The muscles of the body are divided into three basic type of muscular tissue - skeletal, cardiac, and smooth. The skeletal muscle tissue is packaged into skeletal muscles, organs that attach to and cover the bony skeleton. The skeletal muscle is also known as the voluntary muscle. The voluntary are called because a person controls there use. Skeletal muscle fibers are the longest muscle cells and have obvious stripes called striations. It’s responsible for overall body mobility. It also can contract rapidly but it tires easily.
The cardiac muscle tissue occurs only in the heart, where it constitutes the bulk of the heart walls. Cardiac muscle tissue is involuntary. The cardiac muscle tissue usually contracts at a fairly steady rate set by the heart’s pacemaker. It also is used as the body’s blood pump. Neural controls allow the heart to speed up to up for brief periods. Smooth muscle tissue is found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages. Unlike cardiac and skeletal muscle smooth muscle has no striations. Its role is to force fluids and other substances through the internal body channels. The smooth muscle tissue is also involuntary. Involuntary is when a person generally can’t control them.
Muscle fatigue is a state of physiological inability to contract even though the muscle still may be receiving stimuli. Lack of ATP is not a fatigue-producing factor in moderate exercise. Several ionic imbalances contribute to muscle fatigue as action potentials are transmitted, potassium is lost from the muscle cells, and accumulates in the fluids of the T tubules. Lactic acid has long been assumed to be a major caused of fatigue, and excessive intracellular accumulation of lactic acid (which causes the muscle to ache, raises the concentration of H+ and alter contractile proteins. Lactic acid actually counteracts high K+ levels, which do lead to muscle fatigue.
Whether or not fatigue occurs, vigorous...