MEDICAL PHYSIOLOGY

Detailed explanation-1: -The striated appearance of skeletal muscle tissue is a result of repeating bands of the proteins actin and myosin that are present along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes the entire cell to appear striated or banded.

Detailed explanation-2: -These dark and light bands are called A-bands and I-bands respectively. The A-band is made up of myosin filaments whereas the I-band is made up of actin filaments alone. A-Bands are the anisotropic bands of the sarcomere. I-Bands are the isotropic bands of sarcomere.

Detailed explanation-3: -I-band is the zone of thin filaments that is not superimposed by thick filaments (myosin). Following the I-band is the A-band (for anisotropic). Named for their properties under a polarized light microscope. An A-band contains the entire length of a single thick filament.

Detailed explanation-4: -The contractile units of the myofibril, the sarcomeres, are distinguished by the striated distribution of their proteins, visible by light microscopy as three major bands, called A, I, and Z (Fig. 1). A bands comprise thick filaments of myosin and proteins that bind myosin.

Detailed explanation-5: -The arrangement of the thick myosin filaments across the myofibrils and the cell causes them to refract light and produce a dark band known as the A Band. In between the A bands is a light area where there are no thick myofilaments, only thin actin filaments. These are called the I Bands.