Muscular+system+GS

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 muscle- Sustains prolonged contractions and does not fatigue easily. Cardiac muscle- forms the heart wall. Skeletal muscle- The muscle is voluntary because it allows us to move what we want to in the body. 2. How do skeletal muscles work together to cause the bones to move? Skeletal muscles support the body, make bones move, help maintain a constant body temperature, and help stabilize joints and protect internal organs. 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- Brings arm forward and across the chest Deltoid- Brings arm away from the side of body; moves arm up and down in front. Trapezius- raises scapula, as when shrugging shoulders; pulls head backward. biceps brachii- bends forearm at elbow triceps brachii- straightens forearm at elbow. External oblique- compresses abdomen; rotation of trunk latissimus dorsi- Brings arm down and backward behind the body. gluteus maximus- extends thigh back quardriceps femoris- straightens leg at knee; raises thigh gastrocnemius- turns foot downward, as when standing on toes; bends leg at knee.

4. Define myofibrils, sarcomeres, myosin, actin Myofibrils- contractile portions of the muscle fibers. Sacromeres- extends between two dark lines and contains two types of protein myofilaments. The thick filaments are made up of proteins called myosin, and the thin filaments are made up of protein called actin. 5. Describe the structure of a sarcomere's thick and thin filaments. The thick filament is composed of hundred molecules of myosin and is shaped like a golf club. The thin filament consists of two intertwining strands of the protein actin. 6. Describe the sliding filament model and insert image (How does the sarcomere contract?) The movement of actin filaments in relation to myosin filaments of muscle contraction.