Question

The structural and functional unit of the striated muscle fiber is called as
a. Sarcolemma
b. Sarcomere
c. Sarcoplasm
d. Myofibril

Answer 1

Hint: In animals, there are mainly two types of muscles are found, they are striated and unstriated muscles, there are mainly two muscles, that come under striated muscles are cardiac and skeletal muscles, where they have a striated appearance.

Complete answer:
- The structural and functional unit of muscle fiber is the sarcomere.
- Each myofiber again consists of actin and myosin molecules which help in the muscle contraction.
- Each muscle fiber contains sarcolemma, and the sarcoplasm as well as the sarcoplasmic reticulum.
- These muscle fibers are encased in the collagen and form the fascicles and they also consist of endomysium.
- The whole muscle structure is usually wrapped in a layer called epimysium.
- Cardiac muscle fibers usually contain only one nucleus, and they are interconnected to each other by intercalated discs.
- Every skeletal muscle fiber is supplied by the blood for rich nutrition and oxygen supply and it is also supplied by the axon of the somatic neuron, Whereas in the cardiac muscle and smooth muscle, the only way for the muscle to contract is to get the signal from the nerves.
- When coming to the terminology of the muscle fiber, the plasma membrane of the muscle fiber is called as sarcolemma, and the cytoplasm of the muscle fiber as sarcoplasm, whereas the endoplasmic reticulum of the muscle fiber is considered as sarcoplasmic reticulum.

Hence, The correct answer is option (B).

Note: Sarcomere in the striated muscles are responsible for muscle contractions, the proteins involved are actin which binds with myosin while flexing, whereas myosin is the protein that is globular in structure.