muscular+system+rich

Muscular System Chapter 12 pp 227-236 (New Unit called Move it) 1. What are the three types of muscles in the body and what is the function of each? Smooth muscles: theses are little single nucleus cell fibers on the inside of hollow organs which enable them to contract. Cardiac muscles:they line the heart wall and are uninucleated and they are branched so they can interlock. The contractions are involuntary and rhythmic. Skeletal muscles: made of fibers that attach to the skeleton. skeletal muscles have numerous functions that are voluntary. 2. How do skeletal muscles work together to cause the bones to move? The muscles generally work in groups to move bones, but there is a primary mover in all contractions. Because muscles can only pull, they work in opposite pairs. The muscle that works opposite of the prime muscle is the antagonist. 3. Insert an image of the major muscles in the body like the one on page 231. You will need to know the location and function of the following (write the function next to the name -- see page 231) Pectoralis major: moves arms out and across the body. Deltoid: enables lifting of arm from side and up and down movement of the arms. trapezius: lifts/pulls head backward towards back. holds up head. biceps brachii: pulls forearm to shoulder, bends arm at elbow. triceps brachii: unbends/straightens arm at elbow. External oblique: contracts abdomen and enables turning of abdomen and forward lift of head and chest. latissimus dorsi: brings arm back behind torso. gluteus maximus: enables standing, walking, squating. bends thighs backward. quardriceps femoris:straightens leg at knee. gastrocnemius: pulls foot downward and bends leg at knee.

4. Define myofibrils, sarcomeres, myosin, actin myofibrilis are the long components that make up the muscle fibers. Sarcomeres are the main structure of the E shaped brackets that contract the myofibrils. The myosin are the little row boats that pull the sarcomeres together and apart and contract the muscle. The actin are the things that make up the sarcomeres.

5. Describe the structure of a sarcomere's thick and thin filaments. The sarcomere is made up of thick and thin filaments comprise the lining of the sarcomere. The actin are thin and the myosin are thick. 6. Describe the sliding filament model and insert image (How does the sarcomere contract?) The muscle contracts when the sarcomeres shorten due to the contraction of the myofibrilis and the actin slide down to the center.