1. Muscle contraction Public domain image

2. Muscle has two purposes Generate motion Generate force

3. 3 Muscle types Skeletal Cardiac Smooth Striated

4. Striated vs Smooth muscle http://biodidac.bio.uottawa.ca/thumbnails/filedet.h tm?File_name=B33-8F&File_type=GIF http://biodidac.bio.uottawa.ca/thumbnails/filedet.ht m?File_name=19-51&File_type=GIF Images from BIODIDAC

5. What is meant by involuntary muscle?

6. Gross structure Image from National Cancer Institute http://training.seer.cancer.gov/anatomy/musc ular/structure.html

7. Skeletal muscle Is an organ –Composed of connective tissue, muscle, blood vessels and nerves Muscle fibers have a variety of important structures –Sarcolemma, t-tubules, sarcoplasm, multiple nuclei, Sarcoplasmic reticulum, myofibrils, mitochondria, Myofibrils are important in contraction and composed of a variety of proteins –Troponin, tropomyosin, titin, nebulin –Actin and myosin are the contractile proteins

8. Myofibril and the Sarcomere Arrangement of thick and thin filaments creates a repeating pattern of alternating light and dark bands. One repeat is a sarcomere Image Source: http://en.wikipedia.org/wiki/File:Myofi bril.svg

9. Banding patterns Image Source: http://en.wikipedia.org/wiki/File:Sarcomere.svg

10. Sliding filament theory of contraction overlapping actin and myosin filaments of fixed length slide past one another in an energy-requiring process, resulting in muscle contraction.

11. When contraction happens what happens to the size of the I band? Image Source: http://en.wikipedia.or g/wiki/File:Sarcomere.svg

12. Titin and Nebulin Image Source: http://en.wikipedia.org/wiki/File:Sarcomere.svg

13. Image author: Moralapostel Power Stroke Image source: http://en.wikipedia.org/wiki/Myosin

14. Regulatory proteins Original drawing by RMB Hoffman (Copyleft 2010). Based on Proteins 2008 Nov 1;73(2):338-50. Image source: http://en.wikipedia.org/wiki/File:Troponin-activation.png

15. Muscle contraction can’t happen without ATP! ATP binds and myosin detaches from actin. ATP hydrolysis occurs, myosin lightly attaches to actin. Energy released allows the myosin to change confirmation and have the power stroke.

16. Excitation-contraction coupling and relaxation Which second messenger is important to this process?

17. T-tubules are next in the pathway Action potential is propagated through T- tubules. Image source BIODIDAC: http://biodidac.bio.uott awa.ca/thumbnails/file det.htm?File_name=B 32- 5J1&File_type=GIF

18. The sarcoplasmic reticulum has a high concentration of this second messenger, which it releases at this point. What is the second messenger?? (Not on your worksheet) Image Source BIODIDAC: http://biodidac.bio.uottawa.ca/t humbnails/filedet.htm?File_na me=CELL018B&File_type=GI F

19. Calcium Binds to troponin and tropomyosin releases its inhibition on actin-myosin interactions. Image Author: Daniel Schwen Source: http://en.wikipedia.org/wiki/File: CH_cow_2.jpg

20. Calcium concentrations then decrease It is brought into the Sarcoplasmic reticulum (SR) How does this happen?? (the concentration of calcium is lower in the cytoplasm than it is in the SR)

21. Dissociation of Ca 2+ leads to… Restoration of tropomyosin activity.

22. Excitation-contraction coupling and relaxation Acetylcholine release from the motor neuron triggers Na + entry into the muscle initiating an action potential. T-tubules Ca ++ entry from the Sarcoplasmic reticculum Ca ++ binds to troponin, actin-myosin interaction is allowed. Power stroke Sliding filaments and contraction

23. Create a graph based on the data on your worksheet and answer the questions which follow