Muscle contraction

Muscle contraction is the process by which muscle fibres generate tension and force, resulting in movement or stabilisation of the body. Muscle contraction is essential for a wide range of physiological processes, including movement, respiration, and digestion.

Muscle contraction occurs as a result of the interaction between two types of proteins within muscle fibres: actin and myosin. When stimulated by a nerve impulse, the muscle fibre releases calcium ions, which bind to the protein complex known as troponin, causing a shift in the position of the protein tropomyosin. This shift exposes the active sites on the actin filaments, allowing myosin to bind and generate force.

The force generated by muscle contraction can be influenced by a wide range of factors, including the frequency and intensity of nerve impulses, the length and composition of muscle fibres, and the presence of certain hormones and other signalling molecules.

There are three main types of muscle contraction: concentric, eccentric, and isometric. Concentric contraction occurs when the muscle shortens as it generates force, such as when lifting a weight. Eccentric contraction occurs when the muscle lengthens as it generates force, such as when lowering a weight. Isometric contraction occurs when the muscle generates force without changing length, such as when holding a weight in a fixed position.



Muscle contraction