Question

The diagram given below represents the histology of a stripped muscle. Which one of the following has the correctly matched label of the parts A, B, C, D, E and F?
A) A. Sarcoplasm, B- Nucleus, C-Sarcolemma, D-myofibril, E-Dark band, F-light band
B) A. Sarcoplasm, B- light band, C- myofibril, D- Sarcolemma, E- Nucleus. F-Dark band
C) A- Light band, B- Sarcoplasm, C- myofibril, D- Sarcolemma, E- Nucleus. F-Dark band
D) A- Sarcolemma, B- Nucleus, C-Dark band, D- Light band, E- Sarcoplasm, F- Myofibril

Answer 1

Hint: The diagram given is a section of skeletal muscle. The muscle is made up of several repeating units called sarcomeres which are the functional units of the muscles. Due to the presence of sarcomeres, the brands are visible in the muscle fibres. These bands give a striated appearance to the muscles.

Complete answer:
To answer this question, we must know about the structure of the muscle cell. The muscle cell comprises long fibres and cells which are cylindrical in shape. It consists of several nuclei. The “E” labelled in the above diagram is the nucleus. The sarcolemma is the cell membrane which encloses the muscle fibres. It is labelled as “D”. It is lipo-protein in nature and adheres with the basement membrane.

The skeletal muscles have a distinct pattern of bands called the dark band and the light band. This is the reason why the muscles look striated. This appearance is due to the myofibrils represented as “C”. Myofibrils are the long filaments which run parallel to each other to form muscle fibres.
“A” represents the light band also known as I-band. It contains less myofibrils.
“F” represents the dark band and is known as the Z-band. This region contains numerous myofibrils.
“B” represents the sarcoplasm is the cytoplasm of the striated muscles. It plays a major role in muscle contraction.

Thus the correct answer is option ‘C’.

Note: The myofibrils are made up of repeated units called the sarcomeres. It is made up of four proteins actin, myosin, troponin, tropomyosin which functions in carrying out contraction in the muscles.