Contractile Proteins are Found in Which Part

Contractile Proteins Are Found In 

(A) Bones 

(B) Blood 

(C) Muscles 

(D) Cartilage?

Answer: (c) Muscles

Contractile proteins are found in muscles. 

The contractile proteins are the most important components of muscles. These proteins are made of amino acids and are primarily composed of actin and myosin. The contractile proteins are found in the sarcomere, which is a small unit composed of filaments that can be seen under a microscope. 

The process by which muscle cells contract is called excitation-contraction coupling (ECC). This process takes place when a signal from the neuron reaches the muscle cell and triggers an action potential. The action potential then travels to the sarcomere. Where it causes calcium ions to enter the cell through voltage-gated ion channels, this influx of calcium ions causes them to bind with troponin and tropomyosin, which changes their shape, so they inhibit contraction. 

When this happens, the myosin begins to interact with actin, and the interaction of myosin and actin causes the sarcomere to shorten. A muscle consists of several cells organized into units called fascicles that contract when stimulated to move an animal or object.

The contractile unit is called a muscle fibre, which contains many sarcomeres that shorten in response to electrical impulses from the central nervous system. The contraction of muscle fibres produces movements (usually contractions) of bones, blood vessels, and other tissues. One type of muscle fibre is smooth muscle, which consists of long cells that undulate and contract when stimulated by electrical impulses. 

Smooth muscle is found in the walls of hollow organs such as the stomach, intestine and blood vessels. The cells of skeletal muscle, which contract to move, are arranged into units called sarcomeres (singular: sarcomere) that serve as internal units for contraction. Skeletal muscle fibres contain myofibrils that are composed of several sarcomeres. The sarcomere has two types of actin and myosin filaments that are arranged perpendicular to each other. Myosin filaments are the long thin protein structures made of actin and myosin that extend from the Z-line region to the M-line region.