Question 1

Which of the following best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

Accepted Answer

It stores and releases Ca$$^{2+}$$ ions, which are essential for triggering muscle contraction.

Question 2

During the cross-bridge cycle, what is the immediate effect of ATP binding to the myosin head?

Accepted Answer

The myosin head detaches from the actin filament.

Question 3

Which connective tissue sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

What is the primary function of creatine phosphate in muscle cells?

Accepted Answer

To rapidly regenerate ATP from ADP during the initial seconds of muscle contraction.

Question 5

Which of the following statements about the sliding filament model of contraction is correct?

Accepted Answer

Thin filaments slide past thick filaments, increasing their overlap without changing the length of either filament.

Question 6

A muscle fiber is stimulated by a single action potential and produces a quick contraction followed by relaxation. This event is called:

Accepted Answer

A muscle twitch

Question 7

Which type of muscle fiber is best suited for endurance activities such as marathon running?

Accepted Answer

Slow oxidative fibers

Question 8

What is the effect of increasing the frequency of stimulation on muscle contraction?

Accepted Answer

It leads to wave summation and can result in tetanus if the frequency is high enough.

Question 9

Which of the following is TRUE regarding smooth muscle contraction compared to skeletal muscle contraction?

Accepted Answer

Smooth muscle contraction is slower and can be maintained for longer periods with less energy.

Question 10

Which protein binds Ca$$^{2+} in $$smooth muscle to initiate contraction?

Accepted Answer

Calmodulin

Question 11

A patient is unable to maintain muscle contraction despite continued stimulation. Which of the following is the most likely cause?

Accepted Answer

Muscle fatigue due to ionic imbalances and decreased ATP availability.

Question 12

Which of the following best explains the size principle of motor unit recruitment?

Accepted Answer

Smaller motor units are recruited first, followed by larger units as stimulus intensity increases.

Question 13

What is the main difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions result in muscle shortening, while isometric contractions do not change muscle length.

Question 14

Which of the following events occurs FIRST during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential is propagated along the sarcolemma and down T tubules.

Question 15

Which of the following is a function of muscle tone?

Accepted Answer

Keeps muscles firm, healthy, and ready to respond to stimulation.

Question 16

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

Accepted Answer

Ability to synthesize creatine phosphate.

Question 17

Which of the following best describes the role of the Z disc in a sarcomere?

Accepted Answer

It anchors thin filaments and defines the boundaries of a sarcomere.

Question 18

Which of the following is TRUE regarding the energy systems used during different types of exercise?

Accepted Answer

Aerobic respiration is the primary source of ATP during prolonged, light-to-moderate exercise.

Question 19

Which of the following is a unique feature of smooth muscle compared to skeletal muscle?

Accepted Answer

Smooth muscle cells are connected by gap junctions and can contract in a corkscrew motion.

Question 20

Which equation correctly represents the direct phosphorylation of ADP by creatine phosphate in muscle cells?

Accepted Answer

$$	ext{Creatine~phosphate} + 	ext{ADP} \xrightarrow{	ext{creatine~kinase}} 	ext{Creatine} + 	ext{ATP}$$

Comprehensive Study Notes on Muscle Tissue and Contraction Mechanisms

Study Guide - Practice Questions