1. Week 1 Click images for hyperlinks!

2. What is a muscle? Muscles are organs made of muscular and connective tissues, which make up the Muscular System They attach to bones and other muscles so that when they contract, they produce motion There are three different types of muscle: Skeletal Cardiac Smooth

3. Muscle Tissue Muscle tissue: Collection of muscle cells which contain sarcomeres Sarcomere: a single contractile unit made of primarily actin, myosin, and titin

4. Sarcomere M-line Only myosin Doesn’t move Z-disk Perimeter of sarcomere Moves toward M-line with contraction I-band Actin + titin Spans width of titin Shrinks with contraction A-band Actin + myosin Spans width of myosin H-zone Only myosin Gets smaller with contraction Actin Myosin

5. Sarcomere Proteins Actin G-actin: Globular individual pearl-like actin molecules F-actin: G-actin pearls assemble into a Filament of actin Myosin pulls actin inward Contains head and tail units Myosin head binds to actin, pulls it inward to contract Titin pushes z-discs outward Elastic, holds myosin in place and helps re-extend sarcomere upon relaxation

6. Video- Sarcomere Contraction Click video to watch

7. Arrangement of Fibers Many sarcomeres together make up a myofibril Many myofibrils make up a muscle fiber (cell) Coated by endomysium Many fibers make up a fiber bundle Coated by perimysium Many bundles make up the entire muscle Coated by epimysium

8. Types of Muscle Smooth *Found in organs (GI, vessels) for constriction -Involuntary -Non-striated -Mononucleate -Parallel fibers Cardiac *Only in the heart for moving blood -Involuntary -Striated -Mononucleate -Branched Fibers -Intercalated Discs Skeletal *Connected to muscle for voluntary motion -Voluntary -Striated -Multinucleate -Parallel fibers

9. Types of Muscle

10. Next Week- A Preview