What are involuntary muscles?

involuntary muscles are muscles that are not consciously controllable, and instead are withdrawn due to unconscious impulses sent by autonomic nervous system or some specialized cells or hormones. Hunger muscle and heart muscles can be classified as involuntary muscles. The smooth muscle consists of spindle -shaped cells that have no stripes and are found in many places throughout the human body. The heart muscle is more striped than smooth and is only found in the walls of the heart. Thin fibers are composed of globular protein called actin, while thick are formed by a motor protein called myosin. Smooth muscles require that extracellular calcium ions required to reduce contracts: ions activate nucleotide called adenosine triphosphate (ATP), which then activates myosin filaments. Tmyosin fibers connect to actin fibers in a process known as CrossBridge Cycle, which causes strong and thin fibers to slide and pull over each other. When myosin fibers releaseactin fibers, muscles relax.

There are many types of smooth muscles in the human body. Smooth involuntary muscles control the iris of the eye, which are withdrawn and involuntarily expanding in accordance with the changing light level. The process of peristalsis that creates a wool that promotes food through the esophagus and small intestine is also controlled by involuntary muscles. The smooth muscle can also be found in the respiratory tract, in the reproductive systems of women and men, the ciliary muscle of the eye and the bladder. Most blood and lymphatic vessels in the human body are lined with smooth muscle cells, allowing them to reduce and dilateate.

Heart and is also sometimes considered involuntary muscles. However, the heart muscle shares features of smooth and skeletal tissues. It is striped like skeletal muscle tissue, but its contractions are involuntary, as the contraction of tissue of smooth muscles. The heart muscle is unique in that it is particularly invulnerable for fatigue.

heart muscle contractions are controlled by nerve impulses supplied by a group of cells located in the right atrium of the heart called sinoatrial knot. These contractions push blood by four chambers of the human heart, halls and chambers. They also move blood during the veins and arteries of the circulatory system. These contractions, as well as smooth muscle contractions, are initiated by calcium ions that come from the outer muscle cell.