Q: Which of the following equations correctly represents the reaction catalyzed by creatine kinase during immediate energy production in muscle fibers?

$$\mathrm{ADP} + \mathrm{CP} \xrightarrow{\text{creatine kinase}} \mathrm{ATP} + \mathrm{Creatine}$$

Question 1

Which of the following best describes the role of the endomysium in skeletal muscle tissue?

Accepted Answer

It transmits tension generated by muscle cells to neighboring cells and holds muscle cells together.

Question 2

A patient presents with muscle weakness and a waddling gait. Genetic testing reveals a mutation in the gene encoding dystrophin. Which of the following best explains the role of dystrophin in muscle fibers?

Accepted Answer

Dystrophin is a structural protein that stabilizes the sarcolemma and links the cytoskeleton to the extracellular matrix.

Question 3

Which of the following statements about the sarcomere during muscle contraction is correct?

Accepted Answer

The I band and H zone narrow, but the A band remains unchanged.

Question 4

A toxin blocks voltage-gated sodium channels in the sarcolemma of skeletal muscle fibers. What is the most immediate effect on muscle contraction?

Accepted Answer

Calcium cannot be released from the sarcoplasmic reticulum.

Question 5

Which of the following best explains why potassium ions have a greater influence on the resting membrane potential than sodium ions?

Accepted Answer

Potassium ions diffuse through leak channels more easily than sodium ions, leading to a net loss of positive charge from the cytosol.

Question 6

During the crossbridge cycle, what is the role of ATP in muscle contraction?

Accepted Answer

ATP hydrolysis cocks the myosin head and ATP binding breaks the attachment of myosin to actin.

Question 7

A patient is diagnosed with myasthenia gravis, a disease that destroys acetylcholine receptors on the motor end plate. Which of the following symptoms would you expect?

Accepted Answer

Progressive muscle weakness and paralysis.

Question 8

Which of the following equations correctly represents the reaction catalyzed by creatine kinase during immediate energy production in muscle fibers?

Accepted Answer

$$\mathrm{ADP} + \mathrm{CP} \xrightarrow{	ext{creatine kinase}} \mathrm{ATP} + \mathrm{Creatine}$$

Question 9

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

Accepted Answer

Isotonic concentric contractions shorten the muscle, while isotonic eccentric contractions lengthen the muscle under tension.

Question 10

A muscle fiber is stimulated so frequently that it does not have time to relax between stimuli, resulting in a sustained maximal contraction. What is this phenomenon called?

Accepted Answer

Fused tetanus

Question 11

Which of the following is a property shared by all muscle cells that allows them to return to their original shape after being stretched?

Accepted Answer

Elasticity

Question 12

Which of the following best explains why oxidative (aerobic) catabolism is preferred for long-duration muscle activity?

Accepted Answer

It produces more ATP per glucose molecule than glycolysis.

Question 13

Which of the following is true regarding the role of calcium ions in skeletal muscle contraction?

Accepted Answer

Calcium ions bind to troponin, causing tropomyosin to move and expose actin's active sites.

Question 14

A muscle is unable to relax after contraction and remains in a state of spasm. Which of the following is a possible cause?

Accepted Answer

Failure of calcium ion pumps in the sarcoplasmic reticulum.

Question 15

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

Accepted Answer

It binds and stores oxygen for use during aerobic metabolism.

Question 16

Which of the following best explains the principle of myoplasticity in skeletal muscle?

Accepted Answer

Muscle fibers alter their structure and biochemistry in response to changes in function and use.

Question 17

Which of the following is a correct description of the sodium-potassium pump in skeletal muscle fibers?

Accepted Answer

It moves 3 sodium ions out of the cell and 2 potassium ions in, using ATP hydrolysis.

Question 18

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

Accepted Answer

They unite cardiac muscle cells and permit coordinated contraction via gap junctions.

Question 19

A marathon runner undergoes endurance training. Which of the following adaptations would you expect in their skeletal muscle fibers?

Accepted Answer

Increased mitochondrial proteins and enhanced oxidative capacity.

Question 20

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

Accepted Answer

Regulating the flow of materials through hollow organs by changing the diameter of passages.

Chapter 10: Muscle Tissue and Physiology – Structured Study Notes

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