Question 1

Which of the following best describes the function of the sodium-potassium pump in establishing the resting membrane potential of a neuron?

Accepted Answer

It pumps three sodium ions out of the cell and two potassium ions into the cell, creating a net negative charge inside the cell.

Question 2

A neuron receives multiple excitatory postsynaptic potentials (EPSPs) from different presynaptic neurons at the same time. What is this process called, and what is its effect?

Accepted Answer

Spatial summation; it increases the likelihood of reaching threshold for an action potential.

Question 3

Which of the following equations correctly represents the Nernst equation for calculating the equilibrium potential ($$E_{ion}) $$for a monovalent cation?

Accepted Answer

$$E_{ion} = \frac{61}{z} \log \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 4

During the absolute refractory period of an action potential, why is it impossible for another action potential to be generated?

Accepted Answer

The inactivation gates of voltage-gated sodium channels are closed, preventing Na+ influx.

Question 5

A patient is given a drug that blocks voltage-gated potassium channels. What effect would this have on the action potential?

Accepted Answer

It would prolong repolarization, causing the action potential to last longer.

Question 6

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

Accepted Answer

Myelin allows action potentials to jump between nodes of Ranvier in a process called saltatory conduction.

Question 7

If a neurotransmitter opens ligand-gated chloride channels on the postsynaptic membrane, what is the likely effect on the postsynaptic cell?

Accepted Answer

It will hyperpolarize the cell, making it less likely to fire an action potential.

Question 8

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

Accepted Answer

They decay over distance and time.

Question 9

A neuron is exposed to a toxin that increases the permeability of the membrane to potassium ions. What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential will become more negative (hyperpolarized).

Question 10

Which of the following best describes the process of synaptic transmission at a chemical synapse?

Accepted Answer

Neurotransmitter is released from the presynaptic terminal, crosses the synaptic cleft, and binds to receptors on the postsynaptic membrane.

Question 11

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

Accepted Answer

Opening of potassium or chloride channels on the postsynaptic membrane.

Question 12

A neuron is at rest with a membrane potential of $$-70\ \mathrm{mV}. If $$the equilibrium potential for potassium ($$E_K) is$$ $$-90\ \mathrm{mV}$$ and for sodium ($$E_{Na}) is$$ $$+62\ \mathrm{mV}$$, which statement is correct?

Accepted Answer

The membrane is more permeable to potassium than sodium at rest.

Question 13

Which of the following mechanisms is NOT a way to terminate neurotransmitter action in the synaptic cleft?

Accepted Answer

Continuous release of neurotransmitter from the postsynaptic cell.

Question 14

A patient is given a drug that acts as an agonist at GABA receptors. What is the most likely effect on neuronal activity?

Accepted Answer

Decreased likelihood of action potential firing due to hyperpolarization.

Question 15

Which of the following best explains the 'all-or-nothing' nature of the action potential?

Accepted Answer

Once threshold is reached, an action potential of fixed size and duration is generated.

Question 16

Which of the following is a real-life example of a mechanically-gated ion channel in action?

Accepted Answer

A touch receptor in the skin opening channels in response to pressure.

Question 17

If a neuron is exposed to a drug that blocks acetylcholinesterase, what is the most likely effect at the neuromuscular junction?

Accepted Answer

Acetylcholine will remain in the synaptic cleft longer, leading to prolonged muscle contraction.

Question 18

Which of the following best describes the effect of temporal summation on the postsynaptic membrane?

Accepted Answer

A single presynaptic neuron fires repeatedly, causing neurotransmitter to build up and produce a stronger graded potential.

Question 19

A patient is given a drug that blocks the reuptake of serotonin in the brain. What is the most likely effect?

Accepted Answer

Increased serotonin levels in the synaptic cleft, enhancing neurotransmission.

Nervous Tissue Physiology: Structure, Function, and Signal Transmission

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