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Muscular System

I. Three Types of Muscle ( "The meat on our bones")

    A. Skeletal Muscle

        1. Striped (striated) appearance

        2. Many functions = Many nuclei

        3. Attached to our bones (relax & contract)

            a. Lets us bend & twist our joints

        4. Muscles control our every move

        5. In men:

            a. approx. 40% of body weight

        6. In women:

            a. lower muscle mass, more fat

        7. Largest Muscle: Gluteus Maximus, Smallest Muscle: Middle Ear

    B. Smooth Muscle

        1. control movements of internal systems

            a. digestive, circulatory, urinary, reproductive

    C. Cardiac Muscle

        1. only found in the heart

    D. All muscle

        1. made of mostly proteins

II. Your Skeletal Muscle

    A. Long & Smooth

        1. Attached to bones (some facial muscle is attached to skin)

        2. Relax & contract

    B. Flat Muscle

        1. Diaphragm- breathing

        2. Sphincter Muscle-circular

            a. anus, digestive system

    C. Abdomen

        1. Can't be protected by bone (3 muscles instead)

            a. stomach expansion, pregnancy

    D. Tendons

        2. Connect Muscles to Bones

III. Contracting Muscles

    A. Chemicals

        1. Myosin & Actin (proteins)

            a. Make the myofibrils of a muscle cell slide over each other to shorten the cell

            b. Can shorten by up to 1/3 the original size ( muscles work in pairs, Flexors & Extenders)

                (1.) Stronger contractions more cells

    B. Glucose from carbohydrates + Oxygen = Energy

    C. Exercise- increases cell size (makes more blood vessels)

        1. Lactic Acid- forms when oxygen isn't in the proper quantity

        2. Muscles need oxygen!

        3. Aerobic exercise

            a. 20-30 min. per day w/ strength training

            b. Builds muscle

    D. Red muscle, White muscle

        1. Red

            a. Lasts long

        2. White

            b. More force (shorter activity)

    E. Muscle Tone

        1. Flexors & extenders are slightly contracted at all times

        2. Muscle wastage

            a. Atrophy- loss of muscle mass, replacement by fat

IV. How you scratch your nose

    A. Nervous System Controls muscles

        1. Muscles Contract

        2. If our nervous was less efficient, we could punch ourselves in the face