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

Question 1

Which of the following best explains why the inside of a neuron is more negative than the outside at rest?

Accepted Answer

Negatively charged proteins are abundant inside the cell and cannot cross the membrane.

Question 2

A neuron’s resting membrane potential is maintained primarily by which mechanism?

Accepted Answer

Active transport by the Na+-K+ ATPase pump, which moves 3 Na+ out for every 2 K+ in.

Question 3

If the membrane potential of a neuron changes from $$-70\,	ext{mV} to$$ $$-55\,	ext{mV}$$, which event is most likely to occur?

Accepted Answer

Voltage-gated Na+ channels will open, initiating an action potential.

Question 4

Which statement correctly describes the 'all-or-none' rule of action potentials?

Accepted Answer

If threshold is reached, the neuron fires at maximum voltage; if not, no action potential occurs.

Question 5

During the absolute refractory period, which of the following is true?

Accepted Answer

No action potential can be generated, regardless of stimulus strength.

Question 6

Which type of membrane channel is most directly responsible for the initiation of an action potential at the axon hillock?

Accepted Answer

Voltage-gated Na+ channels

Question 7

A patient with multiple sclerosis is likely to experience which of the following effects on nerve conduction?

Accepted Answer

Slower propagation of action potentials due to patchy loss of myelin.

Question 8

Which equation best represents the activity of the sodium-potassium pump in maintaining the resting membrane potential?

Accepted Answer

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

Question 9

Which of the following best describes saltatory propagation in myelinated axons?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, increasing speed.

Question 10

Which of the following is a characteristic of local (graded) potentials, but NOT action potentials?

Accepted Answer

They are decremental, meaning the signal weakens as it travels.

Question 11

A neuron receives both excitatory and inhibitory signals. Which of the following best describes the outcome?

Accepted Answer

The balance between excitatory (depolarizing) and inhibitory (hyperpolarizing) signals determines whether an action potential is generated.

Question 12

Which of the following best explains why myelination increases the speed of action potential propagation?

Accepted Answer

Myelination insulates the axon, allowing Na+ ions to diffuse rapidly between nodes of Ranvier.

Question 13

Which of the following fiber types would transmit a pain signal from a stubbed toe to the CNS?

Accepted Answer

Type C fibers: smallest diameter, unmyelinated, slowest speed.

Question 14

If a neuron’s membrane potential is hyperpolarized, which of the following is most likely occurring?

Accepted Answer

K+ channels remain open longer, allowing more K+ to leave the cell.

Question 15

Which scenario best illustrates the decremental nature of local potentials?

Accepted Answer

A signal initiated at the dendrite becomes weaker as it travels toward the axon hillock.

Question 16

Which of the following is true regarding the energy requirements of nervous tissue?

Accepted Answer

Nervous tissue uses high levels of ATP, oxygen, and glucose to maintain ion gradients.

Question 17

Which of the following best describes the effect of axon diameter on propagation speed?

Accepted Answer

Larger diameter axons have lower resistance and faster propagation.

Question 18

Which of the following channels would be most likely to open in response to a neurotransmitter binding to a dendrite?

Accepted Answer

Chemically regulated (ligand-gated) channels

Question 19

A neuron is exposed to a strong mechanical stimulus. Which channel type is most likely to open?

Accepted Answer

Mechanically regulated channels

Question 20

Which of the following best describes the electrochemical gradient for an ion?

Accepted Answer

It is the sum of the chemical and electrical forces acting on the ion across the cell membrane.

Neurophysiology: Electrical Properties and Signal Transmission in Neurons

Study Guide - Practice Questions