ANATOMY

Detailed explanation-1: -The I-band is the region on either side of a Z-disc that contains only thin filaments and titin. This partial overlap in filaments makes the A-band darker at its ends, leaving a light area in the middle (H-band) where there is no overlap with the light bands.

Detailed explanation-2: -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.

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 sarcomeric Z-disk, the anchoring plane of thin (actin) filaments, links titin (also called connectin) and actin filaments from opposing sarcomere halves in a lattice connected by alpha-actinin.

Detailed explanation-5: -The I band is a region on the sarcomere that only contains actin filaments, which makes it appear lighter in color and is the reason why it’s sometimes called the light band comparatively to the other regions of the sarcomere which will all contain some myosin filaments and will therefore appear darker.