Question 1

Which of the following best describes the shape and nucleation of smooth muscle fibers?

Accepted Answer

Uni-nucleated and spindle-shaped

Question 2

Smooth muscle fibers are usually electrically connected via which of the following structures?

Accepted Answer

Gap junctions

Question 3

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

Accepted Answer

Calmodulin

Question 4

What is the correct ratio of thick to thin filaments in smooth muscle?

Accepted Answer

$$1:13$$

Question 5

Which layer of smooth muscle fibers runs parallel to the long axis of the organ?

Accepted Answer

Longitudinal layer

Question 6

During smooth muscle contraction, which enzyme is activated by calmodulin?

Accepted Answer

Myosin light chain kinase

Question 7

Which of the following is a major difference between smooth and skeletal muscle contraction?

Accepted Answer

Smooth muscle contraction is triggered by Ca$$^{2+}$$ binding to calmodulin

Question 8

Which structure anchors filaments in smooth muscle fibers?

Accepted Answer

Dense bodies

Question 9

What is the primary source of Ca$$^{2+}$$ for smooth muscle contraction?

Accepted Answer

Extracellular space

Question 10

Which of the following is NOT a similarity between smooth and skeletal muscle contraction?

Accepted Answer

Both use troponin to bind Ca$$^{2+}$$

Question 11

A patient is experiencing abnormal contraction of the digestive tract. Which layer of smooth muscle is most likely involved if the lumen is constricted?

Accepted Answer

Circular layer

Question 12

Which of the following best explains why smooth muscle contraction requires more steps than skeletal muscle contraction?

Accepted Answer

Smooth muscle requires activation of myosin kinase and phosphorylation of myosin

Question 13

Which of the following mechanisms is responsible for relaxation of smooth muscle?

Accepted Answer

Dephosphorylation of myosin

Question 14

Which of the following is a regulatory mechanism for smooth muscle contraction?

Accepted Answer

Both neural regulation and hormone/local chemicals

Question 15

Which connective tissue sheath is found in skeletal muscle but not in smooth muscle?

Accepted Answer

Epimysium

Question 16

Which of the following is a function of caveolae in smooth muscle cells?

Accepted Answer

Allow rapid influx of extracellular Ca$$^{2+}$$

Question 17

Which of the following best describes the arrangement of thick and thin filaments in smooth muscle?

Accepted Answer

Arranged diagonally

Question 18

Which of the following is true about varicosities in smooth muscle?

Accepted Answer

They release neurotransmitters into a wide synaptic cleft called a diffuse junction

Question 19

Which of the following is a correct step in the process of smooth muscle contraction?

Accepted Answer

Activated myosin kinase phosphorylates myosin head

Question 20

Which of the following is NOT a location where smooth muscle is typically found?

Accepted Answer

Heart

Smooth Muscle: Structure, Function, and Comparison with Skeletal Muscle

Guida di studio - Domande di pratica

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