1. Human Body Systems Lesson 21 Terms and Definitions

2. Q: Why do muscles get tired?

3. Muscle Fatigue Muscle Fatigue – the reduced ability of a muscle to contract. http://run4change.files.wordpress.com/2009/04/exhuasted-runner1.jpghttp://shakeout.files.wordpress.com/2008/11/tired_runner.jpg

4. Muscle Fatigue Why? 1.Muscles need energy (ATP) from cellular respiration 2.Fatigue happens when… ATP produced cannot keep up with ATP needed by muscles

5. Light exercise Aerobic respiration can produce most of the ATP energy needed for light exercise. When there’s not enough Oxygen present, Anaerobic Respiration occurs. –Lactic acid builds up, causing fatigue –Lactic acid is washed out of muscles within 30 minutes after exercise.

6. Muscle Fatigue Avoid fatigue by training and practicing.

7. Slow Twitch Muscles Muscle fibers are slow to contract Endurance More mitochondria, more myoglobin –Myoglobin – reddish protein that stores O 2 and gives muscle fibers color. Found in Athletes that sustain a moderate level of activity for extended periods of time. Ex. Cyclist, marathon runners, etc. http://z.about.com/d/bicycling/1/0/6/1/-/-/71398008.jpg

8. Fast Twitch Muscles Fibers contract rapidly Fewer Mitochondria, Less myoglobin Found in: athletes that do rapid activites. Ex. Weight lifters, sprinters. http://www.baspeed.com/userfiles/sports/lianalambert%20weightlifter.jpg

9. FastSlow Chickens/TurkeyDucks White/Light meatDark meat Don’t flyFly A LOT! Fast Twitch FibersSlow Twitch fibers Less enduranceLots of endurance Less myoglobinMore myoglobin

10. A CRAMP!!! AAAAHHHHH A MUSCLE CRAMP!!!

11. A cramp Cramp – a sustained muscle contraction of a muscle group. –WHEN: during/following exercise/NO apparent reason. –CAUSES: could be low blood sugar, electrolyte depletion (sodium/calcium), and dehydration

12. Q: How do muscles contract?

13. Muscle Contractions 1.Nerve sends a signal to muscle 2.Actual Contraction (2/3’s its size). 3.Relaxation Contraction takes approx. 10-100 milliseconds!!