Question 1

Which connective tissue layer directly surrounds individual muscle fibers within a skeletal muscle?

Accepted Answer

Endomysium

Question 2

During the contraction of a skeletal muscle fiber, which of the following changes occur according to the sliding-filament theory?

Accepted Answer

The Z lines move closer together

Question 3

What is the primary function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

Storing and releasing calcium ions

Question 4

A patient presents with muscle weakness and a biopsy reveals a lack of myoglobin in their muscle fibers. Which type of muscle fiber is most likely deficient?

Accepted Answer

Slow fibers

Question 5

Which of the following best describes the role of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine in the synaptic cleft

Question 6

Which of the following equations correctly represents the reaction catalyzed by creatine kinase during muscle contraction?

Accepted Answer

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

Question 7

A muscle is stimulated repeatedly at a frequency just below 50 stimuli per second, resulting in a stair-step increase in tension. What is this phenomenon called?

Accepted Answer

Treppe

Question 8

Which of the following is true regarding isometric muscle contractions?

Accepted Answer

The muscle develops tension but does not change length

Question 9

Which protein binds calcium ions to initiate the exposure of active sites on actin during skeletal muscle contraction?

Accepted Answer

Troponin

Question 10

A patient is unable to relax their muscles after death, resulting in a fixed muscular contraction. What is the physiological cause of this condition?

Accepted Answer

Lack of ATP and accumulation of calcium ions in the cytosol

Question 11

Which of the following best explains why cardiac muscle cannot undergo tetanic contractions?

Accepted Answer

Cardiac muscle has a long refractory period that prevents wave summation

Question 12

Which of the following statements about smooth muscle is correct?

Accepted Answer

Smooth muscle contraction is triggered by calcium binding to calmodulin

Question 13

During moderate activity, which metabolic pathway is the primary source of ATP for skeletal muscle fibers?

Accepted Answer

Aerobic metabolism of glucose

Question 14

Which of the following best describes the function of intercalated discs in cardiac muscle tissue?

Accepted Answer

They allow ions to move between cells, enabling coordinated contraction

Question 15

A muscle fiber is stimulated while at a sarcomere length that produces minimal overlap between thick and thin filaments. What is the expected outcome for tension production?

Accepted Answer

Minimal tension is produced due to few cross-bridges forming

Question 16

Which of the following hormones does NOT directly increase metabolic activity in skeletal muscle?

Accepted Answer

Insulin

Question 17

Which of the following is a characteristic of fast muscle fibers?

Accepted Answer

Few mitochondria and rapid fatigue

Question 18

Which of the following best describes the process of muscle hypertrophy?

Accepted Answer

Increase in the diameter of muscle fibers and number of myofibrils

Question 19

Which of the following is the correct sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential → ACh release → Ca2+ release from SR → Cross-bridge formation

Question 20

A muscle is producing tension but is not changing length. Which type of contraction is occurring, and what is the relationship between muscle tension and load?

Accepted Answer

Isometric contraction; muscle tension does not exceed load

Muscle Tissue: Structure and Organization

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