Q: Which of the following equations correctly represents the action of the sodium-potassium exchange pump?

$$3\ \mathrm{Na}^+_{\text{(in)}} \rightarrow 3\ \mathrm{Na}^+_{\text{(out)}}$$ and $$2\ \mathrm{K}^+_{\text{(out)}} \rightarrow 2\ \mathrm{K}^+_{\text{(in)}}$$

Question 1

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

Accepted Answer

It integrates, processes, and coordinates sensory and motor commands.

Question 2

A patient suffers a spinal cord injury that disrupts the motor (efferent) division of the peripheral nervous system (PNS). Which of the following effects would most likely occur?

Accepted Answer

The patient would lose voluntary and involuntary control of muscle and gland activity.

Question 3

Which type of neuron is most commonly found in the central nervous system and is responsible for higher functions such as memory and learning?

Accepted Answer

Interneuron

Question 4

Which glial cell is primarily responsible for maintaining the blood-brain barrier in the CNS?

Accepted Answer

Astrocyte

Question 5

A toxin blocks voltage-gated sodium channels in neurons. What is the most likely effect on neuronal function?

Accepted Answer

Action potentials cannot be generated, preventing nerve signal transmission.

Question 6

Which of the following best explains why CNS neurons are rarely replaced after injury?

Accepted Answer

They lack centrioles and cannot divide.

Question 7

Which of the following equations correctly represents the action of the sodium-potassium exchange pump?

Accepted Answer

$$3\ \mathrm{Na}^+_{	ext{(in)}} ightarrow 3\ \mathrm{Na}^+_{	ext{(out)}}$$ and $$2\ \mathrm{K}^+_{	ext{(out)}} ightarrow 2\ \mathrm{K}^+_{	ext{(in)}}$$

Question 8

Which of the following is TRUE regarding saltatory propagation of action potentials?

Accepted Answer

It occurs in myelinated axons and is faster than continuous propagation.

Question 9

A patient presents with a loss of sensation in the skin and an inability to move skeletal muscles voluntarily. Which divisions of the nervous system are most likely affected?

Accepted Answer

Somatic sensory and somatic motor divisions of the PNS

Question 10

Which of the following best describes the effect of opening chemically gated potassium channels on the postsynaptic membrane?

Accepted Answer

It causes hyperpolarization, making the membrane potential more negative.

Question 11

Which of the following scenarios best illustrates spatial summation?

Accepted Answer

Multiple synapses are activated simultaneously, and their combined effect reaches threshold.

Question 12

Which neuroglia are responsible for producing myelin in the peripheral nervous system (PNS)?

Accepted Answer

Schwann cells

Question 13

A patient has a brain infection. Which neuroglia would you expect to find in increased numbers in the affected area?

Accepted Answer

Microglia

Question 14

Which of the following best describes the role of the axon hillock in a neuron?

Accepted Answer

It is the region where action potentials are initiated.

Question 15

Which of the following is a correct statement about the equilibrium potential for potassium ($$K^+) $$and sodium ($$Na^+) $$ions?

Accepted Answer

The equilibrium potential for $$K^+ is -90 mV $$and for $$Na^+ is +66 mV.$$

Question 16

Which of the following best explains why action potentials are described as 'all-or-none' events?

Accepted Answer

Any stimulus that brings the membrane to threshold will produce an identical action potential.

Question 17

Which of the following is a function of satellite cells in the PNS?

Accepted Answer

They regulate the environment around peripheral neuron cell bodies.

Question 18

A patient has a mutation that causes the sodium-potassium pump to eject only 2 $$Na^+$$ ions for every 2 $$K^+$$ ions recovered. What would be the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential would become less negative (closer to zero).

Question 19

Which of the following best describes the sequence of events at a cholinergic synapse?

Accepted Answer

Action potential arrives, voltage-gated calcium channels open, ACh is released, ACh binds to receptors, ACh is broken down by acetylcholinesterase.

Nervous Tissue: Structure, Function, and Neurophysiology

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