Understanding Muscle Physiology: Contraction Mechanism and Energy Systems

1. Muscle Tissue 2 Muscle Contrations

2. The Sliding Filament Theory • The thin filaments (actin) slide over the thick causing the sarcomere to shorten. This process requires ATP

4. Mechanism of Filament Sliding Animation • http://www.blackwellpublishing.com/matthews/myosin.html

5. Neuromuscular Junction • Where a muscle is innervated -OR- • Place where a nerve meets a muscle

6. Neuron • Nerve Cell

7. Motor Neuron • The nerve that stimulates a muscle to contract

8. Motor End Plate • Axon of a motor neuron that attaches to the sarcolemma of the muscle fiber  Motor End Plate Muscle   Neuron

9. Motor Unit • The combination of the motor neuron and the muscle it innervates

11. Physiology of Contraction • An action potential causes the release of Ca+2 ions stimulating the myosin to move the actin filament • http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/muscles/muscles.html • (labeling picture)

12. Muscle Contraction Summary • http://bcs.whfreeman.com/thelifewire/content/chp47/4702001.html • Narrated Summary with tabs

13. Energy for Contraction • The body uses ATP for energy • This ATP can be produced by the body in 3 ways

14. Phosphagen System • ADP + P + Energy  ATP • Fast • Not a lot of energy

15. Anaerobic System • 1C6H12O6 2C3H6O3 + ATP • Glucose is broken down into Pyruvic Acid • Needs no oxygen • Not a lot of ATP

16. Aerobic System • 1C3H6O3 + O2 CO2 + H2O + ATP • Starts with Pyruvic Acid from Anaerobic • Needs Oxygen to take place • Makes a lot of energy • Many Steps - longest

17. What Happens When You Exercise • The muscle cells burn off the ATP they have floating around in about 3 seconds. • The phosphagen system kicks in and supplies energy for 8 to 10 seconds. This would be the major energy system used by the muscles of a 100-meter sprinter or weight lifter, where rapid acceleration, short-duration exercise occurs. • If exercise continues longer, then the glycogen-lactic acid system kicks in. This would be true for short-distance exercises such as a 200- or 400-meter dash or 100-meter swim. • Finally, if exercise continues, then aerobic respiration takes over. This would occur in endurance events such as an 800-meter dash, marathon run, rowing, cross-country skiing and distance skating.

19. All or None Principle • When a muscle fiber is stimulates it either completely contracts or does not contract at all

20. Threshold Stimulus – the weakest stimulus that can cause a muscle to contract • Sub-Threshold Stimulus – a stimulus that is too weak to cause a contraction

22. Myogram • A record of the electrical activity of a muscle to determine the type of contraction

23. Twitch • A rapid, jerky response to a single stimulus

24. Latent Period – time between the application of the stimulus and the muscle contraction • Contraction Period – time when filament are sliding over each other, causing a contraction • Relaxation Period – Time during which filaments are sliding back into place • Refractory Period – Time following a contraction during which a muscle is unable to respond to a stimulus

25. Refractory Period Contraction Period Relaxation Period Latent Period

26. Tetanus • A sustained contration

27. Treppe • A muscle contracts more forcefullu after contracting several times

28. Isotonic • Tension remains constant but the muscle shortens • Lifting

29. Isometric • Tension increases but muscle does not shorten

30. Muscle Tension • The force of a muscle contraction

31. Muscle Tone • State of partial contraction – muscle is tight but not causing movement

32. Muscular Atrophy • Wasting away of muscle

33. Muscular Hypertrophy • Increase in the size of muscle fibers