Question 1

Which property of cardiac muscle tissue allows it to withstand stretching during ventricular filling without rupturing?

Accepted Answer

Distensibility

Question 2

A patient is unable to relax their muscles after contraction. Which protein malfunction could explain this symptom?

Accepted Answer

Titin

Question 3

Which of the following best describes the structure and function of skeletal muscle tissue?

Accepted Answer

Long, cylindrical, multinucleated cells; voluntary control; produces movement of the body

Question 4

During the excitation phase of skeletal muscle contraction, what is the role of acetylcholinesterase (AChE)?

Accepted Answer

It degrades acetylcholine in the synaptic cleft, ending the signal for muscle contraction.

Question 5

Which step in the crossbridge cycle directly requires ATP hydrolysis?

Accepted Answer

Recocking of the myosin head

Question 6

A muscle fiber is stimulated by a single action potential, resulting in a brief contraction followed by relaxation. What is this response called?

Accepted Answer

Muscle twitch

Question 7

Which type of muscle contraction occurs when the muscle length does not change, even though tension is generated?

Accepted Answer

Isometric contraction

Question 8

What is the primary immediate source of ATP for muscle contraction during the first 10 seconds of maximal activity?

Accepted Answer

Creatine phosphate reaction

Question 9

Which of the following best explains why thin filaments do not slide backward during the crossbridge cycle?

Accepted Answer

Some myosin heads remain attached to actin while others are recocked by ATP.

Question 10

A muscle is slowly lowering a heavy object. Which type of contraction is occurring, and what is the relationship between muscle force and load?

Accepted Answer

Isotonic eccentric; muscle force is less than the load

Question 11

Which of the following is true regarding the role of myoglobin in muscle fibers?

Accepted Answer

It binds oxygen and releases it during oxidative catabolism.

Question 12

Which of the following best describes the sequence of events during the excitation-contraction coupling phase?

Accepted Answer

End-plate potential stimulates an action potential, which is propagated down T-tubules, leading to calcium release from the sarcoplasmic reticulum.

Question 13

Which of the following is a function of muscle tone?

Accepted Answer

Maintains posture and stabilizes joints

Question 14

A muscle fiber is unable to pump calcium ions back into the sarcoplasmic reticulum. What is the most likely consequence?

Accepted Answer

The muscle will remain contracted (spasm).

Question 15

Which of the following equations correctly represents the creatine phosphate reaction for immediate ATP regeneration in muscle fibers?

Accepted Answer

$$\mathrm{ADP} + \mathrm{Creatine\ phosphate} \xrightarrow{CK} \mathrm{ATP} + \mathrm{Creatine}$$

Question 16

Which muscle type is characterized by striations, involuntary control, and the presence of intercalated discs?

Accepted Answer

Cardiac muscle

Question 17

Which of the following best explains why creatine supplementation is not effective for endurance athletes?

Accepted Answer

Creatine phosphate provides energy only for short bursts of maximal activity.

Question 18

Which of the following is the correct order of events in the contraction phase of the sliding-filament mechanism?

Accepted Answer

ATP hydrolysis cocks the myosin head, myosin head binds to actin, power stroke occurs, ATP detaches myosin from actin

Question 19

Which of the following best describes the role of the motor unit in muscle contraction?

Accepted Answer

It is a single motor neuron and all the muscle fibers it innervates.

Question 20

Which process provides the greatest amount of ATP for sustained muscle activity lasting several minutes to hours?

Accepted Answer

Oxidative (aerobic) catabolism

Muscle Tissue and Physiology: Structure, Function, and Contraction Mechanisms

Study Guide - Practice Questions