The Muscular System

CAN YOU SIT STILL AND NOT MOVE A MUSCLE?

CAN YOU SIT STILL AND NOT MOVE A MUSCLE? Are you breathing? Is your chest expanding? Are you producing saliva(spit) in your mouth? Did you swallow?

IT IS IMPOSSIBLE TO SIT STILL AND NOT MOVE A MUSCLE!! Approximately 40% of your body weight is made up of muscles.

HOW MANY MUSCLES DOES A BODY HAVE? Almost 700 countable skeletal muscles Several million hair-raising muscles Several billion smooth muscles cells blended together Exactly 1 heart muscle

Types of Muscles 2 groups of muscles in the body Involuntary – you have no control over Ex’s: Breathing and Digesting Food Voluntary – you have control over Ex’s: Smiling, Getting out of your chair

3 TYPES OF MUSCLES

TYPES OF MUSCLES Skeletal Location – attached to the bones of your skeleton Voluntary Striated (banded)

SKELETAL MUSCLES Move and support the skeleton Skeletal muscles react quickly and tire easily There are over 600 skeletal muscles

TENDON A strong connective tissue that attaches skeletal muscles to bones

TYPES OF MUSCLES Smooth Location – Inside many internal organs Involuntary Not striated

SMOOTH MUSLCES Found on the inside of the stomach, blood vessels, and intestines. React slowly and tire slowly.

TYPES OF MUSCLES Cardiac Location – Heart only Involuntary Striated

CARDIAC MUSLCES Involuntary Muscle Muscle cells are striated Does NOT get tired It contracts repeatedly this is called a heartbeat

MUSCLES AT WORK Muscles work by CONTRACTING. What does a contracting muscle look like? Muscles become shorter and thicker. When do muscles contract? When they receive messages from the nervous system

MUSCLES PULL NOT PUSH! Skeletal muscles can only contract and must work in pairs While one muscle contracts, the other muscle relaxes and returns to its original length.

HOW DO MUSCLES WORK? To bend the elbow The bicep muscle contracts (gets shorter) The triceps muscle contracts to return bicep to its original length