Q: Which of the following equations correctly represents the Nernst equation for calculating the equilibrium potential for an ion?

$$E = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{outside}}}{[\text{ion}]_{\text{inside}}} \right)$$

Question 1

Which of the following best describes the sequence of events during an action potential in a neuron?

Accepted Answer

Na$$ ^+ $$ channels open causing depolarization, followed by K$$ ^+ $$ channels opening causing repolarization.

Question 2

A neuron is exposed to a toxin that blocks voltage-gated K$$ ^+ $$ channels. What effect would this have on the action potential?

Accepted Answer

Repolarization would be delayed, prolonging the action potential.

Question 3

Which of the following best explains why the opening of a Cl$$ ^- $$ channel in a postsynaptic neuron typically results in an inhibitory postsynaptic potential (IPSP)?

Accepted Answer

Cl$$ ^- $$ influx hyperpolarizes the membrane, making it less likely to reach threshold.

Question 4

During the absolute refractory period of a neuron, which of the following is true?

Accepted Answer

No new action potential can be initiated, regardless of stimulus strength.

Question 5

A patient has a mutation that causes voltage-gated Na$$ ^+ $$ channels to inactivate more slowly than normal. What is the most likely effect on their action potentials?

Accepted Answer

Action potentials will be broader and last longer.

Question 6

Which of the following equations correctly represents the Nernst equation for calculating the equilibrium potential for an ion?

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 7

If a neurotransmitter causes the opening of ligand-gated Na$$ ^+ $$ channels on the postsynaptic membrane, what is the most likely result?

Accepted Answer

An excitatory postsynaptic potential (EPSP) is generated.

Question 8

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

Neuronal activity will decrease due to increased Cl$$ ^- $$ influx.

Question 9

Which of the following best describes temporal summation in a postsynaptic neuron?

Accepted Answer

Multiple EPSPs from a single presynaptic neuron occur in rapid succession.

Question 10

Which of the following is a correct statement about the propagation of an action potential along a myelinated axon?

Accepted Answer

The action potential jumps from one node of Ranvier to the next, a process called saltatory conduction.

Question 11

A patient presents with muscle weakness and is found to have a defect in acetylcholine release at the neuromuscular junction. Which of the following best explains the resulting effect on muscle contraction?

Accepted Answer

Decreased acetylcholine release leads to reduced stimulation of muscle fibers and weaker contractions.

Question 12

Which of the following best describes the role of the sodium-potassium pump ($$	ext{Na}^+/	ext{K}^+$$ ATPase) in maintaining the resting membrane potential?

Accepted Answer

It moves 3 Na$$ ^+ $$ ions out and 2 K$$ ^+ $$ ions in, maintaining a negative charge inside the cell.

Question 13

A patient is exposed to a neurotoxin that blocks voltage-gated Ca$$ ^{2+} $$ channels at the presynaptic terminal. What is the most likely effect on synaptic transmission?

Accepted Answer

Neurotransmitter release will be inhibited, reducing synaptic transmission.

Question 14

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

Accepted Answer

Myelin insulates the axon, allowing action potentials to jump between nodes of Ranvier.

Question 15

Which of the following is the correct order of events at a chemical synapse?

Accepted Answer

Action potential arrives, Ca$$ ^{2+} $$ channels open, neurotransmitter released, postsynaptic receptors activated.

Question 16

A neuron receives simultaneous EPSPs and IPSPs at different locations on its dendrites. Which of the following best describes the outcome?

Accepted Answer

The postsynaptic potential will be the algebraic sum of all EPSPs and IPSPs.

Question 17

Which of the following best describes the function of an antagonist at a neurotransmitter receptor?

Accepted Answer

It binds to the receptor and blocks the action of the neurotransmitter.

Question 18

Which of the following best explains why the resting membrane potential of a neuron is close to the equilibrium potential of K$$ ^+ $$?

Accepted Answer

The membrane is more permeable to K$$ ^+ $$ than to Na$$ ^+  at $$rest.

Question 19

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

Accepted Answer

Muscle contraction will be weakened due to faster breakdown of acetylcholine.

Question 20

Which of the following best describes the effect of opening ligand-gated K$$ ^+ $$ channels on the postsynaptic membrane?

Accepted Answer

K$$ ^+ $$ efflux hyperpolarizes the membrane, producing an IPSP.

Neurophysiology and Muscle Physiology: Study Guide Notes

Guida di studio - Domande di pratica

Study guide - Flashcard