1. CARDIOVASCULAR SYSTEM THE HEART Chapter 18

2. Overview of Cardiovascular System

3. Location of the Heart

4. Pericarium

8. Coronary Circulation Anastomoses

13. Cardiac Muscle

15. Autorhythmic cells initiate depolarization Na + influx (depolarization) goes down T-tubules depolarization opens slow Ca channels Ca 2+ influx  release of Ca 2+ from sarcoplasmic reticulum Ca 2+ binds troponin  cross bridging of sliding myofilaments Ca 2+ surge across membrane prolongs depolarization (plateau)  increases duration of contraction K + channels open and repolarize sarcolemma Excitation Contraction Coupling

16. Cardiac Muscle: Energy Requirements More mitochondria than skeletal muscle; – Higher dependence on O 2 Cardiac muscle readily adapts to available fuel sources O 2 deficit is the cause of system failure with decreased blood flow

17. Heart Physiology: Electrical Intrinsic conduction system –Specialized cells that initiate & distribute impulses –Autorhythmic cells of nodes & conducting pathway have unstable resting potential & have the capability of spontaneous depolarization