1. Muscle Contraction

3. Motor Unit Motor neuron + all controlled muscle fibers
Neuromuscular junctions
Connected fiber amounts vs. force produced

4. Muscle Contraction
Step 1: Action potential moves down motor
neuron.

5. Step 2: Acetylcholine (Ach) is released from synaptic vesicles.
Step 3: Ach binds to sites on sarcolemma

6. Muscle contraction
Step 4: Action potential moves down T-tubules to sarcoplasmic reticulum.

7. Stimulation of Skeletal Muscle

8. Step 5: Ca+ released. Ca+ binds to troponin causing it to change shape
Step 5: Ca+ released. Ca+ binds to troponin causing it to change shape. Shape change releases it from tropomyosin (blocker).
Step 6:
Tropomyosin moves to
reveal binding sites on
actin (thin filament).

9. Step 7: Myosin (thick filament) + ATP attaches to actin.
Step 8: Myosin heads move actin toward center of A band (power stroke)

10. Sliding Filament Hypothesis
Hyperlink to SFH video:

12. Muscular Contraction
Step 9: ATP (energy) or Ca+ is gone, myosin detaches.
Step 10: Contraction over
Ca is pumped back to the SR
Troponin reattaches
Tropomyosin reattaches
Binding sites covered = RELAXATION

13. Slow-Twitch vs Fast-Twitch Muscle Fibers
Distance runner - aerobic respiration
Slow-Twitch vs Fast-Twitch Muscle Fibers
Sprinter- anaerobic glycolysis

14. Isometric and Isotonic Contractions
Concentric
Eccentric