Musculoskeletal System Skeletal Muscle attached to bone responsible

Musculoskeletal System

Skeletal Muscle: • attached to bone • responsible for body movements • can be controlled voluntarily • has a hierarchical structure of fibers within fibers

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Skeletal Muscle Cells Structures: • Long, narrow cells • Filled with specialized cytoskeleton fibers • Many mitochondria • Many nuclei along edges of cell Functions: Ø Reach the whole length of a muscle Ø Fibers attach and slide past each other to contract Ø Provide ATP energy for cytoskeleton to move Ø Help make cytoskeleton proteins along the length of the whole cell

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Animations: Overview, zoom in, and sarcomere contraction in grasshopper muscles: • http: //entochem. tamu. edu/Muscle. Struc. Contractswf/index. html Simultaneous whole-muscle, cartoon sarcomere, and real muscle fiber contraction: • http: //www. edumedia-sciences. com/en/a 502 -muscle-contractionsarcomere Actin, myosin, and cross-bridges: • http: //highered. mcgrawhill. com/sites/0072495855/student_view 0/chapter 10/animation__sar comere_contraction. html

How Muscle Cells Contract 1. Cytoskeleton fibers attach to each other and pull together. 2. This makes the entire muscle cell get shorter (aka contract). 3. This process uses a lot of ATP energy (provided by mitochondria). 4. When the fibers let go, the muscle relaxes.

Muscle Contraction Creates Body Movements · Muscles are attached to at least two points: · moveable bone · immovable bone · When muscles contract, bones change position Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscles Work in Opposing Pairs Upper Arm: • Biceps contract Arm bends at the elbow • Triceps contract Arm straightens Lower Leg: • Shin muscle contracts Foot goes up • Calf muscle contracts Foot goes down

Preview of This Week’s Lab: Chicken Wing Dissection!