Muscle Physiology essays

Muscle Physiology essays Muscles differ in shape, size, and purpose. There are three categories of muscles in the human body. These categories are skeletal, smooth and cardiac muscle. The skeletal is attached to bone and moves the skeleton under voluntary control. The smooth forms the walls of blood vessels and body organs to modify the activity of body parts under involuntary control. The cardiac is the muscle of the heart which provides contractile activity under involuntary control. Skeletal Muscle movements are controlled by nerve impulses sent to motor units causing muscle contractions. Skeletal muscles are made up of bundles of fibres, containing many nuclei, connected to the bone by connective tissue attachments called tendons. Its function is to position parts of the skeleton to allow movement. Each fibre is made up of a number of myofilaments. Myofibrils are thread like fibres which run along one another within the muscle fibre. Furthermore, within myofibrils are contained contractile sheaths called sarcomeres. In turn these consist of thick (myosin) and thin (actin) protein myofilaments. While contractions occur the myosin and actin filaments slide across one another causing the sarcomeres to shorten. When many sarcomeres shorten at once, the entire fibre contracts thus creating movement. Muscles are surrounded by connective tissues. These consist of two types of protein fibres, collagenous and elastic. Collagnous tissue provides resistance to tension while elastic tissue provides elasticity. These connective tissues consist of tendons, ligaments and fascial sheaths. The fascial sheaths are categorized into three types. The three categories are Endomysium, Perimysium, and Epimysium. Endomysium are the inner sheaths and bind single muscle fibres, perimysium are sheaths which binds numerous muscle fibres, and epimysium are the outer sheaths which bind the entire muscle fibre. ...