a function of the membrane
voltage
18. As the conductance of the membrane to a give ion becomes smaller:
(a) the membrane potential approaches the Goldman potential of that given ion
(b) the membrane potential is less sensitive to the Nernst potential of that
given ion
(c) the membrane potential depolarizes
(d) the membrane potential hyperpolarizes
24. Membrane refractoriness is
A. Process of recovering from previous AP
B. Process of recovering from previous synaptic neurotransmitter release
C. Time that passes from the peak to the min membrame voltage in a single AP
D. The time it takes from the na channel to move from the inactive to closed states
25. The I-V relations of a non pace making cell .... (graph)
which curve shown in figure shows results?
A. A or B
B. B or C
C. C or D
D. A or D
28. Electrical Synapses are:
a. transmembrane proteins that conduct current through their pore
b. channels that are able to conduct current symmetrically from both direction
c. channels that conduct current according to the electrochemical gradient of the
anions and cations
d. all of the above is true
29. What is the crucial factor that determines the decay of the synaptic current at
the neuromascular junction under normal conditions?
a. the diffusion of acetyl choline from the synaptic cleft
b. the clearance of acetyl choline by acetylcholinesterase
c. the channel open time of the acetyl choline channel
d. the transport of acetyl chloline into the presynaptic terminal.
30. In contrast to the Neuromuscular Junction in the CNS, nervous activation of a
single axon cannot drive a neuron to fire action potentials. The reason for this is:
A. The threshold for action potential generation in the CNS neurons is much
higher compared to Neuromuscular Junction synapses.
B. A single synapse generates small voltage at the soma because it releases
only a few vesicles following stimulation.
C. CNS neurons are more “leaky” compared to Neuromuscular Junction
neurons, thus a single synapse cannot depolarize effectively a CNS neuron.
D. The reversal potentials of neurotransmitters at the CNS are much lower
compared to the Neuromuscular Junction.