Question 1

Which of the following best describes the function of astrocytes in the central nervous system (CNS)?

Accepted Answer

They support and brace neurons, regulate the chemical environment, and participate in information processing.

Question 2

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

Accepted Answer

Voltage-gated Na$$^+$$ channels

Question 3

Which of the following statements about the absolute refractory period is correct?

Accepted Answer

It ensures that each action potential is a separate, all-or-none event and enforces one-way transmission.

Question 4

A patient is exposed to a toxin that selectively blocks voltage-gated Na$$^+$$ channels. What is the most likely effect on neuronal signaling?

Accepted Answer

Action potentials will not be generated, preventing neural communication.

Question 5

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

Accepted Answer

Myelin allows action potentials to jump from one node of Ranvier to the next, a process called saltatory conduction.

Question 6

Which of the following neurotransmitters is generally inhibitory in the adult brain and acts primarily through ionotropic receptors that allow Cl$$^-$$ influx?

Accepted Answer

GABA

Question 7

A neuron receives simultaneous excitatory postsynaptic potentials (EPSPs) from multiple presynaptic neurons. This is an example of:

Accepted Answer

Spatial summation

Question 8

Which of the following best describes the difference between ionotropic and metabotropic neurotransmitter receptors?

Accepted Answer

Ionotropic receptors directly open ion channels for rapid responses, while metabotropic receptors activate second messenger systems for slower, prolonged effects.

Question 9

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

Accepted Answer

Voltage-gated K$$^+$$ channels open, allowing K$$^+ to $$exit the cell.

Question 10

Which glial cell type is responsible for forming the myelin sheath in the peripheral nervous system (PNS)?

Accepted Answer

Schwann cells

Question 11

A neuron is exposed to a drug that increases the permeability of its membrane to Cl$$^-. $$What is the most likely effect on the postsynaptic potential?

Accepted Answer

It will generate an inhibitory postsynaptic potential (IPSP).

Question 12

Which of the following best explains why action potentials are unidirectional along an axon?

Accepted Answer

The absolute refractory period prevents the action potential from traveling backward.

Question 13

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

Accepted Answer

They decay in amplitude with distance from the site of origin.

Question 14

A neuron is at rest with a membrane potential of $$-70\ \mathrm{mV}. If $$the threshold for action potential initiation is $$-55\ \mathrm{mV}$$, what must occur for the neuron to fire an action potential?

Accepted Answer

The membrane must depolarize to at least $$-55\ \mathrm{mV}.$$

Question 15

Which of the following scenarios would most likely result in temporal summation at a postsynaptic neuron?

Accepted Answer

A single presynaptic neuron fires rapidly in succession, releasing neurotransmitter repeatedly.

Question 16

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

Accepted Answer

It depolarizes the postsynaptic membrane, bringing it closer to threshold for firing an action potential.

Question 17

Which of the following is a property of neurons that distinguishes them from neuroglia?

Accepted Answer

Neurons are capable of generating and transmitting electrical impulses.

Question 18

A patient is given a drug that blocks muscarinic acetylcholine (ACh) receptors. Which of the following effects is most likely to be observed?

Accepted Answer

Reduced effects of ACh on target organs that use metabotropic receptors.

Question 19

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

Accepted Answer

EPSPs are graded potentials that decay with distance and usually do not reach threshold at the axon hillock.

Nerve Impulses and Synaptic Transmission: Cells, Action Potentials, and Synapses

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