1. 1 Chapter 15 Cardiovascular System

2. 2 Size of Heart Average Size of Heart 14 cm long 9 cm wide 250-350 grams About size of your closed fist

3. 3 Location of Heart Posterior to sternum Medial to lungs Anterior to vertebral column Base lies beneath 2 nd rib Apex at 5 th intercostal space Lies upon diaphragm 2/3 of mass lies left of midline

4. 4 Coverings of Heart

5. 5 Pericardium –Surrounds heart –Fibrous pericardium Resembles bag that sits on the diaphragm Provides tough protection & anchors heart to mediastinum Coverings of Heart

6. 6 Pericardium –Serous pericardium Thinner & delicate Parietal layer –Attached to fibrous pericardium Visceral layer –Attached to myocardium Coverings of Heart

7. 7 Pericardial Fluid –Between parietal and visceral layers of serous pericardium –Reduces friction from beating Coverings of Heart

8. 8 Wall of the Heart

9. 9 3 Parts of the wall Epicardium Visceral layer of serous pericardium Myocardium Muscle layer Endocardium Thin layer of endothelial tissue that is continuous with the remainder of the cardiovascular system

10. 10 Heart Chambers Right Atrium Receives blood from Inferior vena cava Superior vena cava Coronary sinus Right Ventricle Receives blood from right atrium

11. 11 Left Atrium receives blood from pulmonary veins Left Ventricle receives blood from left atrium Heart Chambers

12. 12 Separations –Atria Each atrium has an auricle Separated by interatrial septum –Ventricles Interventricular septum Sulci show the location of septum –Contain blood vessels and store fat Heart Chambers

13. 13 Heart Valves Atrioventricular Valves Separate atria from ventricles Tricuspid Valve Right side 3 cusps Bicuspid valve Left side 2 cusps Chordae Tendineae Fibrous cord that connects cusps to papillary muscles

14. 14 Atrioventricular Valves –Papillary Muscles Anchor chordae tendineae to ventricle walls –Chordae Tendineae & Papillary Muscles Function to keep AV valves from being pushed into the atria during ventricular contraction Heart Valves

15. 15 Semilunar Valves –Pulmonary semilunar Between right ventricle and pulmonary trunk Blood leaves heart toward lungs –Aortic semilunar Between left ventricle and aorta Blood leaves heart toward body –Prevent backflow to keep blood flowing in one direction Heart Valves

16. 16 Coronal Sections of Heart

17. 17 Heart Valves Tricuspid ValvePulmonary and Aortic Valve

18. 18 Path of Blood Through the Heart

19. 19 Superior/Inferior Vena Cava/Coronary Sinus bring blood to right atrium Blood flows through tricuspid valve to right ventricle Right ventricle pumps blood through pulmonary semilunar valve to pulmonary trunk/pulmonary arteries Path of Blood Through the Heart

20. 20 Pulmonary arteries take blood to lungs Blood returns to heart through pulmonary veins to left atrium Blood flows through bicuspid valve to left ventricle Blood leaves left ventricle through aortic semilunar valve to ascending aorta Aorta takes blood to body Blood returns to heart through veins leading to inferior vena cava & superior vena cava Path of Blood Through the Heart

21. 21 Path of Blood Through the Heart

22. 22 Blood Supply to Heart

23. 23 Left & right coronary arteries originate from the ascending aorta –Carry oxygenated blood to myocardium Coronary Sinus carries deoxygenated blood to right atrium Anastomosis –2 different arteries connecting & supplying an area with blood flow –Found throughout body, many in heart –Provides collateral circulation for blood to reach an organ Blood Supply to Heart

24. 24 Blood Supply to Heart

25. 25 Blood Supply to Heart

26. 26 Angiogram of Coronary Arteries

27. 27 Heart Actions Systole Phase of contraction Diastole Phase of relaxation Cardiac Cycle One complete heart beat Consists of systole & diastole of both atria Systole & diastole of both ventricles

28. 28 Cardiac Cycle Atrial Systole/Ventricular Diastole blood flows passively into ventricles remaining 30% of blood pushed into ventricles A-V valves open/semilunar valves close ventricles relaxed ventricular pressure increases

29. 29 Cardiac Cycle Ventricular Systole/Atrial diastole A-V valves close chordae tendinae prevent cusps of valves from bulging too far into atria atria relaxed blood flows into atria ventricular pressure increases & opens semilunar valves blood flows into pulmonary trunk & aorta

30. 30 Heart Sounds Lubb first heart sound occurs during ventricular systole A-V valves closing Dupp second heart sound occurs during ventricular diastole pulmonary and aortic semilunar valves closing

31. 31 Clinical Application Murmur – any condition that causes unusual sounds to heard before or after the lubb-dupp Noises caused by turbulent blood flow Mitral and Aortic Stenosis –Narrowing of either valve by scar formation or congenital defect Mitral and Aortic insufficiencies –Backflow of blood because the cusp doesn’t close properly Heart Sounds

32. 32 Clinical Application Mitral Valve Prolapse –Inherited disorder in which the mitral valve is pushed back too far during contraction –Usually asymptomatic –About 10% of population has this disorder Heart Sounds

33. 33 Heart Sounds

34. 34 Cardiac Conduction System

35. 35 4 main parts –Sinoatrial node (SA node) “pacemaker” Found in right atrial wall inferior to the opening of the vena cava –Atrioventricular node (AV node) Found near inferior portion of the interatrial septum –Impulse from SA node travels across atria (stimulates atrial contraction) then stimulates AV node Cardiac Conduction System

36. 36 AV bundle –Conducting fibers run from the AV node to top of interventricular septum and branches into two –Distributes potential over medial surface of the ventricles Purkinje Fibers (conduction myofibers) –Pass from bundle branches into the myocardium –Stimulates the contraction of the ventricles Cardiac Conduction System

37. 37 Cardiac Conduction System

38. 38 Muscle Fibers in Ventricular Walls

39. 39 Electrocardiogram Recording of electrical changes that occur in the myocardium Used to assess heart’s ability to conduct impulses

40. 40 P wave Atrial depolarization Fraction of a second after atria contract Electrocardiogram

41. 41 QRS wave Ventricular depolarization Downward deflection (Q) Large upward peak (R) Ventricular depolarization Fraction of a second after the completion of this wave, ventricles may contract again Electrocardiogram

42. 42 T wave – ventricular repolarization Electrocardiogram

43. 43 Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers

44. 44 Regulation of Cardiac Cycle Autonomic nerve impulses alter the activities of the S-A and A-V nodes

45. 45 Regulation of Cardiac Cycle physical exercise body temperature concentration of various ions potassium calcium parasympathetic impulses decrease heart action sympathetic impulses increase heart action cardiac center regulates autonomic impulses to the heart Additional Factors that Influence HR

46. 46 Blood Vessels Arteries Carry blood away from ventricles of heart Arterioles Receive blood from arteries Carry blood to capillaries Capillaries Sites of exchange of substances between blood and body cells Venules Receive blood from capillaries Veins Carry blood toward atria of heart Vasa Vasorum Blood vessels in vascular tissue walls Nourish vascular tissue

47. 47 Arteries and Arterioles Artery thick strong wall endothelial lining middle layer of smooth muscle and elastic tissue outer layer of connective tissue carries blood under relatively high pressure Arterioles thinner wall than artery endothelial lining some smooth muscle tissue small amount of connective tissue helps control blood flow into a capillary

48. 48 Walls of Artery and Vein

49. 49 Composed of 3 layers (tunics) –Tunica Interna Inner wall (tunic)/ Endothelium Simple squamous epithelium Layer of elastic tissue (internal elastic lamina) Extremely thin in veins Walls of Artery and Vein

50. 50 –Tunica media Middle tunic Thickest smooth muscle Elastic fibers Thinner in veins Walls of Artery and Vein

51. 51 –Tunica Externa Outer tunic Composed of elastic and collagenous fibers Thicker in veins Walls of Artery and Vein

52. 52 Walls of Artery and Vein

53. 53 Walls of Artery and Vein

54. 54 Elastic conducting arteries –Conduct blood from the heart to the medium sized arteries –Large diameter with relatively thin walls Tunica media has more elastic fibers and less smooth muscle –Must be able to withstand high blood pressures –Aorta, Common carotid Types of Arteries

55. 55 Muscular Distributing Arteries –Distribute blood to the rest of the body –More smooth muscle in tunica media –Regulate blood needs of structures they serve –Anastomoses likely to occur in this type of artery –Axillary, brachial, femoral, popliteal Types of Arteries

56. 56 Arterioles –Smallest arterioles only have a few smooth muscle fibers –Capillaries lack muscle fibers –Deliver & regulate blood to capillaries Types of Arteries

57. 57 Metarteriole Connects arteriole directly to venule

58. 58 Capillaries Smallest diameter blood vessels Only one RBC at a time Extensions of inner lining of arterioles Walls are endothelium only Only 1 cell layer thick Semi-permeable Found near almost every cell in the body The higher the tissue’s activity, the more capillaries present Sinusoids – leaky capillaries

59. 59 Capillaries

60. 60 Capillary Network

61. 61 Regulation of Capillary Blood Flow Precapillary sphincters may close a capillary respond to needs of the cells low oxygen and nutrients cause sphincter to relax

62. 62 Exchange in the Capillaries Water and other substances leave capillaries because of net outward pressure at the capillaries’ arteriolar ends Water enters capillaries’ venular ends because of a net inward pressure Substances move in and out along the length of the capillaries according to their respective concentration gradients

63. 63 Exchange in the Capillaries

64. 64 Venules and Veins Venule thinner wall than arteriole less smooth muscle and elastic tissue than arteriole collects blood from capillaries & drain into the veins Vein thinner wall than artery three layers to wall but middle layer is poorly developed some have flaplike valves carries blood under relatively low pressure serves as blood reservoir

65. 65 Venous Valves

66. 66 Disorders –Varicose Veins Valves are weak allowing gravity to force large quantities of blood into distal parts of the veins Pressure stretches vein and causes it to lose elasticity Veins become stretched and flabby Deep veins are not susceptible Venous Valves

67. 67 Blood Volumes in Vessels

68. 68 Arterial Blood Pressure Blood Pressure – force the blood exerts against the inner walls of the blood vessels Arterial Blood Pressure rises when ventricles contract falls when ventricles relax systolic pressure – maximum pressure diastolic pressure – minimum pressure

69. 69 Blood Pressure (BP) –Pressure on arterial wall due to the left ventricle contraction –Blood flows from high to low pressures –Average aorta pressure is 100mmHg –Average right atrium pressure is nearly 0 mmHg –Normal resting BP is 120 mmHg (systolic) 80 mmHg (diastolic) –Measured with a sphygomanometer Blood Flow Factors

70. 70 Blood Flow Factors

71. 71 Resistance –Friction as blood travels –Related to Viscosity –Ratio of RBC and solutes to liquid –Anything that decreases viscosity (dehydration) increases BP Blood Vessel Length –Longer vessel = higher resistance Blood Vessel Radius –Resistance inversely proportional to the 4th power, the radius of the vessel Blood Flow Factors

72. 72 Pulse alternate expanding and recoiling of the arterial wall that can be felt

73. 73 Factors That Influence Arterial Blood Pressure

74. 74 Cardiac Output –Amount of blood ejected by the left ventricle into the aorta each minute –Main factor of BP Blood Volume –Average is about 5 liters –Decreased volume = decreased pressure –Increased volume = increased pressure High salt intake  retain water  increased blood volume Factors That Influence Arterial Blood Pressure

75. 75 Peripheral Resistance –All of the vascular resistance offered by the cardiovascular system –Major function of arterioles is to control resistance Capillary Exchange –Blood flow is at its slowest to aid in exchange of gases and nutrients –Depends on concentration differences Factors That Influence Arterial Blood Pressure

76. 76 Control of Blood Pressure Controlling cardiac output and peripheral resistance regulates blood pressure

77. 77 Venous Blood Flow Not a direct result of heart action Dependent on Skeletal muscle contraction Breathing Venoconstriction

78. 78 Velocity of blood flow Skeletal muscles and valves in veins –Venous milking Muscle contracts and “squishes” blood upward Valves keep blood from flowing backward with gravity Breathing –Decreases pressure in thoracic cavity and increases pressure in abdominal cavity Venous Blood Flow Factors

79. 79 Central Venous Pressure pressure in the right atrium factors that influence it alter flow of blood into the right atrium affects pressure within the peripheral veins weakly beating heart increases central venous pressure increase in central venous pressure causes blood to back up into peripheral vein

80. 80 Pulmonary Circuit consists of vessels that carry blood from right ventricle of the heart to the lungs and back to the left atrium of the heart

81. 81 Blood Flow Through Alveoli cells of alveolar wall are tightly joined together the high osmotic pressure of the interstitial fluid draws water out of them

82. 82 Systemic Circuit Composed of vessels that lead from the heart to all body parts (except the lungs) and back to the heart Includes the aorta and its branches Includes the system of veins that return blood to the right atrium

83. 83 Coronary –Circulation through blood vessels supplying the heart Hepatic Portal –Runs from GI tract to the liver Additional Circuits

84. 84 Time required for blood to travel from the right atrium through pulmonary circulation and systemic circulation and back to the right atrium Average is about 1 minute Circulation Time

85. 85 Alternating expansion and recoil of an arterial wall Stronger closer to the heart Measured by counting for 15 seconds and multiplying by 4 Most commonly used artery is the radial artery Pulse

86. 86 Other commonly used arteries –Temporal –Facial –Common carotid  lateral to the larynx –Brachial artery  medial sides of biceps brachii –Femoral –Popliteal  behind the knee –Posterial Tibial  posterior to medial malleolus –Dorsalis Pedis  superior to the longitudinal arch of the foot Pulse

87. 87 Life-Span Changes cholesterol deposition in blood vessels heart enlargement death of cardiac muscle cells increase in fibrous connective tissue of the heart increase in adipose tissue of the heart increase in blood pressure decrease in resting heart rate

88. 88 Clinical Application Arrhythmias Ventricular fibrillation rapid, uncoordinated depolarization of ventricles Tachycardia rapid heartbeat Atrial flutter rapid rate of atrial depolarization

89. 89 Angina Pectoris –Chest pain –Reduced oxygen supply weakens cardiac cells but doesn’t kill them –Symptoms Tightness of choking sensation Squeezing pressure type of sensation for short durations –Causes Stress, exertion, hypertension Clinical Application

90. 90 Myocardial Infarction (MI) –Heart attack –Infarction means death of tissue due to lack of blood supply –Myocardial tissue behind blocked arteries dies –Dead tissue may disturb conducting system of the heart which could lead to sudden death (ventricular fibrillation) Clinical Application

91. 91 Shock –Failure of cardiovascular system to deliver adequate amounts of oxygen and nutrients to meet the metabolic needs of body cells because of inadequate cardiac output Clinical Application

92. 92 Shock Signs and Symptoms –Systolic PB lower than 90 mmHg as a result of vasodilation and decreased cardiac output –Clammy, cool, pale skin due to vasoconstriction of blood vessels in the skin –Sweating due to increased levels of epinephrine –Rapid heart rate Clinical Application

93. 93 Signs and Symptoms –Lactic acid build-up –Weak pulse –Altered mental state –Thirst due to extra-cellular fluid loss Clinical Application