Question 1

Which of the following best describes the main function of myelin in the nervous system?

Accepted Answer

To increase the speed of nerve impulse conduction along the axon by enabling saltatory propagation.

Question 2

A patient is experiencing muscle weakness due to demyelination of axons in the central nervous system. Which type of neuroglial cell is most likely affected?

Accepted Answer

Oligodendrocytes

Question 3

During the resting membrane potential, which of the following best describes the distribution of ions across the neuronal membrane?

Accepted Answer

There is a higher concentration of $$\mathrm{Na^+}$$ outside the cell and a higher concentration of $$\mathrm{K^+}$$ inside the cell.

Question 4

Which of the following best explains the 'all-or-none' principle of action potentials?

Accepted Answer

If threshold is reached, an action potential of fixed size will occur; if not, no action potential is generated.

Question 5

A neuron receives a stimulus that causes its membrane potential to change from $$-70\ \mathrm{mV} to$$ $$+30\ \mathrm{mV}. $$Which process is occurring?

Accepted Answer

Depolarization

Question 6

Which of the following is a correct sequence of events during synaptic transmission at a chemical synapse?

Accepted Answer

Action potential arrives at axon terminal $$\rightarrow$$ $$\mathrm{Ca$$^{2+}$$}$$ channels open $$\rightarrow$$ neurotransmitter released $$\rightarrow$$ postsynaptic receptor activation

Question 7

Which of the following best distinguishes between the central nervous system (CNS) and the peripheral nervous system (PNS)?

Accepted Answer

The CNS consists of the brain and spinal cord, while the PNS includes all neural tissue outside the CNS.

Question 8

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

Accepted Answer

Maintaining the blood-brain barrier

Question 9

A person touches a hot stove and quickly withdraws their hand. Which type of neuron is responsible for carrying the signal from the spinal cord to the muscles?

Accepted Answer

Efferent (motor) neuron

Question 10

Which of the following best describes saltatory propagation?

Accepted Answer

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

Question 11

Which neurotransmitter is primarily involved in stimulating skeletal muscle contraction at the neuromuscular junction?

Accepted Answer

Acetylcholine

Question 12

Which of the following scenarios best illustrates the inhibitory effect of a neurotransmitter?

Accepted Answer

A neurotransmitter binds to a postsynaptic receptor, causing $$\mathrm{Cl^-}$$ channels to open and hyperpolarize the membrane.

Question 13

Which of the following best describes the role of microglia in the central nervous system?

Accepted Answer

They act as immune cells, removing debris and pathogens by phagocytosis.

Question 14

A neuron is unable to generate another action potential immediately after one has occurred. This period is known as:

Accepted Answer

The absolute refractory period

Question 15

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

Accepted Answer

The refractory period prevents the action potential from traveling backward.

Question 16

Which of the following is a correct match between a neurotransmitter and its primary function?

Accepted Answer

GABA: main inhibitory neurotransmitter in the CNS

Question 17

A patient has a genetic mutation that causes voltage-gated $$\mathrm{Na^+}$$ channels to remain open longer than normal during an action potential. What is the most likely effect on the action potential?

Accepted Answer

The depolarization phase will be prolonged, and the action potential may be larger or last longer.

Question 18

Which of the following best describes the function of interneurons?

Accepted Answer

They connect sensory and motor neurons within the CNS and are involved in integration.

Question 19

Which of the following would most likely disrupt the generation of an action potential?

Accepted Answer

Blocking voltage-gated $$\mathrm{Na^+}$$ channels with a toxin

Question 20

A person is exposed to a drug that increases the activity of acetylcholinesterase at the neuromuscular junction. What is the most likely effect?

Accepted Answer

Decreased stimulation of skeletal muscle due to faster breakdown of acetylcholine

Nervous System: Structure, Function, and Physiology Study Guide

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