Question 1

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

Accepted Answer

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

Question 2

A patient presents with muscle weakness and elevated levels of creatine kinase (CK) in the blood. Which of the following best explains the significance of elevated CK?

Accepted Answer

It indicates muscle damage, as CK leaks into the blood when muscle fibers are injured.

Question 3

During the sliding filament mechanism of muscle contraction, which of the following changes occur in the sarcomere?

Accepted Answer

The I band and H zone decrease in size, while the A band remains constant.

Question 4

Which of the following best describes the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions change muscle length and move a load, while isometric contractions increase tension without changing muscle length.

Question 5

A muscle fiber is unable to relax after contraction, resulting in a state similar to rigor mortis. Which of the following best explains this phenomenon?

Accepted Answer

There is no ATP available to detach myosin heads from actin.

Question 6

Which of the following is a characteristic unique to cardiac muscle tissue?

Accepted Answer

Presence of intercalated discs containing desmosomes and gap junctions.

Question 7

Which of the following best describes the role of troponin in muscle contraction?

Accepted Answer

It binds calcium ions, causing tropomyosin to move and expose myosin binding sites on actin.

Question 8

A marathon runner relies primarily on which metabolic pathway for ATP production during the majority of the race?

Accepted Answer

Aerobic respiration in mitochondria, producing $$32$$ ATP per glucose molecule.

Question 9

Which of the following best explains why muscle tone is important for posture?

Accepted Answer

It maintains a constant, slight contraction in muscles, keeping them firm and ready to respond to stimuli.

Question 10

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

Accepted Answer

Release of acetylcholine (ACh) from the motor neuron into the synaptic cleft.

Question 11

A patient with paralysis due to nerve injury experiences rapid muscle atrophy. Which of the following best explains this phenomenon?

Accepted Answer

Lack of neural stimulation leads to degeneration and loss of muscle mass.

Question 12

Which of the following best describes the function of the sodium-potassium ATPase pump in muscle fibers?

Accepted Answer

It maintains the resting membrane potential by pumping $$3\ \mathrm{Na^+}$$ out and $$2\ \mathrm{K^+} in $$per ATP hydrolyzed.

Question 13

Which of the following is true regarding the arrangement of connective tissue sheaths in skeletal muscle?

Accepted Answer

The epimysium surrounds the entire muscle, the perimysium surrounds fascicles, and the endomysium surrounds individual muscle fibers.

Question 14

Which of the following best explains why lactic acid accumulates in muscle during intense exercise?

Accepted Answer

Oxygen is limited, so pyruvic acid from glycolysis is converted to lactic acid.

Question 15

Which of the following is a correct sequence of events in the crossbridge cycle during muscle contraction?

Accepted Answer

Attachment of myosin to actin, pivot (power stroke), detachment upon ATP binding, return to cocked position after ATP hydrolysis.

Question 16

Which of the following best describes the function of myoglobin in muscle fibers?

Accepted Answer

It stores oxygen for use during aerobic respiration.

Question 17

A person is unable to perform fine motor movements with their fingers. Which of the following best explains this deficit?

Accepted Answer

The muscles controlling fine movements have small motor units, and damage to these units impairs precision.

Question 18

Which of the following best explains why aerobic exercise increases muscle endurance?

Accepted Answer

It increases the number of mitochondria, capillaries, and myoglobin in muscle fibers.

Question 19

Which of the following is a function of smooth muscle tissue?

Accepted Answer

Regulating the diameter of blood vessels and moving contents through hollow organs.

Question 20

Which of the following best describes the process of summation in muscle contraction?

Accepted Answer

Frequently delivered stimuli increase contractile force because the muscle does not have time to relax between stimuli.

Chapter 9: Muscles and Muscle Tissue - Study Guide

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드