Question 1

Which of the following correctly lists the order of structures from largest to smallest in skeletal muscle anatomy?

Accepted Answer

Muscle → fascicles → muscle fibers → myofibrils → myofilaments

Question 2

During the sliding filament model of contraction, which event occurs as the muscle contracts?

Accepted Answer

Thin filaments slide past thick filaments, causing greater overlap without changing filament length

Question 3

What is the primary function of the neurotransmitter acetylcholine (ACh) at the neuromuscular junction?

Accepted Answer

To bind to receptors on the sarcolemma and initiate an action potential

Question 4

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in muscle contraction?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) in $$response to an action potential

Question 5

Which event directly triggers the opening of voltage-gated sodium channels in the sarcolemma during muscle fiber excitation?

Accepted Answer

End plate potential reaching threshold voltage

Question 6

What is the correct sequence of events at the neuromuscular junction leading to muscle fiber excitation?

Accepted Answer

AP arrives at axon terminal → Ca$$^{2+}$$ enters axon terminal → ACh released into synaptic cleft → ACh binds to receptors

Question 7

Which of the following changes occur in the sarcomere during muscle contraction?

Accepted Answer

I bands shorten, H zones disappear, A bands move closer together

Question 8

A patient is exposed to a toxin that blocks acetylcholinesterase at the neuromuscular junction. What is the most likely effect on muscle contraction?

Accepted Answer

Muscle fibers will remain contracted due to prolonged ACh activity

Question 9

Which equation best represents the direct phosphorylation of ADP by creatine phosphate (CP) in muscle cells?

Accepted Answer

$$\mathrm{CP + ADP \rightarrow Creatine + ATP}$$

Question 10

Which of the following is TRUE regarding the refractory period in muscle fiber excitation?

Accepted Answer

The muscle fiber cannot be stimulated again until repolarization is complete

Question 11

Which type of contraction occurs when muscle tension increases but the muscle does not change length?

Accepted Answer

Isometric contraction

Question 12

What is the main role of T tubules in excitation-contraction coupling?

Accepted Answer

To transmit the action potential deep into the muscle fiber

Question 13

Which of the following best describes the process of repolarization in muscle fiber excitation?

Accepted Answer

Restoration of resting ionic and voltage conditions by opening K$$^+$$ channels

Question 14

A muscle fiber is stimulated repeatedly at high frequency, resulting in sustained contraction without relaxation. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Question 15

Which of the following factors does NOT directly increase the force of muscle contraction?

Accepted Answer

Increasing the degree of muscle stretch beyond optimal length

Question 16

Which statement about cross bridge cycling is correct?

Accepted Answer

Myosin heads bind to actin, detach, and re-cock several times during contraction

Question 17

Which of the following is a correct description of the resting membrane potential in excitable cells?

Accepted Answer

It is usually $$-70 mV $$and maintained by carrier/channel proteins such as the Na$$^+/K$^+$$ pump

Question 18

Which muscle sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 19

Which of the following best explains why action potentials cannot spread directly from one muscle cell to another?

Accepted Answer

Muscle cells are separated by the synaptic cleft and require neurotransmitter signaling

Question 20

Which of the following is TRUE regarding the role of Z discs during muscle contraction?

Accepted Answer

Z discs are pulled toward the M line and get closer together

Skeletal Muscle Tissue and Contraction: Structure and Function (Chapter 9, Human Anatomy & Physiology)

Study Guide - Practice Questions