Question 1

Which of the following best describes the role of glial cells in the nervous system?

Accepted Answer

They nourish, support, and insulate neurons.

Question 2

A neuron at rest has a membrane potential of approximately $$-70\ \mathrm{mV}. $$Which of the following mechanisms is primarily responsible for maintaining this resting potential?

Accepted Answer

Active transport of potassium and sodium ions by the sodium-potassium pump.

Question 3

Which equation would you use to calculate the equilibrium potential for potassium ($$K^+) $$across a neuronal membrane, and what is the value given $$[K^+]_{out} = 5\ \mathrm{mM}$$ and $$[K^+]_{in} = 140\ \mathrm{mM}$$?

Accepted Answer

$$E_K = 62\ \mathrm{mV} \log \left( \frac{[K^+]_{out}}{[K^+]_{in}} \right)$$; $$E_K = -90\ \mathrm{mV}$$

Question 4

During an action potential, which event occurs immediately after the membrane potential reaches threshold?

Accepted Answer

Voltage-gated sodium channels open, causing rapid depolarization.

Question 5

Why do action potentials only travel in one direction along an axon?

Accepted Answer

Inactivated sodium channels behind the action potential prevent backward propagation.

Question 6

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Action potentials jump between nodes of Ranvier in a process called saltatory conduction.

Question 7

A patient is exposed to a toxin that blocks voltage-gated calcium channels at the synaptic terminal. What is the most likely effect on neuronal communication?

Accepted Answer

Neurotransmitter release into the synaptic cleft will be inhibited.

Question 8

Which of the following scenarios would most likely result in an inhibitory postsynaptic potential (IPSP)?

Accepted Answer

Opening of ligand-gated potassium or chloride channels in the postsynaptic membrane.

Question 9

Which process is responsible for terminating neurotransmitter signaling at a chemical synapse?

Accepted Answer

Enzymatic breakdown or reuptake of neurotransmitter from the synaptic cleft.

Question 10

A neuron receives multiple excitatory postsynaptic potentials (EPSPs) in rapid succession at a single synapse. What is this phenomenon called, and what is its effect?

Accepted Answer

Temporal summation; it increases the likelihood of reaching threshold.

Question 11

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

Accepted Answer

Electrical synapses transmit signals via gap junctions, while chemical synapses use neurotransmitters.

Question 12

Which of the following is a correct sequence of information flow in a typical nervous system?

Accepted Answer

Sensory input → Integration → Motor output

Question 13

Which of the following would most likely occur if the sodium-potassium pump in a neuron stopped functioning?

Accepted Answer

The resting membrane potential would dissipate, and the neuron could not generate action potentials.

Question 14

Which of the following neurotransmitters is classified as a biogenic amine and is involved in mood regulation?

Accepted Answer

Serotonin

Question 15

A mutation causes voltage-gated sodium channels to remain open longer than normal during an action potential. What is the most likely effect on the action potential?

Accepted Answer

The action potential will have a higher and broader peak.

Question 16

Which of the following best explains why a single EPSP is usually insufficient to trigger an action potential in a postsynaptic neuron?

Accepted Answer

The depolarization caused by a single EPSP is too small to reach threshold.

Question 17

Which of the following is a function of metabotropic receptors at synapses?

Accepted Answer

Activate a signal transduction pathway involving second messengers.

Question 18

Which of the following best describes the effect of opening ligand-gated chloride channels in the postsynaptic membrane?

Accepted Answer

It causes hyperpolarization, leading to an IPSP.

Question 19

Which of the following is a real-world example of the importance of myelin sheaths in the nervous system?

Accepted Answer

Multiple sclerosis, a disease where myelin is degraded, resulting in slower nerve conduction and muscle weakness.

Neurons, Synapses, and Signaling: Structure and Function in the Nervous System

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