Human Anatomy and Physiology : Help with General Muscle Structures

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

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Example Question #11 : Muscle Physiology

Which of the following are characteristics of only skeletal muscle?

Possible Answers:

Troponin-tropomyosin complex regulates contraction

Striated

Calcium required for contraction

Multinucleated

Correct answer:

Multinucleated

Explanation:

Characteristics of smooth muscle include: striated, somatic innervation, multinucleated, and requiring calcium for contraction. Furthermore, similar characteristics are seen in cardiac muscle such as: striations, autonomic innervation, 1-2 nuclei, requires calcium for contraction. Finally, smooth muscle is nonstriated, has autonomic innervation, mononucleated, and requiring calcium for contraction.

Example Question #11 : Muscle Physiology

To which of the following molecules does calcium released from the sarcoplasmic reticulum bind?

Possible Answers:

Myosin

Actin

Troponin

Tropomyosin

Correct answer:

Troponin

Explanation:

Calcium is released from the sarcoplasmic reticulum into the the sarcoplasm. It binds the troponin molecules on the thin filaments, causing the strands of tropomyosin to shift, exposing the myosin-binding sites on the thin filaments. 

Example Question #13 : Muscle Physiology

Where is calcium stored in the skeletal muscle cell?

Possible Answers:

Calcium is not particularly stored in any location in the skeletal muscle cell, and is equally distributed.

Calcium is stored in the sarcoplasmic reticulum, awaiting a signal for release into the cytoplasm.

Calcium is stored in the cytoplasm, awaiting a signal for release into the cytoplasm.

None of the answers are correct.

Calcium is stored extracellularly, and only allowed into the skeletal muscle cell after neuronal signals.

Correct answer:

Calcium is stored in the sarcoplasmic reticulum, awaiting a signal for release into the cytoplasm.

Explanation:

Calcium is stored in the sarcoplasmic reticulum at high concentrations. When neurons signal the contraction of muscle, calcium is released from the sarcoplasmic reticulum, and facilitates the contraction of muscle fibers and ATP hydrolysis, to generate muscle contraction force.

Example Question #11 : Muscle Physiology

The perimysium surrounds which of the following parts of a skeletal muscle fiber?

Possible Answers:

myofilament

fascicle

myofibril

myofiber

muscle

Correct answer:

fascicle

Explanation:

The perimysium surrounds the fascicles in a skeletal muscle fiber. From largest to smallest, the sequence goes as follows: the Epimysium surrounds the entire muscle; the Perimysium surrounds the fascicles inside the muscle; the Endomysium surrounds the myofiber (muscle cell).

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