1. Heart

2. Location Within the thorax Pointed APEX extends to left Rests on diaphragm at the 5 th intercostal space Broad BASE, lies under the 2 nd rib

5. Pericardium A double membrane sac encloses heart thin visceral pericardium = epicardium hugs the surface of the heart loose outer layer = parietal pericardium

7. Pericardial Fluid Slippery lubricating fluid produced by the membrane between the pericardial layers. It allows the heart to beat in a frictionless environment

8. Myocardium Heart walls are thick cardiac muscle

9. Chambers 4 hollow chambers Lined with thin lining called endocardium

10. Atria 2 superior RECEIVING chambers Thin walled Blood flows into and fills the atria under low pressure

12. Ventricles 2 inferior DISCHARGING (pumping) chambers Thick walled Forces blood out of the heart into large arteries

13. A Septum divides the heart longitudinally Interatrial Septum Interventricular Septum

14. Double Pump Pulmonary circulation to lungs and back Systemic circulation to body tissue and back

16. Pulmonary Circulation Right side of the heart  lungs  left side of the heart

17. Systemic Circulation Left side of the heart  Body Tissue  Right side of the heart

18. Valves 4 valves allow blood to flow in only one direction Prevent backwash 2 AV valves = atrioventricular valves 2 Semilunar valves

20. AV valves Between atria and ventricle Prevent backwash into atria Left AV = bicuspid or mitral (2 flaps) Right AV = tricuspid (3 flaps)

21. The AV valves are anchored to the wall of the ventricles by the Chordae Tendineae Valves are open when ventricle is relaxed closed when ventricle is contracted

22. Semilunar valves Guard the base of the large arteries leaving the ventricles Each valve has 3 cusps (flaps) When ventricles contract, they open, when relaxed they close to prevent backwash

23. Pulmonary semilunar- from the right ventricle to the pulmonary trunk (Artery) Aortic semilunar- from the left ventricle to the aortic artery

24. Each set of valves open at different times: AV opens when ventricle relaxes Semilunar opens when ventricles contract

25. Oxygen Poor Blood From the veins of the body tissue  Superior and Inferior Vena Cava  Right atria  tricuspid valve  Right ventricle  pulmonary semilunar valve  Pulmonary Trunk  Pulmonary arteries  (branch right and left)  lungs  picks up oxygen and dumps off carbon dioxide

26. Oxygen Rich Blood Drained from the lungs  4 Pulmonary Veins  Left atria  bicuspid valve  Left ventricle  aortic semilunar valve  Aorta  body tissues  dumps off oxygen and picks up carbon dioxide

27. Cardiac Circulation Although the heart chambers are filled with blood almost continuously, that blood does NOT nourish the myocardium

28. The right and left coronary arteries branch from the base of the aorta and encircle the heart in a groove at the junction of the atria and ventricles

29. Those arteries are compressed when the ventricles contract and are only able to supply blood to heart muscle between beats

30. Rapid heart rate may cause inadequate blood supply The lower your resting heart rate, the better nourished your heart muscle is

31. The myocardium is drained by the coronary veins  coronary sinus  the right atrium

32. Cardiac Cycle The time and events occurring from one heartbeat to the next

33. Systole = contraction Diastole = relaxation

34. Lub – Dup - Pause “lub” – closing of the AV valves- longer and louder – ventricles contracting “dup” – closing of semilunar valves – shorter and sharper- ventricles relaxing “pause” is the heart in complete relaxation Murmurs are usually problems with the valves leaking

35. Atria contract simultaneously As they begin to relax  the ventricles contract (ventricular systole)  ventricles relax (ventricular diastole)

37. Conduction System Cardiac muscle cells can contract spontaneously and independently 2 types of control systems: -Intrinsic -Extrinsic

39. Intrinsic -Purkinje or Nodal system -A cross between nerve and muscle tissue -Auto-rythmic cells -Can initiate action potentials or trigger contractions

40. SA Node SA = sinoatrial On the right atrial wall PACEMAKER – starts each beat

41. AV Node Atrioventricular On interatrial septum Bundle of His  Bundle branches  Purkinje fibers  Ventricles contract

42. Extrinsic System Heart contractions can be changed by autonomic nerves, chemicals, hormones, and ions (Na+, potassium, Calcium) Stress (sympathetic influence) affects SA node which increases heart rate