Question 1

Which of the following best describes the role of the sodium-potassium pump in establishing the resting membrane potential of a neuron?

Accepted Answer

It uses ATP to pump three sodium ions out of the cell and two potassium ions into the cell, creating and maintaining ion gradients.

Question 2

A neuron is exposed to a toxin that blocks voltage-gated potassium channels. What is the most likely effect on the action potential?

Accepted Answer

The repolarization phase will be prolonged, and the action potential will last longer.

Question 3

Which of the following equations correctly represents the Nernst equation for calculating the equilibrium potential ($$E_{ion}) $$for a monovalent ion at body temperature?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \frac{[ion]_{out}}{[ion]_{in}}$$

Question 4

Which glial cell type is primarily responsible for forming the myelin sheath in the central nervous system (CNS)?

Accepted Answer

Oligodendrocytes

Question 5

During the depolarizing phase of the action potential, which of the following events occurs?

Accepted Answer

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

Question 6

What is the primary effect of increasing membrane permeability to chloride ions ($$Cl^-) in a $$neuron?

Accepted Answer

It causes hyperpolarization, making the neuron less excitable.

Question 7

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

Accepted Answer

Voltage-gated sodium channels become inactivated immediately after opening, creating a refractory period.

Question 8

A patient is exposed to sarin gas, a potent acetylcholinesterase inhibitor. What is the most likely effect on synaptic transmission?

Accepted Answer

Acetylcholine will accumulate in the synaptic cleft, causing prolonged stimulation of postsynaptic cells.

Question 9

Which of the following is a key difference between electrical and chemical synapses?

Accepted Answer

Electrical synapses transmit signals with no synaptic delay, while chemical synapses have a delay due to neurotransmitter release.

Question 10

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

Accepted Answer

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

Question 11

Which of the following statements about ligand-gated ion channels is correct?

Accepted Answer

They open when a specific molecule binds to them, allowing ions to flow across the membrane.

Question 12

A neuron receives a subthreshold depolarization. What is the most likely outcome?

Accepted Answer

The membrane potential will return to resting potential without generating an action potential.

Question 13

Which of the following is a criterion for a molecule to be classified as a neurotransmitter?

Accepted Answer

It must elicit the appropriate response when introduced to the synaptic cleft.

Question 14

Which of the following best explains the effect of myelination on the speed of nerve impulse conduction?

Accepted Answer

Myelination decreases the ability of the membrane to retain electrical charge, allowing action potentials to travel faster.

Question 15

Which of the following events occurs first during chemical synaptic transmission?

Accepted Answer

Voltage-gated calcium channels open in the presynaptic terminal.

Question 16

Which of the following drugs would most likely increase the duration of neurotransmitter action in the synaptic cleft?

Accepted Answer

A drug that blocks neurotransmitter reuptake into the presynaptic cell.

Question 17

Which of the following best describes the Hodgkin cycle during the initiation of an action potential?

Accepted Answer

A positive feedback loop where Na+ influx causes further depolarization and opening of more Na+ channels.

Question 18

Which of the following is a function of astrocytes in the nervous system?

Accepted Answer

Controlling access of blood-borne components into the extracellular fluid around nerve cells.

Question 19

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

Accepted Answer

To prevent abnormally prolonged stimulation or inhibition of the postsynaptic neuron.

Signal Transduction Mechanisms: Electrical and Synaptic Signaling in Neurons

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