Question 1

Which of the following best describes the function of afferent (sensory) neurons in the nervous system?

Accepted Answer

They carry information from sensory receptors toward the central nervous system.

Question 2

A patient has a genetic defect that prevents oligodendrocytes from functioning. Which of the following would most likely be affected?

Accepted Answer

Myelination of axons in the central nervous system

Question 3

Which equation is used to predict the equilibrium potential for a single ion across a membrane?

Accepted Answer

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

Question 4

Which of the following best explains why graded potentials decrease in strength as they move through the cytoplasm?

Accepted Answer

Because of current leak and cytoplasmic resistance

Question 5

A sudden increase in $$Na^+$$ permeability in a neuron would favor movement of $$Na^+ in $$which direction, and why?

Accepted Answer

Into the cell, down both its concentration and electrical gradients

Question 6

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

Accepted Answer

Regulating the extracellular environment and helping form the blood-brain barrier

Question 7

Which of the following best describes the difference between electrical and chemical synapses?

Accepted Answer

Electrical synapses allow direct passage of ions between cells, while chemical synapses use neurotransmitters to transmit signals.

Question 8

Which of the following best explains why action potentials are considered 'all-or-none' phenomena?

Accepted Answer

They only occur if the membrane potential reaches threshold, and their size does not vary with stimulus strength.

Question 9

Which of the following is the correct sequence of events during the rising phase of an action potential?

Accepted Answer

Opening of voltage-gated $$Na^+$$ channels, influx of $$Na^+$$, membrane depolarization

Question 10

The Goldman-Hodgkin-Katz (GHK) equation predicts the membrane potential using multiple ions. Which of the following is the correct form of the GHK equation?

Accepted Answer

$$V_m = \frac{RT}{F} \ln \left( \frac{P_{K}[K^+]_{out} + P_{Na}[Na^+]_{out} + P_{Cl}[Cl^-]_{in}}{P_{K}[K^+]_{in} + P_{Na}[Na^+]_{in} + P_{Cl}[Cl^-]_{out}} \right)$$

Question 11

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

Accepted Answer

The neuron will be unable to repolarize efficiently, prolonging the action potential.

Question 12

Which of the following best describes the role of the sodium-potassium pump ($$Na^+/K^+-$$ATPase) in neurons?

Accepted Answer

It maintains the resting membrane potential by actively transporting $$3\ Na^+$$ out and $$2\ K^+ in $$per ATP hydrolyzed.

Question 13

Which of the following glial cells is responsible for producing cerebrospinal fluid (CSF) in the central nervous system?

Accepted Answer

Ependymal cells

Question 14

A patient with multiple sclerosis experiences demyelination in the CNS. Which of the following is a likely consequence?

Accepted Answer

Decreased speed of action potential conduction due to loss of saltatory conduction

Question 15

Which of the following best describes the difference between spatial and temporal summation in postsynaptic neurons?

Accepted Answer

Spatial summation involves inputs from different synapses at the same time; temporal summation involves multiple inputs at the same synapse in rapid succession.

Question 16

Which of the following is a characteristic of ionotropic receptors?

Accepted Answer

They are ligand-gated ion channels that mediate fast synaptic transmission.

Question 17

Which of the following best describes the effect of hypokalemia (low extracellular $$K^+) on $$neuron excitability?

Accepted Answer

It hyperpolarizes the resting membrane potential, making neurons less excitable.

Question 18

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

Accepted Answer

It is the period during which no stimulus, no matter how strong, can initiate another action potential.

Question 19

A neuron receives two excitatory postsynaptic potentials (EPSPs) from different presynaptic neurons at the same time. What is this process called?

Accepted Answer

Spatial summation

Study Guide: Nervous System Organization, Neuronal Signaling, and Synaptic Communication

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