BIOL251 MODULE 4: MUSCULAR
SYSTEM COMPREHENSIVE REVIEW | 50
QUESTIONS | PORTAGE LEARNING
1. Which of the following is a characteristic unique to cardiac muscle tissue compared to
skeletal muscle?
A. Intercalated discs
B. Presence of striations
C. Multinucleated cells
D. Voluntary control
Answer: A
Conceptual Explanation: Intercalated discs are specialized junctions between cardiac
muscle cells that contain gap junctions and desmosomes, allowing for synchronized
contraction. Skeletal muscle is multinucleated and voluntary.
2. The connective tissue layer that surrounds an entire muscle is known as the:
A. Perimysium
B. Endomysium
,C. Epimysium
D. Sarcolemma
Answer: C
Conceptual Explanation: The epimysium is the outermost layer of dense irregular
connective tissue that encircles the entire muscle unit.
3. What is the functional unit of a skeletal muscle fiber?
A. T-tubule
B. Myofibril
C. Sarcoplasmic reticulum
D. Sarcomere
Answer: D
Conceptual Explanation: The sarcomere is the basic functional unit of a myofibril,
extending from one Z-disc to the next.
4. During muscle contraction, which of the following shorten?
A. H-zone and I-band
B. Myosin filaments
C. A-band
D. Actin filaments
, Answer: A
Conceptual Explanation: According to the sliding filament theory, the H-zone and I-band
shorten as actin slides over myosin, but the A-band remains constant in length.
5. What is the role of Calcium ions in the sliding filament mechanism?
A. To bind to myosin heads to activate the power stroke
B. To stabilize the Z-discs during contraction
C. To hydrolyze ATP into ADP and Phosphate
D. To bind to troponin, causing tropomyosin to move off the binding sites
Answer: D
Conceptual Explanation: Calcium binds to troponin, which induces a conformational
change in tropomyosin, exposing the active sites on actin for myosin binding.
6. Which neurotransmitter is released at the neuromuscular junction to initiate contraction?
A. Dopamine
B. Norepinephrine
C. Acetylcholine
D. Serotonin
Answer: C
SYSTEM COMPREHENSIVE REVIEW | 50
QUESTIONS | PORTAGE LEARNING
1. Which of the following is a characteristic unique to cardiac muscle tissue compared to
skeletal muscle?
A. Intercalated discs
B. Presence of striations
C. Multinucleated cells
D. Voluntary control
Answer: A
Conceptual Explanation: Intercalated discs are specialized junctions between cardiac
muscle cells that contain gap junctions and desmosomes, allowing for synchronized
contraction. Skeletal muscle is multinucleated and voluntary.
2. The connective tissue layer that surrounds an entire muscle is known as the:
A. Perimysium
B. Endomysium
,C. Epimysium
D. Sarcolemma
Answer: C
Conceptual Explanation: The epimysium is the outermost layer of dense irregular
connective tissue that encircles the entire muscle unit.
3. What is the functional unit of a skeletal muscle fiber?
A. T-tubule
B. Myofibril
C. Sarcoplasmic reticulum
D. Sarcomere
Answer: D
Conceptual Explanation: The sarcomere is the basic functional unit of a myofibril,
extending from one Z-disc to the next.
4. During muscle contraction, which of the following shorten?
A. H-zone and I-band
B. Myosin filaments
C. A-band
D. Actin filaments
, Answer: A
Conceptual Explanation: According to the sliding filament theory, the H-zone and I-band
shorten as actin slides over myosin, but the A-band remains constant in length.
5. What is the role of Calcium ions in the sliding filament mechanism?
A. To bind to myosin heads to activate the power stroke
B. To stabilize the Z-discs during contraction
C. To hydrolyze ATP into ADP and Phosphate
D. To bind to troponin, causing tropomyosin to move off the binding sites
Answer: D
Conceptual Explanation: Calcium binds to troponin, which induces a conformational
change in tropomyosin, exposing the active sites on actin for myosin binding.
6. Which neurotransmitter is released at the neuromuscular junction to initiate contraction?
A. Dopamine
B. Norepinephrine
C. Acetylcholine
D. Serotonin
Answer: C
