Figure 7-1 Structural Components of a Skeletal Muscle Fiber
Use Figure 7-1 to identify the labeled part.
-Structure I is composed of
A) actin and perimysium.
B) actin and myosin.
C) troponin and tropomyosin.
D) only myosin heads.
E) acetylcholine and cholinesterase.

Question

Figure 7-1 Structural Components of a Skeletal Muscle Fiber
Use Figure 7-1 to identify the labeled part.
-Structure I is composed of
A) actin and perimysium. 
B) actin and myosin. 
C) troponin and tropomyosin. 
D) only myosin heads. 
E) acetylcholine and cholinesterase.

Quizplus · Accepted Answer

Structure I is the myofibril, which is composed of actin and myosin. Troponin and tropomyosin are regulatory proteins associated with actin, while perimysium is connective tissue that surrounds bundles of muscle fibers.