MUSCLES  Like a machine, your body consists of many parts that move. Those parts are your bones and muscles.

Muscle Action  There are two types of muscle actions  Voluntary – You control the movement  Involuntary – You can’t control the movement  When you pick up an object it is a voluntary movement.  However, the beating of your heart and movement of your digestive track are involuntary.

Muscle System Function  The major function of the muscular system is to move bones. It also provides support and protection for your organs.  Muscles and bones work together with your nervous system to move your body. (what three systems are these again?)

Parts of the Muscle System  3 Types of Muscle  Smooth, Skeletal, Cardiac  Tendons – Attach muscle to bone

Skeletal muscles  Skeletal muscles are made of skeletal muscle tissue. Most of your body is skeletal muscle.  Skeletal muscle is made up of fibers bound together by connective tissue which also contain blood vessels and nerves.  Muscle fibers contain long muscle cells with thousands of mitochondria for energy.

Flexors and Extensors  Muscles work in pairs called flexors and extensors  To bend a part of your body, a flexor is used.  To straighten part of your body, an extensor is used.  They provide ALL movement of your skeleton.

Skeletal Muscles  All muscle works in pairs and to cause movement muscles must contract or extend.  When a muscle contracts, it causes muscle fibers to shorten (contract).  When a muscle relaxes, it causes muscle fibers to extend and return to their original length.

Healthy Muscles  Skeletal muscles tire quickly. To keep them healthy (as well as your entire body healthy) you should do resistance exercises (weights). This increases muscle strength.  Aerobic exercise also increases the endurance of skeletal muscle