$$3 \mathrm{Na}^+_{\text{out}} : 2 \mathrm{K}^+_{\text{in}}$$

Question 1

Which of the following best describes the correct order of muscle structure from smallest to largest?

Accepted Answer

Myofibril → muscle fiber → fascicle → muscle

Question 2

During skeletal muscle contraction, which sarcomere regions change length and why?

Accepted Answer

The I band and H zone shorten because actin and myosin filaments slide past each other.

Question 3

Which of the following best describes the role of ATP in the cross-bridge cycle during muscle contraction?

Accepted Answer

ATP binds to myosin, causing it to detach from actin.

Question 4

What prevents the cross-bridge cycle from occurring in a relaxed skeletal muscle?

Accepted Answer

Tropomyosin blocks the myosin binding sites on actin.

Question 5

A patient is unable to perform rapid, short bursts of activity such as sprinting. Which muscle fiber type is most likely deficient?

Accepted Answer

Fast-glycolytic fibers

Question 6

Which of the following best describes the difference between isometric and isotonic muscle contractions?

Accepted Answer

Isometric contractions generate tension without changing muscle length; isotonic contractions change muscle length.

Question 7

Which of the following glial cells is responsible for forming the myelin sheath in the central nervous system?

Accepted Answer

Oligodendrocytes

Question 8

At resting membrane potential, which of the following statements is correct regarding ion distribution and channel activity?

Accepted Answer

Potassium ions are more concentrated inside the cell, and most leak channels open for potassium.

Question 9

Which equation best represents the sodium-potassium pump's action in maintaining resting membrane potential?

Accepted Answer

$$3 \mathrm{Na}^+_{	ext{out}} : 2 \mathrm{K}^+_{	ext{in}}$$

Question 10

A neuron receives a stimulus that causes a graded potential. Which of the following best distinguishes a graded potential from an action potential?

Accepted Answer

Graded potentials vary in amplitude and can summate; action potentials are all-or-none.

Question 11

During an action potential, which phase is characterized by the opening of voltage-gated sodium channels?

Accepted Answer

Depolarization

Question 12

Why is the refractory period important in action potential propagation?

Accepted Answer

It ensures unidirectional propagation of the action potential.

Question 13

At a chemical synapse, which ion's influx into the presynaptic terminal triggers neurotransmitter release?

Accepted Answer

$$\mathrm{Ca}^{2+}$$

Question 14

Which of the following best describes an excitatory postsynaptic potential (EPSP)?

Accepted Answer

It is caused by the influx of $$\mathrm{Na}^+$$, making the postsynaptic membrane more likely to reach threshold.

Question 15

Which neurotransmitter is primarily released by postganglionic sympathetic neurons?

Accepted Answer

Norepinephrine

Question 16

Which brain region is primarily responsible for regulating homeostasis, including body temperature and hunger?

Accepted Answer

Hypothalamus

Question 17

Which of the following best describes the difference between white matter and gray matter in the central nervous system?

Accepted Answer

White matter consists mainly of myelinated axons; gray matter contains neuron cell bodies.

Question 18

Which of the following is an example of negative feedback in human physiology?

Accepted Answer

Regulation of blood glucose by insulin

Question 19

Which process requires energy input and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 20

Which of the following best distinguishes mitosis from meiosis?

Accepted Answer

Mitosis produces two genetically identical cells; meiosis produces four genetically unique cells.

Comprehensive Study Notes: Muscular and Nervous Systems, Homeostasis, and Cellular Foundations

Study Guide - Practice Questions