1. Skeletal Muscle Lab

2. Three Muscle Types

4. Parts of the Muscle Fiber

5. Steps in Muscle Contraction  Motor neuron releases acetylcholine which diffuses across synaptic cleft, binds to ACh receptors  Muscle fiber is stimulated to make its own electrochemical impulse  SR releases Calcium  Calcium binds to troponin, moving tropomyosin away to expose cross- bridge binding sites on actin  Myosin head splits ATP and can bind to actin…

6. Sliding filament mechanism of muscle contraction Muscle Contraction Movie!

7. Strength of contraction depends on the number of motor units that are stimulated

8. Part 1: Glycerinated Fibers Rabbit muscle strips with ions and ATP removed and troponin/tropomyosin complex disrupted. What things would be necessary for muscle contraction to occur?

9. Part 2: Force of Contraction Force Transducer—measures the force you are exerting as you pull on the handle. EMG Sensor—measures the motor unit activity involved with your muscle contraction (muscle action potential).

10. Part 2: Force of Contraction Varied Strength—measure average force & action potential for different levels of force. Fatigue—what happens to the force & action potential after applying near-maximal force for a long period of time? Latency—what is the difference between the time the action potential increases & the time the force increases?