$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} \rightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + \text{ATP}$$

Question 1

Which of the following adaptations is most likely to occur in skeletal muscle fibers after prolonged aerobic (endurance) exercise?

Accepted Answer

Increase in the number of mitochondria

Question 2

Resistance exercise, such as weightlifting, primarily leads to which of the following changes in skeletal muscle?

Accepted Answer

Muscle fiber hypertrophy

Question 3

Which equation best represents the process of aerobic respiration in muscle cells?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} ightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + 	ext{ATP}$$

Question 4

A patient is immobilized due to injury and experiences rapid muscle atrophy. Which process is most responsible for the loss of muscle mass?

Accepted Answer

Denervation or loss of neural stimulation

Question 5

Which structural feature is unique to smooth muscle fibers compared to skeletal muscle fibers?

Accepted Answer

Spindle-shaped fibers with no striations

Question 6

Which layer of smooth muscle fibers is responsible for shortening the organ when it contracts?

Accepted Answer

Longitudinal layer

Question 7

What is the primary neurotransmitter that can stimulate or inhibit smooth muscle contraction depending on the receptor type?

Accepted Answer

Acetylcholine

Question 8

Which of the following best describes the mechanism of smooth muscle contraction?

Accepted Answer

Ca$$^{2+}$$ binds to calmodulin, activating myosin light chain kinase

Question 9

Which of the following is a key difference between single-unit (unitary) and multiunit smooth muscle?

Accepted Answer

Single-unit smooth muscle fibers are electrically coupled by gap junctions

Question 10

During prolonged inactivity, muscle strength can decline by approximately what percentage per day?

Accepted Answer

5%

Question 11

Which of the following is true regarding the arrangement of filaments in smooth muscle?

Accepted Answer

Thick and thin filaments are arranged diagonally, causing a corkscrew contraction

Question 12

Which process is required for smooth muscle relaxation after contraction?

Accepted Answer

Active transport of Ca$$^{2+}$$ into the SR and extracellular space

Question 13

Which of the following best explains why smooth muscle can maintain contraction for prolonged periods with minimal energy expenditure?

Accepted Answer

Latch state allows actin-myosin crossbridges to remain attached

Question 14

Which chemical messenger can cause either contraction or relaxation of smooth muscle depending on the receptor type present?

Accepted Answer

Norepinephrine

Question 15

Which of the following is a real-life example of the stress-relaxation response in smooth muscle?

Accepted Answer

The bladder temporarily stretching to accommodate increased urine volume

Question 16

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

Accepted Answer

Calmodulin

Question 17

Which of the following is NOT a characteristic of multiunit smooth muscle?

Accepted Answer

Fibers are electrically coupled by gap junctions

Question 18

Which of the following best describes the role of dense bodies in smooth muscle?

Accepted Answer

Anchor thin filaments to the sarcolemma

Question 19

Which of the following is a plausible consequence of muscle atrophy due to prolonged inactivity?

Accepted Answer

Replacement of lost muscle tissue by connective tissue

Question 20

Which of the following best explains why smooth muscle can contract when stretched between half and twice its resting length?

Accepted Answer

The arrangement of filaments allows for large changes in length without loss of contractile ability

Muscle Physiology: Exercise, Health, and Smooth Muscle Structure

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