Muscular System: Review
Muscular System: Movement
The muscular system consists of greater than 600 individual muscles and accounts for just under half of the total body weight of an adult. Muscle tissue is specialized with the ability to contract and relax when stimulated which allows a person to move. Functions of the muscular system include production of movement, maintenance of posture, and generating heat.
- Muscle movements can be classified as voluntary (conscious) and involuntary (unconscious). There are three types of muscles in the body that are unique in structure and function: skeletal, smooth, and cardiac.
- Muscle contractions are initiated by the nervous system. The contraction is made possible by the structure of muscle fibers. Muscle fibers are made of hundreds of organelles called myofibrils which in turn are made of a bundle of contractile proteins called muscle filaments. There are two main types: thin actin filaments and thick myosin filaments. These filaments are arranged in functional units called sarcomeres. The sliding filament theory describes how these filaments work together in a sarcomere to create a muscle contraction.
- Skeletal muscle is made up of hundreds, or even thousands, of these muscle fibers along with connective, nerve, and vascular tissues. In order to function properly, muscles depend upon the skeletal system. Tendons connect muscles to bones. Muscles often work in antagonistic pairs to create a movement. Skeletal muscle can vary in size, shape, and arrangement of fibers. There are seven general types of muscles: circular, convergent, unipennate, parallel, bipennate, parallel fusiform, and mulitpennate. Be sure to review the major muscles of the body.
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