Anatomy of the Cardiovascular System

1. Anatomy of the Cardiovascular System

2. Cardiovascular System • Also circulatory system • Consists of: the heart, arteries, veins, capillaries

3. Heart • Four chamber muscular organ • Comparable to the size of a closed fist • Located in the mediastinum • Behind sternum • Between 2nd and 6th ribs • Between T5-T8 • Apex – base of heart • Located at the 5th intercostal space

4. Heart

5. Coverings of the Heart • Pericardium – loose fitting sac surrounding the heart • Fibrous pericardium – tough, loose-fitting, inelastic • Serous pericardium • Parietal layer: lines the inside of the fibrous pericardium • Visceral layer: adheres to outside of the heart • Pericardial space: between parietal and visceral layer • Filled with 10-15mL of pericardial fluid • Decreases friction

6. Walls of the Heart • Epicardium – outer layer • Epicardium = serous pericardium • Myocardium – thick, contractile layer composed of cardiac muscle cells • Intercalated disks contain many gap junctions • Allow cardiac muscle cells to function as a single unit  syncytium • Endocaridium – interior of cardiac wall • Endothelial tissue • Covers projections of myocardial tissue called trabeculae

7. Walls of the Heart

8. Chambers of the Heart • Atria – two superior chambers • “Receiving chambers” • Blood from veins enters atria • Ventricles – two inferior chambers • “pumping chambers” • Thick muscular walls to increase force of pumping action • Left > right • Separated by interventricular septum

9. Valves of the Heart • Permit blood flow in one direction during circulation • Atrioventricular valves (AV valves) • Also cuspid valves • Between atria and ventricles • Semilunar (SL valves) • Between R ventricle and pulmonary arteries and L ventricle and aorta

10. Atrioventricular Valves • Tricuspid valve • Btwn R atrium and ventricle • 3 flaps of endocardium • Connected to ventricular papillary muscle via chordae tendinae • Bicuspid valve • Btwn L atrium and ventricle • Also called mitral valve • Two flaps of endocardium

11. Semilunar Valves • Pulmonary semilunar valve • Btwn R ventricle and pulmonary trunk • Aorta semilunar valve • Btwn L ventricle and aorta

12. Chambers & Valves Trace the blood flow through the heart

13. Blood Supply to the Heart • Right and left coronary arteries • First branches off aorta • Right coronary artery  right marginal artery & posterior interventricular artery • Left coronary artery  circumflex artery & anterior interventricular artery • Most of the blood goes to the L ventricle • In 50% of the population, the R coronary artery is dominant

14. Blood Supply to the Heart • Anastomosis: Connections between blood vessels that allow for collateral circulation • Few exist between large branches of coronary arteries • In presence of an obstruction in a large artery ischemia will result to a large area of tissue • Myocardial infarction (MI) (aka heart attack) • Anastomoses do exists between smaller branches of the R and L coronary arteries

15. Blood Supply to the Heart • After traveling through the capillaries of the heart, blood empties into the R atrium via the coronary sinus

16. Conduction System of the Heart • Four structures composed of modified cardiac muscle • Sinoatrial Node (SA Node) • Pacemaker of the heart • 100s of cells in the R atrium near the opening of the superior vena cava • Atrioventricular Node (AV Node) • Small mass of cardiac muscle tissue • Left lower border of R atrium

17. Conduction System of the Heart • Atrioventricular Bundle • Also Bundle of His • Bundle of specialized cardiac muscle fibers originating in the AV node • Branches into R and L branches eventually becoming Purkinje fibers • Extend into the walls of the ventricles and papillary muscles

18. Types of Blood Vessels • Artery – carries oxygenated blood away from the heart • “distributors” • Arteriole: small artery • Precapillary sphincters: regulate the blood flow into capillaries

19. Types of Blood Vessels • Vein – carries unoxygenated blood towards the heart • Great ability to stretch (capacitance) • Function as reservoirs: blood pools in the valves then is pushed forward from the pumping pressure • Venules: small vein

20. Types of Blood Vessels

21. Types of Blood Vessels • Capillaries – arterial system switches to venous system • “primary exchange vessels” • Transport materials to and from the cells • Speed of blood flow decreases to increase contact time • Microcirculation: blood flow between arterioles, capillaries and venules

22. Types of Blood Vessels

23. Structure of Blood Vessels • Tunica adventitia - outermost layer • Fibrous connective tissue • Holds vessels open; prevents tearing of vessels walls during body movements • Larger in veins than arteries • Tunica media – middle layer • Smooth muscle and elastic CT • Helps vessels constrict and dilate • Larger in arteries

24. Structure of Blood Vessels • Tunica intima – innermost layer • Composed of endothelium • Semilunar valves present in veins • One cell thick in capillaries

25. Circulatory Routes • Systemic Circulation – blood flow from the L ventricle to the body & back to the R atrium • Pulmonary Circulation – blood flow from the R ventricle to the lungs and back to the L atrium

26. Circulatory Routes

27. Aorta

28. Arch of aorta Subclavian (L and R) Brachiocephalic common carotid (L and R) Axillary (L and R) Brachial (L and R) Radial Ulnar Abdominal aorta Common iliac External iliac Femoral Popliteal Posterior tibial Anterior tibial Dorsal pedis Systemic Arteries

30. Superior vena cava Inferior vena cava External jugular Internal jugular Brachiocephalic (L and R) Subclavian (L and R) Cephalic axillary Basilic Median basilic Median cubital Common iliac External iliac Femoral Popliteal Great saphenous Small saphenous Systemic Veins

32. Fetal Circulation • Two umbilical arteries carry blood to the placenta • The placenta allows for exchange of oxygen and nutrients from the mother. Maternal and fetal blood do NOT mix. • Umbilical vein returns oxygenated blood and enters fetus via the umbilicus • Foramen ovale – hole btwn the R and L atria • Allows for blood to bypass the R ventricle and pulmonary circulation

33. Fetal Circulation • Ductus arteriosus – small vessel connecting the pulmonary artery and the aorta • Allows for another bypass route from the lungs **Most of fetal blood is a mixture of oxygenated and deoxygenated blood**

34. Fetal Circulation

35. Changes After Birth • Umbilical vein become round ligament • Umbilical arteries become umbilical ligaments • Foramen ovale closes after first few breaths • Full closure may take up to 9 months • Ductus arteriosus contracts as soon as respirations begin • Become fibrous cord

36. Changes After Birth

37. Pericardium Disorders • Pericarditis – inflammation of the heart • Causes: trauma, viral or bacteria infection, tumor • Edema causes visceral and parietal layers to rub together = chest pain • Pus or blood build up in pericardial space • S/S • Pain with respirations or coughing, dyspnea, restlessness • Complications: Pericardial Effusion, Cardiac Tamponade • Treatment: • Antibiotics, pain meds, antiinflammatory meds, pericardiocentesis (Cardiac Tamponade)

38. Cardiac Tamponade

39. Heart Valve Disorders • General Principles: • Congenital defect: decreased pumping efficiency • Incompetent valve leak: allows backflow into previous chamber • Stenosed valves: narrowed valve; slowing blood from out of chamber

40. Heart Valve Disorders • Mitral Valve Prolapse (MVP) • Flaps of mitral valve extend back into L atrium causes leaking • Mostly genetic basis • 1 in 20 people • S/S: most asymptomatic; chest pain, fatigue • Treatment: valvuloplasty

41. Mitral Valve Prolapse

42. Heart Valve Disorders • Aortic Regurgitation • Blood leaks back into L ventricle during ejection into the aorta • Volume overload in L ventricle, hypertrophy, dilation of L ventricle • Complications: myocaridal ischemia • Treatment: valvuloplasty

43. Myocardium Disorders • Atherosclerosis • Type of arteriosclerosis • Lipids build up on the inside of vessel walls  calcify  vessels hard & brittle • Risk factors: cigarette smoking, high fat/cholesterol diet, hypertension

44. Atherosclerosis

45. Myocardium Disorders • Myocardial Infarction • “Heart Attack” • Coronary thrombosis: clot • Coronary embolism: mobilized clot • Occlude coronary artery  heart tissue deprived of oxygen  cell death • S/S: • Angina pectoris – severe chest pain resulting from inadequate oxygen to myocardium • Treatment: Coronary Bypass Surgery • Veins are harvested from other areas of the body and used to bypass obstructions

47. Myocardium Disorders • Congestive Heart Failure (CHF) • “Left-sided Heart Failure” • Inability of the L ventricle to pump blood efficiently • Causes: myocardial infarction • S/S: decreased pumping pressure in systemic circulation; retained fluids • Can lead to congestion in pulmonary circulation  pulmonary edema  right-sided heart failure • Treatment: heart transplant

48. Congestive Heart Failure

49. Myocardium Disorders • Coronary Artery Disease (CAD) • Leading cause of death in US • General term to describe decreased blood flow to myocardium & associated side effects

50. Disorders of the Arteries • Arteriosclerosis • Arteries become occluded, weak and hardened • Complications: ischemia, necrosis, gangrene • Risk factors: age, diabetes, high fat/cholesterol diet, hypertension, smoking • Treatment: vasodilators, angioplasty, stent placement, bypass surgery • Complications: aneurysm