MEDICAL PHYSIOLOGY

Detailed explanation-1: -Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes.

Detailed explanation-2: -Sarcomeres are the basic contractile units of cardiac muscle. They are composed of thick and thin filaments essential for generation and propagation of mechanical force.

Detailed explanation-3: -The myofibrils are made up of thick and thin myofilaments, which help give the muscle its striped appearance. The thick filaments are composed of myosin, and the thin filaments are predominantly actin, along with two other muscle proteins, tropomyosin and troponin.

Detailed explanation-4: -Skeletal and cardiac muscles are known as striated muscles, because the filaments of actin and myosin that power their contraction are organized into repeating arrays, called sarcomeres, that have a striated microscopic appearance.

Detailed explanation-5: -There are between 2, 000 and 2, 500 sarcomeres found together in linked coils in each 10 millimetres of muscle fibre. To watch the sarcomeres in action, the researchers first had to isolate a single myofibril (the basic rod-like units which make up muscle tissue) and then zoom in on an individual sarcomere.