Question 1

Which of the following best describes the difference between graded potentials and action potentials in neurons?

Accepted Answer

Graded potentials vary in amplitude with stimulus strength and decay with distance, while action potentials are all-or-nothing and propagate without decrement.

Question 2

During the rising phase of an action potential, which of the following events occurs at the membrane?

Accepted Answer

Voltage-gated Na$$^+$$ channels open, allowing Na$$^+ to $$enter the cell.

Question 3

A neuron is at rest with a membrane potential of $$-70\ \mathrm{mV}. If a $$stimulus causes the membrane potential to reach $$-50\ \mathrm{mV}$$, what is most likely to occur?

Accepted Answer

The threshold for an action potential is reached, and an action potential will be initiated.

Question 4

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

Accepted Answer

The absolute refractory period prevents the region of membrane behind the action potential from being re-excited.

Question 5

Saltatory conduction in myelinated axons is faster than contiguous conduction because:

Accepted Answer

Action potentials jump from node to node, reducing the number of times the membrane must depolarize.

Question 6

Which of the following is a correct sequence of events at a chemical synapse?

Accepted Answer

Action potential arrives at axon terminal → Voltage-gated Ca$$^{2+}$$ channels open → Neurotransmitter is released into synaptic cleft

Question 7

A postsynaptic neuron receives simultaneous excitatory and inhibitory inputs. What determines whether it will fire an action potential?

Accepted Answer

The spatial and temporal summation of all excitatory and inhibitory postsynaptic potentials

Question 8

Which of the following best describes the function of the Na$$^+/K$^+$$ pump after an action potential?

Accepted Answer

It restores the original ion concentration gradients by pumping Na$$^+$$ out and K$$^+ in.$$

Question 9

Which of the following is an example of paracrine signaling?

Accepted Answer

A cell releasing a chemical messenger that acts on neighboring cells in the same tissue

Question 10

Which of the following is a correct description of the cAMP second messenger system?

Accepted Answer

A ligand binds to a G protein-coupled receptor, activating adenylyl cyclase, which converts ATP to cAMP.

Question 11

A patient is exposed to a toxin that blocks voltage-gated K$$^+$$ channels. What effect would this have on the action potential?

Accepted Answer

The repolarization phase would be prolonged, and the neuron would remain depolarized longer.

Question 12

Which of the following best explains why graded potentials decrease in strength as they spread from the point of origin?

Accepted Answer

Current leaks out of the cell through the membrane, reducing the amplitude with distance.

Question 13

Which of the following is NOT a characteristic of an action potential?

Accepted Answer

Its amplitude depends on the strength of the stimulus.

Question 14

Which of the following is a function of the calcium second messenger system?

Accepted Answer

Forms a complex with calmodulin to activate proteins

Question 15

A neuron receives two excitatory postsynaptic potentials (EPSPs) in rapid succession at the same synapse. This is an example of:

Accepted Answer

Temporal summation

Question 16

Which of the following best describes the role of voltage-gated Na$$^+$$ channel inactivation during the action potential?

Accepted Answer

It prevents further Na$$^+$$ entry, contributing to the absolute refractory period.

Question 17

Which of the following is a property of receptor-channel membrane receptors?

Accepted Answer

They directly open or close ion channels in response to ligand binding.

Question 18

Which of the following best describes the process of signal amplification in cell signaling?

Accepted Answer

A single ligand-receptor interaction leads to the activation of many intracellular molecules through a cascade.

Question 19

Which of the following is true regarding the equilibrium potentials for Na$$^+$$ and K$$^+$$?

Accepted Answer

$$E_{Na^+} is $$positive (about $$+60\ \mathrm{mV}$$), while $$E_{K^+} is $$negative (about $$-90\ \mathrm{mV}).$$

Neuronal Physiology: Membrane Potentials, Action Potentials, and Cell Communication

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드