Q: Which equation best represents the Nernst equation for calculating the equilibrium potential for a single 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 relative concentrations of sodium (Na⁺) and potassium (K⁺) ions inside and outside a typical skeletal muscle fiber at rest?

Accepted Answer

Higher Na⁺ outside the cell, higher K⁺ inside the cell

Question 2

A concentration gradient refers to:

Accepted Answer

The difference in the concentration of a substance between two regions

Question 3

Which equation best represents the Nernst equation for calculating the equilibrium potential for a single ion?

Accepted Answer

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

Question 4

Which of the following best describes an electrochemical gradient?

Accepted Answer

A gradient that combines both the concentration difference and the electrical charge difference across a membrane

Question 5

The resting membrane potential of a skeletal muscle fiber is primarily established by:

Accepted Answer

The active transport of Na⁺ and passive diffusion of K⁺

Question 6

During the depolarization phase of a skeletal muscle fiber action potential, which event occurs?

Accepted Answer

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

Question 7

Which of the following best explains why the inside of a resting skeletal muscle fiber is negatively charged relative to the outside?

Accepted Answer

There are more negatively charged proteins and a higher permeability to K⁺ than Na⁺

Question 8

Which sequence correctly describes the events of a skeletal muscle fiber action potential?

Accepted Answer

Depolarization, repolarization, hyperpolarization, return to resting potential

Question 9

If the Na⁺/K⁺ ATPase pump is inhibited in a skeletal muscle fiber, what is the most likely immediate effect?

Accepted Answer

The resting membrane potential becomes less negative

Question 10

A patient is given a drug that increases the permeability of the muscle cell membrane to Na⁺ at rest. What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential will become less negative (depolarize)

Question 11

Which of the following is a key difference between a concentration gradient and an electrochemical gradient?

Accepted Answer

A concentration gradient involves only the difference in ion concentration, while an electrochemical gradient includes both concentration and electrical charge differences

Question 12

Which of the following best describes the role of voltage-gated K⁺ channels during the action potential of a skeletal muscle fiber?

Accepted Answer

They open during repolarization to allow K⁺ to exit the cell

Question 13

Which of the following is the best example of a real-life scenario involving the disruption of the resting membrane potential in skeletal muscle fibers?

Accepted Answer

Hyperkalemia (elevated blood K⁺) causing muscle weakness due to depolarization of the resting membrane potential

Question 14

Which of the following best explains why the Na⁺/K⁺ ATPase pump is considered electrogenic?

Accepted Answer

It moves 3 Na⁺ out for every 2 K⁺ in, creating a net negative charge inside the cell

Question 15

During which phase of the action potential are voltage-gated Na⁺ channels inactivated and voltage-gated K⁺ channels open?

Accepted Answer

Repolarization

Skeletal Muscle Fibers as Electrically Excitable Cells

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