1a. Which of the following best describes what is meant by two-motor-neuron path

Question

1a. Which of the following best describes what is meant by two-motor-neuron pathway?

A.Afferent information travels toward the CNS along two neurons connected in sequence

B.Integrative function in the CNS requires two neurons

C.Nerve impulses travel from the CNS to the effector along two neurons connected in sequence

D.Sympathetic and parasympathetic nerve impulses travel along two neurons that are not connected but run parallel to each other

E.Motor nerve impulses travel along two separate neurons such that they reach two different effectors simultaneously

1b.The membrane potential (mV) of several neurons was measured at three points in time during a nerve impulse: Time 1, Time 2, and Time 3. Which neuron exhibited a subthreshold, depolarizing graded potential?

A.Neuron A: Time 1 = -70mV Time 2 = +30mV Time 3 = -90mV

B.Neuron B: Time 1 = -70mV Time 2 = -65mV Time 3 = -70mV C.Neuron

C: Time 1 = -70mV Time 2 = -85mV Time 3 = -70mV

D.None of the above

1c. Which of the following best explains why it is more difficult to trigger another action potential during the relative refractory period?

A. Voltage-gated K+ channels are open, causing the inside of the cell to become more negative relative to the outside of the cell, which opposes depolarization.

B. Voltage-gated Na+ channels have not finished "resting" and cannot possibly open.

C.Voltage-gated Na+ channels are open and Na+ is flowing into the cell.

D.The neurotransmitter has not yet diffused away from or otherwise been removed from the synaptic cleft.

E. Both voltage-gated Na+ and K+ channels are open, so depolarization is impossible.

Explanation / Answer

1a.

C.Nerve impulses travel from the CNS to the effector along two neurons connected in sequence.

1b.

D. none of the above.

1c.

A. Voltage-gated K+ channels are open, causing the inside of the cell to become more negative relative to the outside of the cell, which opposes depolarization.

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