Skeletal Muscle Physiology

There are three types of muscle skeletal which are voluntary, smooth muscle which are involuntary and cardiac muscle. Muscle is made up of protein filaments, myosin and actin. These filaments slide past each other to produce a contraction which changes both the length and shape of the cell. The primary function of the muscle is to produce both movement and force.
Skeletal muscle is composed of bundles of muscle fibres containing myofibrils of thick and thin filaments (myosin and actin). Skeletal muscle have distinct striations due to the overlapping of the myosin and actin held in place by the sarcolemma. Skeletal muscles cover majority of the skeleton, giving shape and the ability of movement. They are attached to the skeleton by strong tendons
The muscles in the abdominal regions are constantly contracting to hold the head in place and maintain posture. Within the digestive and urinary systems an important skeletal muscle is present. The sphincter muscle are located at the ends of the digestive and urinary systems and function in controlling the opening and closing of these systems (study.com). Skeletal muscle also has homeostasis functions. Homeostasis is the maintenance of internal environment (study.com). Due to the contraction of skeletal muscles energy is given off and heat produced which each contraction. The heat produced helps to maintain the body's internal temperature and therefore is an effective
Smooth muscles do not fatigue and are constantly working in the digestive system to move food and substances through the body through peristalsis (contraction and relaxing). They also work continuously within the bladder. The relaxing of the smooth muscles allows an individual to hold their urine until they reach a bathroom and the contraction of these muscles allow the urine to be pushed out. Similarly in a women's uterus smooth muscles help push the baby out when in labor.
For a smooth muscle to contract cross bridges firstly must be established. The thin filaments will slide past the thick filaments. This causes shortening of the muscle in all directions. Similarly calcium ions are required in smooth muscles to relax again. They bind to myosin breaking up ATP into ADP and transfer Pi activating the myosin to form cross bridges with actin. When the calcium is removed from the cell the myosin is not stimulated and therefore relaxes