MEDICAL PHYSIOLOGY

Detailed explanation-1: -The myofibrils are made up of thick and thin myofilaments, which give the muscle its striped appearance. The thick filaments are composed strands of the protein myosin, and the thin filaments are strands of the protein actin, along with two other muscle regulatory proteins, tropomyosin and troponin.

Detailed explanation-2: -Myofibrils are composed of long myofilaments of actin, myosin, and other associated proteins. These proteins are organized into regions termed sarcomeres, the functional contractile region of the myocyte.

Detailed explanation-3: -Muscles are composed of two major protein filaments: a thick filament composed of the protein myosin and a thin filament composed of the protein actin. Muscle contraction occurs when these filaments slide over one another in a series of repetitive events.

Detailed explanation-4: -The actin to myosin filament ratio varies from 3 to 4 within each individual myofibril. The described variability of the actin filaments arrays leads to several difficulties in an explanation of the mechanism of muscular contraction.