The muscular system is an organ system consisting on skeletal, smooth and cardiac muscles. It permits movement of the body, maintains posture, and circulates blood throughout thebody. The muscular system in vertebrates is controlled through the nervous system, although some muscles (such as the cardiac muscle) can be completely autonomous.There are threedistinct types of muscles: skeletal muscles, cardiac or heart muscles, and smooth (non-striated) muscles. Muscles provide strength, balance, posture, movement and heat for the body to keep warm.
Uponstimulation by an action potential, skeletal muscles perform a coordinated contraction by shortening each sarcomere. The best proposed model for understanding contraction is the sliding filament model ofmuscle contraction. Actin and myosin fibers overlap in a contractile motion towards each other. Myosin filaments have club-shaped heads that project toward the actin filaments.
The muscular systemmakes up nearly half the weight of the human body, this is why when we train we sometimes put on weight instead of losing it. We put on muscle weight.
The muscles provide the forces that enable thebody to move. Muscles stretch across joints to link one bone with another and work in groups to respond to nerve impulses. There are three types of muscle:
• There are nearly 650skeletal muscles in the human body!
• Skeletal muscles are attached to the skeleton
• They work in pairs: one muscle moves the bone in one direction and the other moves it back again
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