Locomotion and Movement Test - 2

Actin filament help in contraction and relaxation of muscles. Actin filament are found in all eukaryotic cells but it is absent in nematode sperms.

Myology is the study of the muscular system, including the study of the structure, function and diseases of muscle.

Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fascia. Each muscle bundle contains a number of muscle fibres. A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils. The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere.

Actin and myosin filaments are responsible for contraction and relaxation of muscle. The discovery of actin is credited to Straub.

Muscles are attached to bones by tendon and bones are attached with another bone by ligaments. Tendon and ligaments are types of connective tissue.

A functional G-actin molecule in its free state is bound to magnesium ion and ATP. G-actin molecule forms a bridge between the muscle fibres for sliding.

Each meromyosin has two important parts, a globular head with a short arm and a tail.

Muscle fibres have properties of excitability, elasticity and contractility but conductivity is not present in muscles fibers. These fibres help in movement of different body parts.

Myoglobin is found to be highly abundant in muscles of whales and seals. Myoglobin being oxygen and iron binding protein allowing organisms to hold their breathe longer underwater.