Question 1

During an action potential, the membrane potential becomes most positive when which of the following occurs?

Accepted Answer

The sodium channels only are open

Question 2

Which ion channel activity is primarily responsible for the membrane potential becoming more negative during the repolarization phase of an action potential?

Accepted Answer

Potassium channels only are open

Question 3

Which lipid, produced by Schwann cells, insulates axons to increase the velocity of action potentials?

Accepted Answer

Myelin, Schwann cells

Question 4

Which brain structure, enlarged in birds and mammals and located above the brainstem, is primarily responsible for coordinating movements?

Accepted Answer

Cerebellum

Question 5

The midbrain, which is prominent in bony fishes, includes which of the following structures?

Accepted Answer

Optic lobes

Question 6

If a mutation caused Schwann cells to produce less myelin, what would be the most likely effect on nerve impulse transmission?

Accepted Answer

The velocity of action potentials would decrease

Question 7

Which of the following best describes the role of sodium channels during the depolarization phase of an action potential?

Accepted Answer

They open, allowing sodium ions to enter the cell

Question 8

A patient is diagnosed with multiple sclerosis, a disease that damages myelin in the central nervous system. Which equation best describes the effect on the speed of action potential propagation?

Accepted Answer

$$v = \frac{d}{t}$$, where $$v is $$velocity, $$d is $$distance, and $$t is $$time; $$v$$ decreases as myelin is lost

Question 9

Which of the following scenarios would most likely result in hyperpolarization of a neuron?

Accepted Answer

Opening of potassium channels

Question 10

During the refractory period of an action potential, which statement is most accurate?

Accepted Answer

Sodium channels are inactivated and cannot open

Question 11

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Myelin allows action potentials to jump between nodes of Ranvier, a process called saltatory conduction

Question 12

Which of the following is a direct consequence of potassium channels opening during an action potential?

Accepted Answer

Potassium ions exit the cell, causing repolarization

Question 13

A researcher measures the membrane potential of a neuron and finds it to be $$+40 mV. $$Which ion channel is most likely open at this time?

Accepted Answer

Sodium channels

Question 14

Which of the following best describes the function of the cerebellum?

Accepted Answer

Coordinates voluntary movements and balance

Question 15

If the optic lobes of a fish's midbrain were damaged, which function would most likely be impaired?

Accepted Answer

Vision

Question 16

Which of the following is NOT a function of myelin?

Accepted Answer

Synthesizing neurotransmitters

Question 17

Which equation best represents the Nernst equation for calculating the equilibrium potential of potassium ions ($$K^+) $$across a neuronal membrane?

Accepted Answer

$$E_K = \frac{RT}{zF} \ln \left( \frac{[K^+]_{out}}{[K^+]_{in}} \right)$$

Question 18

A neuron is exposed to a drug that blocks sodium channels. What is the most likely effect on the action potential?

Accepted Answer

The neuron will not be able to initiate an action potential

Question 19

Which of the following best describes the sequence of ion channel openings during a typical action potential?

Accepted Answer

Sodium channels open first, followed by potassium channels

Question 20

Which cell type is responsible for producing myelin in the peripheral nervous system?

Accepted Answer

Schwann cells

Neural Signaling and Brain Structure: Key Concepts in General Biology

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