1. Muscular System Victoria Emi Jorge Jonathan

2. Muscular System Facts . There are over 600 muscles that make up the muscular system . Muscles are bundles of fiber held together by connective tissue . There are 3 main kinds of muscle, Cardiac, Visceral, and Skeletal

3.  Cardiac muscle: forms the walls of the heart and contracts to circulate blood  Visceral muscle contracts to cause movement in these organs.  Visceral (smooth) muscle is found in the internal organs of the body such as those of the digestive and respiratory systems, and the blood vessels and eyes.  Cardiac and Visceral muscle are involuntary, meaning they function without conscious thought or control.  Skeletal muscle is attached to bones and causes body movement  Skeletal muscle is voluntary because a person controls its action.

4. Properties & Characteristics  Excitability-irritability, the ability to respond a stimulus such as nerve impulse  Extensibility- the ability to be stretched  Elasticity- allows the muscle to return to its original shape after it has contracted or stretched  Contractibility- muscle fibers that are stimulated by nerves contact, or become short and thick, which causes  movement

5. Action and Movement  Adduction- moving a body part toward the midline  Abduction- moving a body part away from the midline  Flexion- decreasing the angle between two bones, or bending a body part  Rotation- turning a body part around its own axis; for example, turning the head from side to side  Extension-Increasing the angle between two bones, or straightening a body part 

6.  Skeletal muscles attach to bones in different ways such as tendons and by fascia.  Tendons: are strong tough connective tissue cords  Fascia: is a tough sheet like membrane that covers and protects the tissue.  An Origin is when a muscle attaches to a bone and the end does not move.  The end that does move when the muscle contracts is called the Insertion.  Muscles are partially contracted at all times, even when we don’t use them.  They are always in a state of muscle tone (state of readiness to act)

7.  It’s important to continuously use our muscles because lack of muscle tone can give as paralysis.  Our muscles can shrink in size and lose strength with lack of muscle use, you can also develop contracture, a painful severe tightening of a flexor muscle resulting in bending of a joint.

8. Thank you for your time!