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 are local, while action potentials are all-or-nothing and propagate without decrement over long distances.

Question 2

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

Accepted Answer

The neuron will reach threshold and initiate an action potential.

Question 3

During the rising phase of an action potential, which ion channels are primarily responsible for the rapid depolarization?

Accepted Answer

Voltage-gated Na$$^+$$ channels opening, allowing Na$$^+$$ influx.

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 backward propagation due to inactivated Na$$^+$$ channels.

Question 5

Saltatory conduction is faster than contiguous conduction because:

Accepted Answer

Myelin sheaths allow action potentials to jump between nodes of Ranvier.

Question 6

Which of the following events occurs first at a chemical synapse after an action potential arrives at the axon terminal?

Accepted Answer

Voltage-gated Ca$$^{2+}$$ channels open, allowing Ca$$^{2+}$$ influx.

Question 7

A postsynaptic neuron receives both excitatory (EPSP) and inhibitory (IPSP) inputs. Which of the following best describes how these inputs are integrated?

Accepted Answer

EPSPs and IPSPs are summed both temporally and spatially to determine if threshold is reached.

Question 8

Which of the following is a correct sequence of events for the cAMP second messenger system?

Accepted Answer

Ligand binds receptor → G protein activates adenylyl cyclase → ATP is converted to cAMP → cAMP activates protein kinase A

Question 9

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

Accepted Answer

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

Question 10

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

Accepted Answer

Repolarization will be delayed, prolonging the action potential.

Question 11

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 12

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

Accepted Answer

They are all-or-nothing responses.

Question 13

Which of the following best explains why neurotransmitters must be rapidly removed from the synaptic cleft?

Accepted Answer

To prevent continuous stimulation or inhibition of the postsynaptic cell.

Question 14

Which of the following is a direct effect of activating a G protein-coupled receptor (GPCR) on the cell membrane?

Accepted Answer

Activation of an intracellular amplifier enzyme such as adenylyl cyclase.

Question 15

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

Accepted Answer

Temporal summation

Question 16

Which of the following best describes the effect of an inhibitory postsynaptic potential (IPSP) on a neuron?

Accepted Answer

It hyperpolarizes the neuron, making it less likely to fire an action potential.

Question 17

Which of the following is a correct statement about the absolute refractory period?

Accepted Answer

It occurs because voltage-gated Na$$^+$$ channels are inactivated and cannot reopen immediately.

Question 18

Which of the following best describes the process of signal amplification in a second messenger system?

Accepted Answer

A single ligand-receptor interaction activates multiple intracellular molecules, leading to a large cellular response.

Neuronal Physiology and Cell Communication: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드