1. Weight and Work Skeletal Muscle

2. Definitions Motor Unit: a motor neuron and all muscle fibers it innervates. Twitch: single contraction in response to a single stimulus/AP. Isotonic: muscular contraction where constant tension continues while the length of the muscle changes. – Concentric – Eccentric Isometric: muscular contraction against resistance in which the length of the muscle remains the same.

3. Isotonic Contraction

5. Isometric Contraction

7. Work Work is accomplished only when an object is moved. Work = Force X Distance Force = muscle tension required to overcome the load (weight of the object). In an isometric contraction where no object is moved (muscles do not change length) the work done = zero.

8. Load/Velocity relationship Load is an important determinant of shortening velocity. Load = velocity

9. Load/Velocity Relationship

10. 3 Muscle Fiber Types Slow OxidativeFast OxidativeFast Glycolytic Postural musclesBird flight muscles Mammal breast muscles

11. Lithobates pipiens Referred to as Rana pipiens also. Opportunistic feeders Occurs through much of US and Canada (cosmopolitan) Status is controversial: widespread, but most populations throughout range are decreasing rapidly. Commonly used in research.

12. HOMEWORK!!!! Write an entire lab report, again. Include answers to ALL labscribe questions WITHIN the body of the paper. Follow my formatting instructions!!!!!! Due on November 28/29.

13. Next Week… Have a GREAT Thanksgiving!!!