2. terminal cisternae Terminal cisternae of sarcoplasmic reticulum (the “blue” tubes) Transverse tubules (the “purple” tubes) Myofibril Sarcolemma 2. The depolarization wave (“signal”) then follows the surface of the transverse tubules which brings the “signal” (depolarization wave) deep inside the muscle fiber and parallel to the terminal cisternae of the sarcoplasmic reticulum . T-tubule opening
25. 3. After the “signal” has completely depolarized the sarcolemma, it enters the sarcoplasmic reticulum . The sarcoplasmic reticulum does not have an “ internal ” environment and an “ external ” environment (like the sarcolemma), since it is contained completely within the muscle fiber.
26. 4. The sarcoplasmic reticulum does contain Ca +2 ions (calcium ions) however, and when the depolarization wave hits the sarcoplasmic reticulum it releases the Ca +2 ions into the sarcoplasm . Thus, there is a continuation of moving charged particles!
27. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
28. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
29. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
30. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
31. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
32. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
33. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
34. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
35. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
36. Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2 Ca +2
37. 5. Chemical cross bridges form between actin and myosin within the sarcomeres whenever Ca +2 ions are released into the sarcoplasm.
38. 6. These cross bridges “ jump ” or “ ratchet ” down the myosin thus sliding the actin over the myosin .
39. 7. This causes the sarcomere to shorten , thus the muscle is contracted .