Question 1

Which of the following best describes the resting membrane potential of a typical neuron?

Accepted Answer

It is approximately -70 mV, with the inside of the cell more negative than the outside.

Question 2

A neuron is exposed to Chemical X, which blocks voltage-gated sodium channels. What is the most likely effect on the neuron's ability to generate an action potential?

Accepted Answer

The neuron will be unable to depolarize and generate an action potential.

Question 3

Which equation best represents the relationship between current ($$I$$), voltage ($$V$$), and resistance ($$R) $$across a cell membrane?

Accepted Answer

$$V = I 	imes R$$

Question 4

What is the primary function of the sodium-potassium pump in maintaining the resting membrane potential?

Accepted Answer

It actively transports 3 Na+ out and 2 K+ into the cell, maintaining the negative resting potential.

Question 5

During the generation of an action potential, which event occurs immediately after the membrane reaches threshold?

Accepted Answer

Voltage-gated Na+ channels open, causing rapid depolarization.

Question 6

Which of the following best explains why action potentials only propagate in one direction along an axon?

Accepted Answer

The refractory period prevents the previous segment from responding to another action potential.

Question 7

A graded potential is most likely to lead to an action potential if it:

Accepted Answer

Depolarizes the membrane to the threshold value.

Question 8

Which type of ion channel is most abundant on the dendrites and cell body of a neuron, facilitating synaptic communication?

Accepted Answer

Chemically gated (ligand-gated) ion channels

Question 9

Saltatory propagation of an action potential is characterized by:

Accepted Answer

Action potential 'jumping' from one node of Ranvier to the next in myelinated axons.

Question 10

Which of the following axon types has the fastest propagation speed for action potentials?

Accepted Answer

Type A fibers: myelinated, 4-20 \mu m diameter

Question 11

If the plasma membrane of a neuron were freely permeable to sodium ions, what would happen to its membrane potential?

Accepted Answer

The membrane potential would approach the equilibrium potential of sodium, becoming more positive.

Question 12

Which of the following best describes the 'all-or-none' principle of action potentials?

Accepted Answer

Any stimulus above threshold generates identical action potentials.

Question 13

A patient is given Chemical Y, which blocks voltage-gated potassium channels. What is the most likely effect on the action potential?

Accepted Answer

Repolarization will be delayed, prolonging the action potential.

Question 14

Which of the following is a correct sequence of events during the generation of an action potential?

Accepted Answer

Opening of voltage-gated Na+ channels, followed by opening of voltage-gated K+ channels.

Question 15

Which of the following best explains why not all axons in the nervous system are large and myelinated?

Accepted Answer

Physical space limitations make it impossible for all axons to be large and myelinated.

Question 16

Which of the following would most likely result from a decrease in extracellular potassium levels (Chemical Z)?

Accepted Answer

The resting membrane potential would become more negative (hyperpolarized).

Question 17

Which type of ion channel opens in response to physical distortion of the membrane surface, such as pressure or vibration?

Accepted Answer

Mechanically gated ion channels

Question 18

Which of the following best describes the propagation of an action potential in an unmyelinated axon?

Accepted Answer

Continuous propagation along the entire axolemma.

Question 19

Which of the following is true regarding the relationship between axon diameter and propagation speed?

Accepted Answer

Larger diameter axons conduct action potentials faster.

Question 20

Which of the following best describes a graded (local) potential?

Accepted Answer

It is a localized change in membrane potential that decreases in intensity with distance from the stimulus.

Nervous Tissue: Membrane Potential, Action Potential, and Neurotransmission

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