The main characteristic of muscle tissue is its ability to contract. When stimulated, muscles shorten to produce movement of the skeleton, vessels, or internal organs. Muscles also may remain partially contracted to maintain posture. In addition, the heat generated by muscle contraction is the main source of body heat.
Types of Muscle :There are three types of muscle tissue in the body:
(visceral) muscle: This makes up the walls of the hollow organs and the walls of ducts, such as the blood vessels and bronchioles. This muscle operates involuntarily and is responsible for peristalsis, the wavelike movements that propel materials through the systems.
2)CARDIAC MUSCLE:
This makes up the myocardium of the heart wall. It functions involuntarily and is responsible for the pumping of the heart.
3)SKELETAL MUSCLE:
This is attached to the bones of the skeleton and is responsible for voluntary movement. It also maintains posture and generates a large proportion of body heat. All of these voluntary muscles together make up the muscular system. The discussion that follows describes the characteristics of skeletal muscle, which has been the most extensively studied of the three types of muscle tissue.
Skeletal muscles are stimulated to contract by motor neurons of the nervous system. At the neuromuscular junction (NMJ), the point where a branch of a neuron meets a muscle cell, the neurotransmitter acetylcholine is released, prompting contraction of the cell. Two special proteins in the cell, actin and myosin, interact to produce the contraction. ATP (the cell’s energy compound) and calcium are needed for this response. Most skeletal muscles contract rapidly to produce movement and then relax rapidly unless stimulation continues. Sometimes muscles are kept in a steady partially contracted state, to maintain posture, for example. This state of firmness is called tonus, or muscle tone.
► MUSCLE ACTION:
Muscles work in pairs to produce movement at the joints. As one muscle, the prime mover, contracts, an opposing muscle, the antagonist, must relax. For example, when the biceps brachii on the anterior surface of the upper arm contracts to flex the arm, the triceps brachii on the posterior surface must relax. When the arm is extended, these actions are reversed. In a given movement, the point where the muscle is attached to a stable part of the skeleton is the origin, the point where a muscle is attached to a moving part of the skeleton is the insertion. Muscle Structure Muscles are composed of individual cells, often referred to as fibers because they are so long and threadlike. These cells are held together in bundles by connective tissue. Covering each muscle is a sheath of connective tissue or fascia. These supporting tissues merge to form the tendon that attaches the muscle to a bone. Regular exercise or physical activity at least 30 minutes a day ,will makes your muscular system strong. for any corrections or recommendation, fill the below box,or send sms at 09035907765.
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