ANATOMY

Detailed explanation-1: -The thin bands are made of multiple molecules of a protein called actin. The thin actin bands are attached to a Z-line or Z-disk of an elastic protein called titin. The titin protein also extends into the myofibril anchoring the other bands in position. From each Z-line to the next is a unit called the sarcomere.

Detailed explanation-2: -The Z-band in vertebrate striated muscle crosslinks actin filaments of opposite polarity from adjoining sarcomeres and transmits tension along myofibrils during muscular contraction.

Detailed explanation-3: -Medical Definition Z line. noun. : any of the dark bands across a striated muscle fiber that mark the junction of actin filaments in adjacent sarcomeres.

Detailed explanation-4: -The sarcomere is the fundamental unit of contraction and is defined as the region between two Z-lines.

Detailed explanation-5: -Expert Answer. The answer is “actin protein”. A muscle fiber’s contractile unit is called a sarcomere which is present between two Z-lines. This means the Z-lines form a sarcomere’s borders.