$$\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P_i} + \text{energy}$$

Question 1

Which of the following best describes the primary function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) to $$regulate muscle contraction.

Question 2

During the sliding filament model of contraction, which event directly causes the shortening of the sarcomere?

Accepted Answer

The thin filaments slide past the thick filaments, increasing their overlap.

Question 3

Which connective tissue sheath surrounds an individual muscle fiber?

Accepted Answer

Endomysium

Question 4

A patient presents with muscle rigidity several hours after death. Which mechanism best explains this phenomenon?

Accepted Answer

ATP is no longer synthesized, preventing cross bridge detachment and causing rigor mortis.

Question 5

Which of the following is NOT a characteristic shared by all muscle tissue types?

Accepted Answer

Ability to be consciously controlled

Question 6

What is the role of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It degrades acetylcholine, terminating the signal for muscle contraction.

Question 7

Which statement correctly describes the arrangement of myofilaments within a sarcomere?

Accepted Answer

Thin (actin) filaments are anchored to the Z discs, while thick (myosin) filaments are anchored to the M line.

Question 8

Which equation best represents the relationship between ATP hydrolysis and the cocking of the myosin head during cross bridge cycling?

Accepted Answer

$$\mathrm{ATP} ightarrow \mathrm{ADP} + \mathrm{P_i} + 	ext{energy}$$

Question 9

Which muscle tissue type is found in the walls of hollow organs and is characterized by single, spindle-shaped, uninucleate cells with no striations?

Accepted Answer

Smooth muscle

Question 10

During muscle fiber excitation, what is the primary cause of depolarization?

Accepted Answer

Entry of $$\mathrm{Na^+}$$ ions through chemically gated channels

Question 11

Which of the following best describes the function of titin in the sarcomere?

Accepted Answer

It holds thick filaments in place and helps the muscle recoil after stretch.

Question 12

A muscle fiber is stimulated by a motor neuron. Which sequence correctly describes the events leading to contraction?

Accepted Answer

AP arrives at axon terminal → ACh released → ACh binds to sarcolemma → Na+ enters → AP generated → Ca2+ released → Cross bridge cycling

Question 13

Which of the following is a function of skeletal muscle that is NOT shared by smooth or cardiac muscle?

Accepted Answer

Voluntary control of contraction

Question 14

Which structure increases the surface area of the muscle fiber and allows electrical impulses to penetrate deep into the cell?

Accepted Answer

T tubules

Question 15

Which regulatory proteins are bound to actin and play a role in muscle contraction?

Accepted Answer

Troponin and tropomyosin

Question 16

If a muscle fiber is unable to repolarize after an action potential, which ion channel is most likely malfunctioning?

Accepted Answer

Voltage-gated $$\mathrm{K^+}$$ channel

Question 17

Which of the following best explains why cardiac muscle cannot be consciously controlled?

Accepted Answer

It is regulated by its own pacemaker and the autonomic nervous system.

Question 18

Which of the following is true regarding the molecular composition of thick filaments?

Accepted Answer

They are composed of myosin molecules with globular heads that form cross bridges with actin.

Question 19

Which step in the cross bridge cycle requires ATP binding to myosin?

Accepted Answer

Cross bridge detachment

Muscle Tissue: Structure, Function, and Mechanisms

Study Guide - Practice Questions