Understanding Muscle Anatomy and Function

1. Mader Chapter 7 1-5 on page 133 Muscle Study Questions

2. 1. Name & describe the 3 types of muscles, & give a general location for each type (p. 111) • Skeletal – voluntary (attached to skeleton) • Cardiac – involuntary (heart) • Smooth – involuntary (walls of hollow internal organs)

3. 2. List & discuss 4 functions of muscles. (p 111) • Produce movement – picking up an object • Resist movement – posture, blood pressure (Newton’s 3rdLaw: muscles generate a force (static tension) that exactly opposes and equal but opposite force being applied to a body part • Generate heat – contraction of our muscles accounts for > 75% of all heat generated by the body – shivering thermogenesis • Stabilizing joints – stabilize & strengthen

4. 3. Describe the anatomy of a muscle, from the whole muscle to the myofilamentsw/in a sarcomere. Name the layers of fascia that cover a skeletal muscle & divide the muscle interior. (p 113) • A group of many individual cells, all w/same origin and insertion and all with the same function (p. 115) • Arranged in bundles called fascicles • Each bundle is enclosed in a sheath of fibrous connective tissue called fascia • Each fascicle contains 12 to 1000s of individual muscle cells – called muscle fibers • The outer surface of the whole muscle is covered with several more layers of fascia – at the ends all come together forming tendons

5. Muscle Cells to sarcomere • Tube shaped 3 cm – 30 cm (thigh) • Can contain more than one nucleus just under the cell membrane (skeletal) • Nearly entire cell is packed with long cylindrical structures in parallel called myofibrils • Myofibrils are packed with contractile proteins called actin and myosin • When myofibrils contract the muscle cell also contracts

6. Myofibrils = muscle fibers • Each skeletal muscle fiber is a long, cylindrical cell w/multiple oval nuclei just beneath the sarcolemma (plasma membrane) surface • Fibers are large, 10 to 100 m in diameter, and up to hundreds of centimeters long • Sarcoplasm, similar to cytoplasm of other cells, but has numerous glycosomes (=organelle full of glycogen) and a unique oxygen-binding protein called myoglobin, similar to hemoglobin

8. Sarcomere = contractile unit (6)sarco – Gk for “flesh”

9. Sarcomere / contractile unit (6) • A single myofibril within one muscle cell (in your biceps) can contain > 100,000 sarcomeres arranged end to end. • 100,000 sarcomeres all shortening at once produces a muscle contraction • Understanding muscle shortening is simply understanding how a single sarcomere works

10. Sarcomere = contractile unit From Z to shining Z

11. Sarcomerestructure • 2 kinds of proteins • Myosin – thick filaments interspersed @ regular intervals with a different protein • Actin – thin filaments that are structurally linked to the Z-line • Myosin filaments are completely contained within the sarcomere • Muscle contractions depend on the interaction of these 2 filaments

15. 4. List the sequential events that occur when a nerve impulse reaches a muscle. • Nerves activate skeletal muscles • Activation releases calcium • Calcium starts the sliding filament mechanism • Contraction ends when nerve activation ends • Sliding filament model of contraction

17. http://video.google.com/videosearch?ndsp=18&um=1&hl=en&q=sliding%20filament%20of%20contraction&ie=UTF-8&sa=N&tab=iv#http://video.google.com/videosearch?ndsp=18&um=1&hl=en&q=sliding%20filament%20of%20contraction&ie=UTF-8&sa=N&tab=iv# • grants.hhp.coe.uh.edu/clayne/6397/Unit3.htm

18. 5. How is ATP supplied to muscles? What is oxygen debt? (p. 114) • Lots of mitochondria form ATP by aerobic cellular respiration • Muscles contain creatine phosphate (high E storage supply) used to regenerate ATP indirectly • ATP produced anaerobically when oxygen supply is limited

19. Oxygen Debt • Continued intake of oxygen (panting) to complete the metabolism of lactic acid (built up anaerobically) • Lactic acid is transported to the liver and broken down into carbon dioxide and water