Muscular system The function of the muscular system

Muscular system

The function of the muscular system is to create movement, protect organs, aid digestion, and ensure blood flow

Smooth muscle provides structure for the walls of hollow organs like the bladder, stomach, and blood vessels with uninucleated muscle cells that contract involuntarily. • Smooth muscle has the ability to stretch and maintain tension for long periods of time, such as uterine contractions during childbirth Skeletal muscles attach to the skeleton and come in pairs. They are responsible for motion, and usually contract voluntarily. A short single contraction is a twitch, and a sustained contraction is tetanus. Skeletal muscle cells are multinucleated Cardiac muscle is found only in the heart, and it is characterized by endurance and consistency. It can stretch in a limited way, like smooth muscle, and contract with the force of a skeletal muscle. It is a twitch muscle only and contracts involuntarily.

molecules of acetylcholine diffuse across the neuromuscular cleft and trigger a muscle contraction.

1. the impulse is transferred from a neuron to the sarcolemma of a muscle cell. 2 - The impulse travels along the sarcolemma and passes to the sarcoplasmic reticulum. 3 - Ca 2+ diffuses out of the SR and among the myofilaments. 4 -Calcium fills the binding sites in the troponin molecules. the shape and position of the tropinin changes which in turn causes movement of the attached tropomysin molecule. 5 - Movement of tropomysin allows the myosin head to contact actin. 6 - Contact with actin causes the myosin head to swivel.

• • • The most common type of inherited muscular disorder is muscular dystrophy. This disease causes muscles to progressively waste away. There are six forms of muscular dystrophy. The most frequent form appears in boys aged three to seven, because it’s a sex-linked condition. Approx. 1 in 544, 00 live births will have MD. The first manifestation of the disease is clumsiness when walking. This occurs because the muscles of the pelvis and the thighs are first affected. The disease spreads to muscles in other areas of the body, and by the age of ten, a child is usually confined to a wheelchair or a bed. Death usually occurs before adulthood. Treatment usually focuses on delaying or alleviating symptoms, with corticosteroids and physical therapy.

• Fibromyalgia causes widespread chronic musculoskeletal pain, accompanied by fatigue. Researchers believe that fibromyalgia amplifies painful sensations by affecting the way the brain processes pain signals. • The disorder affects an estimated 10 million people in the U. S. and an estimated 3 -6% of the world population. Symptoms sometimes begin after a physical trauma, surgery, infection or significant psychological stress. In other cases, symptoms gradually accumulate over time with no single triggering event. • Women are much more likely to develop fibromyalgia than are men. • While there is no cure for fibromyalgia, a variety of medications can help control symptoms. Exercise, relaxation and stress-reduction measures also may help.

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