1. Seminar 6 The Muscular System

2. Introduction  Muscular tissue enables the body and its parts to move Movement caused by ability of muscle cells (called fibers) to shorten or contract Muscle cells shorten by converting chemical energy (obtained from food) into mechanical energy, which causes movement Three types of muscle tissue exist in body

3. 3 Types of muscle  Skeletal  Cardiac  Smooth

4. Structure and Function  Cardiac: involuntary; heart  Smooth: involuntary; linings  Skeletal: voluntary; attaches to bone

5. Functions of muscle?  Movement  Posture  Heat production  Let’s discuss how…

6.  Movement  How does this help us?

7. Movement  Biceps brachii – synergist  Triceps brachii - antagonist

8. Posture  Posture or muscle tone

9.  Heat Production

10. Heat Production  Requires ATP  Contraction of muscle fibers produces heat  How relevant is this function???

11. Muscle Tissue  Function — all muscle cells specialize in contraction (shortening)  Contraction requires: Stimulus (nerve)  Muscle fiber  Calcium  ATP  Chemical rxn  No stimulus Must occur in EACH muscle fiber All-or-none

12. Figure 7-3, page 158

14. The Step Test

15. Step Test  Which type of muscle tissue is being used in this test? Answer the poll question ---

16. Step Test, con’t  Why do breathing and heart rate remain elevated after exercise stops?

17. Step Test, con’t  Why would a “physically fit” person return to normal breathing and heart rate levels more quickly than an unfit person?

18. Step Test, con’t  increased efficiency of the respiratory and circulatory systems  an increase in the number of blood vessels in muscles  more efficient delivery of oxygen and glucose to muscle fibers  more oxygen is available = the less “oxygen debt” there will be in the muscles.

19. Step Test, con’t  Aerobic training also increases the number of mitochondria in muscle fibers.  Why would this benefit the muscle contraction process?

20. Step Test, con’t  Mitochondria are cellular organelles that convert glucose to ATP  Contraction of muscle cells requires ATP  Increase in the number of mitochondria in a muscle cell increases the speed with which ATP is produced in the cell. Mitochondria = ATP rate

21. Step Test, con’t  http://www.health.harvard.edu/newsweek/Aer obic_Fitness_Test_The_Step_Method.htm

22. Time for Q and A!  Do you have any questions?