Question

Which of the following statements are correct regarding skeletal muscle?

1. Muscle bundles are held together by collagenous connective tissue layer called fascicle.
2. Sarcoplasmic reticulum of muscle fibre is a store house of calcium ions.
3. Striated appearance of skeletal muscle fibre is due to distribution pattern of actin and myosin proteins.
4. M line is considered as functional unit of contraction called sarcomere.

Choose the most appropriate answer from the options given below:

• A. B and C only
• B. A, C and D only
• C. C and D only
• D. A, B and C only

Answer 1

The Correct Option is A

To determine the correct statements regarding skeletal muscle, let's evaluate each provided statement:

1. Muscle bundles are held together by collagenous connective tissue layer called fascicle. This statement is incorrect. Muscle bundles, also known as fascicles, are indeed surrounded by a connective tissue layer, but it is called the perimysium, not fascicle. The term "fascicle" refers to the bundle itself, not the connective tissue.
2. Sarcoplasmic reticulum of muscle fibre is a store house of calcium ions. This statement is correct. The sarcoplasmic reticulum in muscle fibers serves as a storage site for calcium ions, which are critical for muscle contraction.
3. Striated appearance of skeletal muscle fibre is due to distribution pattern of actin and myosin proteins. This is a correct statement. The striated appearance is due to the arrangement of actin (thin filaments) and myosin (thick filaments) within the muscle fiber, which creates a repeating pattern of dark (A bands) and light (I bands) stripes.
4. M line is considered as functional unit of contraction called sarcomere. This statement is incorrect. The functional unit of contraction in a muscle fiber is called a sarcomere, but it spans from one Z line to another. The M line is found in the middle of the sarcomere and serves as an attachment point for the thick filaments.

Based on the evaluation above, the correct statements are B (Sarcoplasmic reticulum as a calcium ion store) and C (Striated appearance due to actin and myosin distribution). Therefore, the correct answer is:

B and C only