$$3\ \text{Na}^+\ \text{out},\ 2\ \text{K}^+\ \text{in}$$

Question 1

Which of the following best describes a graded potential in a neuron?

Accepted Answer

A local change in membrane voltage whose magnitude depends on the strength of the stimulus and fades with distance.

Question 2

Where do graded potentials typically occur in a motor neuron?

Accepted Answer

Dendrites and cell body

Question 3

Which type of ion channel opens in response to a neurotransmitter binding to its receptor?

Accepted Answer

Chemically (ligand) gated ion channel

Question 4

What is the resting membrane potential ($$RMP) of a $$typical neuron?

Accepted Answer

$$-70\ 	ext{mV}$$

Question 5

Which equation best represents the action of the Na⁺/K⁺ ATPase pump?

Accepted Answer

$$3\ 	ext{Na}^+\ 	ext{out},\ 2\ 	ext{K}^+\ 	ext{in}$$

Question 6

During the depolarization phase of an action potential, which ion moves and in which direction?

Accepted Answer

Na⁺ moves into the cell

Question 7

What happens to the membrane potential during hyperpolarization?

Accepted Answer

It falls below the resting level

Question 8

Which phase of the action potential is characterized by the inactivation of Na⁺ channels and the opening of K⁺ channels?

Accepted Answer

Repolarization

Question 9

What is the main reason action potentials only propagate in one direction along an axon?

Accepted Answer

The absolute refractory period prevents backward propagation

Question 10

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

Accepted Answer

Action potentials jump from node to node (saltatory conduction)

Question 11

A patient with multiple sclerosis (MS) is likely to experience which of the following changes in nervous tissue?

Accepted Answer

Loss of myelin leading to slower and disrupted action potential conduction

Question 12

Which of the following is true about the absolute refractory period?

Accepted Answer

Voltage-gated Na⁺ channels are open or inactivating, preventing any new action potential

Question 13

How does the nervous system code for the intensity of a stimulus?

Accepted Answer

By increasing the frequency of action potentials

Question 14

Which of the following would most likely occur if a local anesthetic blocks voltage-gated Na⁺ channels?

Accepted Answer

No action potentials would be generated

Question 15

If a neuron is exposed to a neurotoxin that increases K⁺ permeability, what is the most likely effect on the resting membrane potential?

Accepted Answer

The membrane potential would become more negative (hyperpolarized)

Question 16

Which of the following best describes the relationship between stimulus strength and graded potential amplitude?

Accepted Answer

Stronger stimulus produces a larger graded potential amplitude

Question 17

During which phase of the action potential does the membrane potential briefly fall below the resting level?

Accepted Answer

Hyperpolarization

Question 18

Which of the following is a characteristic of graded potentials but NOT action potentials?

Accepted Answer

They fade with distance from the stimulus

Question 19

A neuron receives a stimulus that causes Na⁺ to enter the cell. What is the effect on the membrane potential?

Accepted Answer

The inside of the cell becomes less negative (depolarization)

Question 20

Which of the following best explains why larger diameter axons conduct action potentials faster than smaller diameter axons?

Accepted Answer

Larger diameter axons have lower resistance to current flow

Fundamentals of the Nervous System and Nervous Tissue: Membrane Potentials and Action Potentials

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