Muscular+System+Questions+SLS

September 29, 2008 Science-Human Bio**
 * Shelby Smith


 * Muscular System Chapter 12 pp 227-236 (New Unit called Move it)**

The smooth muscle are single nucleus cells, which are usually arranged in parallel lines which form sheets. Smooth muscle is located in the walls of hollow internal organs, and it causes the walls to contract. Next, the cardiac muscle forms the heart walls, and they are single nucleus cells which contract and relax at set intervals. Lastly, skeletal muscles are tubular, and multinuclear. They make up the skeleton muscles and they run the length of the muscle and can be long, with voluntary movement and contraction.
 * 1. What are the three types of muscles in the body and what is the function of each?**

Skeletal muscles work in pairs and each general muscles is linked to the movement of one bone. Skeletal muscles are made up of fascia and tendons, which sometimes extend past the bone. The skeletal muscles usually function in groups, and the nervous system stimulates this. Muscles can only pull, so that is how they move bones through opposite movements.
 * 2. How do skeletal muscles work together to cause the bones to move?**

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 the body; moves arm up and down in front. Trapezius: Raises scapula, as when shrugging shoulders; pulls head backwards. biceps brachii: Bends forearm at the elbow. triceps brachii: Straightens forearm at elbow. External oblique: Compression of abdomen, rotates the trunk. Latimuss Dorsi: Brings arm down and backward behind the body. gluteus maximus: Extends back thigh. quardriceps femoris: Straightens leg at knee, raises thigh. Gastrocnemius: Turns foot downward, as when standing on toes; bends leg at the knee. Myofibrils are the contractile portions of muscle fibers. Sacromeres contain two types of protein myofilaments, also they are units of myofibrils. Myosin is the thick filament of proteins in the sacromeres, and the actin is the thin filaments in the sacromeres.
 * 3. Insert an image of the major muscles in the body like the one on page 231.**
 * 4. Define myofibrils, sarcomeres, myosin, actin.**

The thick filament is made up of several hundred molecules of the protein myosin. Each myosin is shaped like a golf club with the head ending the molecule. The cross-bridge, or head of the ‘golf club’, occurs on each side of the sacromere but not the center. The thin filament consists of intertwining strands of the protein actin. The two other proteins are called tropomyosin and troponin.
 * 5. Describe the structure of a sarcomere's thick and thin filaments.**

The sliding filament is the movement of actin filaments in relation to myosin filaments. The sacromere shortens. The ATP supplies the energy for muscle contraction. Although it is the actin filaments that slide past the myosin, it is the latter that is doing the work. The myosin breaks down the ATP, and their cross-bridges pull the actin filaments toward the center of the sacromere.
 * 6. Describe the sliding filament model and insert image (How does the sarcomere contract?)**