Question 1

Which of the following best explains why the inside of a resting neuron is negatively charged relative to the outside?

Accepted Answer

The membrane is more permeable to K\^+ than to Na\^+, allowing K\^+ to diffuse out, leaving behind negatively charged proteins.

Question 2

If the resting membrane potential of a neuron is approximately $$-70\ \mathrm{mV}$$, what would happen to the membrane potential if extracellular K\^+ concentration increased significantly?

Accepted Answer

The membrane potential would become less negative (depolarize).

Question 3

Which equation can be used to calculate the equilibrium potential for a specific ion across a membrane?

Accepted Answer

The Nernst equation: $$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 4

During an action potential, which event is responsible for the rapid depolarization phase?

Accepted Answer

Opening of voltage-gated Na\^+ channels, allowing Na\^+ to enter the cell.

Question 5

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

Accepted Answer

Action potentials only occur if the membrane potential reaches threshold; otherwise, none occurs.

Question 6

A patient with multiple sclerosis experiences slowed nerve conduction. Which of the following best explains this symptom?

Accepted Answer

Loss of myelin sheaths disrupts saltatory conduction, causing slower transmission of action potentials.

Question 7

Which of the following factors would most likely increase the conduction velocity of an action potential along an axon?

Accepted Answer

Increasing the diameter of the axon and adding a myelin sheath.

Question 8

Which statement about graded potentials is correct?

Accepted Answer

Graded potentials decrease in strength as they spread from the point of origin.

Question 9

What is the primary function of voltage-gated Na\^+ channels during the generation of an action potential?

Accepted Answer

To allow Na\^+ influx, causing rapid depolarization of the membrane.

Question 10

Which of the following best describes the refractory period in neurons?

Accepted Answer

A period when voltage-gated Na\^+ channels are inactivated and the neuron cannot fire another action potential.

Question 11

Which of the following is TRUE regarding chemical synapses?

Accepted Answer

They use neurotransmitters to transmit signals across a synaptic cleft.

Question 12

A neuron receives simultaneous excitatory and inhibitory inputs. Which of the following best describes the outcome?

Accepted Answer

The net effect depends on the sum of all inputs; if threshold is reached, an action potential will occur.

Question 13

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

Accepted Answer

The refractory period prevents re-excitation of the membrane behind the action potential.

Question 14

Which of the following would most likely result from blocking voltage-gated Na\^+ channels in a neuron?

Accepted Answer

Failure to generate action potentials.

Question 15

Which of the following best describes saltatory conduction?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, speeding transmission.

Question 16

Which of the following is a consequence of demyelination in the central nervous system?

Accepted Answer

Loss of saltatory conduction, leading to slower and less efficient nerve transmission.

Question 17

Which of the following best describes the role of the synaptic cleft in chemical synapses?

Accepted Answer

It separates the presynaptic and postsynaptic membranes, allowing neurotransmitter diffusion.

Question 18

Which of the following would most likely increase the frequency of action potentials in a neuron?

Accepted Answer

Increasing the strength of the stimulus above threshold.

Question 19

Which of the following is TRUE regarding the propagation of an action potential?

Accepted Answer

It is regenerated at each segment of the axon, allowing it to travel long distances without decrement.

Resting Membrane Potential, Action Potentials, and Synaptic Transmission

Guida di studio - Domande di pratica

Study guide - Flashcard