The Muscular System Unit 8b

Types of Muscle I. Smooth Muscle (visceral) A. Found in internal organs 1. The walls of blood vessels 2. The lining of the stomach and intestines B. Involuntary muscle (cannot be consciously controlled)

II. Cardiac Muscle A. Muscle that makes up the heart B. It is involuntary C. Forms a branching, woven network of muscles

III. Skeletal Muscle A. This muscle is attached to bone to move part of the skeleton B. They are voluntary muscle (consciously controlled) http://www.youtube.com/watch?v=f_tZne9ON7c

Movement in Skeletal Muscle I. Skeletal muscle attaches to bone by thick bands of connective tissue called tendons A. Tendons are not elastic

B. Muscles have two points of attachment 1. Origin-stationary connection gives the muscle something to pull against 2. Insertion-attached to the bone that will move when it contracts (shortens) 3. A muscle’s insertion always moves toward the origin

C. Skeletal muscles always occur in pairs and exert opposable forces-all controlled by nervous system 1. Flexors-cause limb to bend at the joint Decrease / shorten angle 2. Extensors-cause limb to straighten Increase / lengthen angle

3. Abductors-move limbs away from the body 4. Adductors move limbs toward the body Fun Facts: 1. Where is the largest muscle in the body? ANS: Gluteus Maximus 2. Where is the smallest muscle in the body? ANS: in your ear

Muscle Fiber I. Muscle composed of thousands of fibers. A. Muscle cells lined up end to end

B. Smaller fibers within called myofibrils 1. Thick filaments of protein inside called myosin (ATP) 2. Thin filaments of protein inside called actin (troponin & tropomyosin) 3. Actin and myosin form sarcomere-the functional unit contraction in myofibril

1. Bundles of muscle fiber (fasicle) II. Muscle movement requires ATP 1. Bundles of muscle fiber (fasicle) 2. Muscle Fiber 3. Myofibrils 4. Sarcomere made of protein filaments 5. Filaments are actin and myosin

III. Sliding Filament Theory A. Contraction occurs when myosin “walks” along actin. B. Movement pulls Z lines together (actin is attached to Z line)

Fun Fact: if all muscles worked together you could lift 10 tons C. Sarcomeres shorten and causes contraction. D. Contraction is all or none E. Strength of movement depends on how many motor units are called to action Fun Fact: if all muscles worked together you could lift 10 tons

White board explanation http://www. youtube. com/watch White board explanation http://www.youtube.com/watch?v=MZJ6kTKDFmw College Professor Explanation http://www.youtube.com/watch?v=lXOHPokR6NQ