The document summarizes key aspects of heart physiology, including: - The heart generates blood pressure, routes blood flow between the pulmonary and systemic circuits, and ensures one-way blood flow through valves. - The cardiovascular system consists of the pulmonary circuit carrying blood to and from the lungs, and the systemic circuit carrying blood to and from the rest of the body. - The left side of the heart is more muscular than the right side to pump blood through the higher pressure systemic circuit.

1. Physiology of the Heart Dr. George Pearce

2. Functions of the Heart Generating blood pressure Routing blood: separates pulmonary and systemic circulations Ensuring one-way blood flow: valves Regulating blood supply Changes in contraction rate and force match blood delivery to changing metabolic needs

3. The cardiovascular system is divided into two circuits Pulmonary circuit blood to and from the lungs Systemic circuit blood to and from the rest of the body Vessels carry the blood through the circuits Arteries carry blood away from the heart Veins carry blood to the heart Capillaries permit exchange

5. Structural Differences in heart chambers The left side of the heart is more muscular than the right side Functions of valves AV valves prevent backflow of blood from the ventricles to the atria Semilunar valves prevent backflow into the ventricles from the pulmonary trunk and aorta Heart chambers and valves

7. Cardiac Muscle Contraction Heart muscle: Is stimulated by nerves and is self-excitable Cardiac muscle contraction is similar to skeletal muscle contraction

8. Conducting System of Heart

9. Heart Physiology: Sequence of Excitation Sinoatrial (SA) node generates impulses about 75 times/minute Atrioventricular (AV) node delays the impulse approximately 0.1 second Impulse passes from atria to ventricles via the atrioventricular bundle (bundle of His) to the Purkinje fibers and finally to the myocardial fibers

10. Impulse Conduction through the Heart

11. An Electrocardiogram

12. ECGs, Normal and Abnormal

13. ECGs, Abnormal Arrhythmia: conduction failure at AV node No pumping action occurs

14. Factors Affecting Cardiac Output Figure 20.20

15. Heart Rate Pulse = surge of pressure in artery infants have HR of 120 bpm or more young adult females avg. 72 - 80 bpm young adult males avg. 64 to 72 bpm HR rises again in the elderly

16. Preload and Afterload Figure 18.21

17. Effects of Hormones on Contractility Epi, NE, and Thyroxine all have positive ionotropic effects and thus  contractility Digitalis elevates intracellular Ca ++ concentrations by interfering with its removal from sarcoplasm of cardiac cells Beta-blockers ( propanolol, timolol ) block beta-receptors and prevent sympathetic stimulation of heart (neg. chronotropic effect)

18. Exercise and Cardiac Output Proprioceptors HR  at beginning of exercise due to signals from joints, muscles Venous return muscular activity  venous return causes  SV  HR and  SV cause  CO Exercise produces ventricular hypertrophy  SV allows heart to beat more slowly at rest  cardiac reserve

19. Factors Involved in Regulation of Cardiac Output