Physiology

1. Objective
Discuss the process of excitation –
contraction coupling

2. The process by which depolarization of
the muscle fiber initiates contraction is
called excitation–contraction coupling

3. Process..
 Generation of action potential in muscles fiber
 Inward spread of depolarization along T-tubules into
the muscle
 Release Calcium from the terminal cisternae

5.  Increasing Sarcoplasmic Ca2+ concentration
 Binding of Ca2+ to troponin-C that uncover the
myosin binding sites on Actin
 Attachment of myosin head to actin initiating
cross-bridge cycle

8. Contd…
 Sliding of thin filament over thick filament towards
the center of the sarcomere
 Decrease sarcomere length producing muscle
shortening
 Contraction

10. Relaxation
 Ca2+ pumped back into sarcoplasmic reticulum
 Released of Ca2+ from troponin
 Cessation of interaction between actin and myosin

11. summary

13. Reference
 Guyton and Hall-Textbook of medical physiology-
13th edition
 Understanding Medical Physiology-4th edition
 Ganong’s Review of Medical physiology-23th edition