Q: Which equation best represents the action of the sodium-potassium pump?

$$3\ \mathrm{Na}^+_{\text{in}} + 2\ \mathrm{K}^+_{\text{out}} + \mathrm{ATP} \rightarrow 3\ \mathrm{Na}^+_{\text{out}} + 2\ \mathrm{K}^+_{\text{in}} + \mathrm{ADP} + \mathrm{P}_i$$

Question 1

Which of the following best describes the function of the sodium-potassium pump in maintaining the resting membrane potential (RMP) of a neuron?

Accepted Answer

It actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell using ATP.

Question 2

During the depolarization phase of an action potential, which of the following occurs?

Accepted Answer

Voltage-gated Na+ channels open, allowing Na+ to enter the cell.

Question 3

What is the primary reason the inside of a neuron is more negatively charged than the outside at rest?

Accepted Answer

There are more negatively charged anions (proteins, phosphates) inside the cell.

Question 4

Which equation best represents the action of the sodium-potassium pump?

Accepted Answer

$$3\ \mathrm{Na}^+_{	ext{in}} + 2\ \mathrm{K}^+_{	ext{out}} + \mathrm{ATP} ightarrow 3\ \mathrm{Na}^+_{	ext{out}} + 2\ \mathrm{K}^+_{	ext{in}} + \mathrm{ADP} + \mathrm{P}_i$$

Question 5

A patient with multiple sclerosis (MS) is likely to experience which of the following changes in nerve conduction?

Accepted Answer

Slower nerve conduction due to loss of myelin sheaths.

Question 6

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

Accepted Answer

The refractory period prevents the area behind the action potential from being re-excited immediately.

Question 7

Which of the following is true regarding saltatory conduction in myelinated axons?

Accepted Answer

Action potentials jump from one node of Ranvier to the next.

Question 8

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

Accepted Answer

Voltage-gated K+ channels open and K+ exits the cell.

Question 9

A neuron is exposed to a toxin that blocks voltage-gated Na+ channels. What is the most likely effect on nerve signaling?

Accepted Answer

The neuron will be unable to generate an action potential.

Question 10

Which of the following best describes the difference between ligand-gated and voltage-gated ion channels?

Accepted Answer

Ligand-gated channels open in response to neurotransmitter binding, while voltage-gated channels open in response to changes in membrane voltage.

Question 11

Which of the following best explains why the resting membrane potential is typically around $$-70\ \mathrm{mV}$$?

Accepted Answer

There is a greater permeability to K+ than Na+, and negatively charged proteins are trapped inside the cell.

Question 12

A patient is given a drug that increases the activity of acetylcholinesterase at synapses. What is the most likely effect?

Accepted Answer

Decreased duration of acetylcholine action at the synapse.

Question 13

Which of the following is a direct consequence of the refractory period in neurons?

Accepted Answer

Action potentials cannot travel backward along the axon.

Question 14

Which of the following best describes the effect of dopamine loss in Parkinson’s disease?

Accepted Answer

Loss of inhibition in motor pathways, resulting in involuntary muscle contractions.

Question 15

Which of the following is true about the propagation of action potentials in unmyelinated axons?

Accepted Answer

Action potentials are generated at every point along the axon.

Question 16

A neuron is exposed to a drug that blocks the reuptake of neurotransmitters at the synaptic cleft. What is the most likely effect?

Accepted Answer

Neurotransmitter concentration in the synaptic cleft will remain elevated, prolonging the signal.

Question 17

Which of the following best describes the role of the nodes of Ranvier in myelinated axons?

Accepted Answer

They are gaps in the myelin sheath where action potentials are regenerated.

Question 18

Which of the following scenarios would most likely result in hyperpolarization of a neuron?

Accepted Answer

Opening of additional K+ channels, allowing more K+ to exit the cell.

Question 19

A patient presents with muscle weakness and visual disturbances. MRI reveals demyelination in the CNS. Which disease is most likely?

Accepted Answer

Multiple sclerosis

Nervous System: Membrane Potentials, Nerve Signaling, and Synaptic Transmission

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