1. Heart Structure

2. Heart – located in mediastinum within the thoracic cavity

3. The Pericardium – membrane surrounding heart

4. Serous Pericardium = 1. Parietal - outer layer 2. Visceral - inner layer (part of epicardium)

5. Layers of Heart Wall Epicardium – outermost layer – synonymous with visceral portion of serous membrane Myocardium – middle layer – Cardiac muscle – Pumping chamber Endocardium – innermost layer – Smooth surface to reduce friction

6. Layers of Heart Wall

8. Chambers of Heart

9. Heart Chambers and Valves

10. Heart Valves

11. AV Valves - structure

13. Heart Chambers, Valves and Vessels

14. Heart Chambers, Valves, and Vessels

15. Pulmonary vs Systemic Circulation

17. Coronary Circulation

18. Homeostatic Imbalance: Mycardial Infarctions

20. Intrinsic Conduction System of the Heart

22. Intrinsic Conduction System Also called nodal system Sinoatrial (SA) Node = pacemaker  Atria  Atria Contract  Atrioventricular (AV) Node  Brief Delay  Atrioventricular bundle (bundle of His)  Bundle branches  Purkinje fibers  Contraction of ventricle from bottom up  Blood pushed out of ventricles

23. Homeostatic Imbalances Heart block = Damage to AV node which allows ventricles to pump at own rate, which is typically slower than normal Fibrillation = rapid uncoordinated shuddering of heart muscle, makes heart useless, major cause of death from heart attacks Tachycardia = rapid heart rate +100bpm Bradycardia = slow heart rate < 60bpm

24. Cardiac Cycle =.8 seconds Sequence of Events in one heartbeat – Contraction of both atria – Contraction of both ventricles Systole = contraction – of ventricle Diastole = relaxation – of ventricle Lub = closing of AV valves Dub = closing of semilunar valves

25. Cardiac Cycle Systole: – Ventricles contract – AV Close = “Lub” – Semi-lunar open Diastole: – Ventricle relax – AV valve open – Semi-lunar closed= “Dub”

26. Cardiac Cycle

30. Cardiac Output Cardiac Output = amount of blood pumped out by EACH side of the heart in 1 minute CO = HR X SV HR = heart rate or beats per minute SV = stroke volume = amount of blood pumped out be each ventricle with each heartbeat If either HR or SV varies, the other tries to compensate to keep the cardiac output stable

32. Factors Affecting Heartrate Autonomic NS – most important external influence on heart – Sympathetic – increase heart rate – Parasympathetic – slow and steady heartrate (vagus nerve) Hormones – Epinephrine and thyroxine – increase heartrate Physical factors – Age, gender, exercise, body temperature

33. Factors Affecting Stroke Volume How much cardiac muscle stretched before contraction More stretch = more contraction Venous return determines amount of stretch Greater venous return = Greater SV Increase SV – Slow Heartrate – Exercise Decrease SV – Severe blood loss – Very Rapid heartrate

35. Regulation of Heart Rate = most important external influence on heart rate

36. Homeostatic Imbalance: Congestive Heart Failure When the pumping efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs Usually progressive condition that reflects weakening of the heart by atherosclerosis, persistent high blood pressure, or multiple myocardial infarctions

37. Congestive Heart Failure Pulmonary Congestions Left side failure Right side pumps to lungs Left side cannot pump to body Blood pressure inside lungs increases and fluid leaks into lung tissue Pulmonary edema Person can suffocate Peripheral Congestion Right side failure Blood backs up in systemic circulation Edema in most distal parts of body

39. Review Questions – True of False The ventricles contract in diastole The AV valves are open during systole The SA node is the pacemaker of the heart Increased venous return will decrease stroke volume Parasympathetic NS keeps heartrate slow and steady

40. ECG or EKG – electrical activity of the heart – depolarize–contract – repolarize–relax Electrocardiogram

41. Electrocardiogram = ECG P wave – Depolarization of atria – Atria contract QRS complex – Depolarization of ventricles – Repolarization of atria – Ventricles contract (atria relax) T wave – Repolarization of ventricles – Ventricles relax

42. Normal ECG

43. bradycardia – slow heart beat tachycardia – fast heart beat premature atrial contraction (PACs) – atria contracts before SA node Cardiac Arrhythmias

44. atrial fibrillation – atria contract faster than 350 bpm premature ventricular contractions (PVCs) – ventricles contract too soon ventricular tachycardia (VT) – ventricles, rather than SA node, cause beat Cardiac Arrhythmias

45. ventricular fibrillation (VF) – ventricles contract faster than 350 bpm heart block – impulse from SA node to AV node first–impulse delayed second–intermittently blocked third–completely blocked Cardiac Arrhythmias

46. blood vessels: the transport network circulation: moving blood around the body taking vital signs know your numbers Closed system – blood always in a vessel or heart Blood Vessels and Circulation

47. tunica intima – innermost layer – Epithelial tissue tunica media – middle layer – Smooth muscle tunica externa – outermost layer – Connective tissue The Three Layers of Blood Vessels

50. Blood Pathway Heart  Arteries  Arterioles  Capillaries  Venules  Veins  Heart

51. Arteries Carry blood AWAY from heart Blood usually oxygenated – exception is pulmonary artery Thick walls, narrow lumen Walls elastic – expand and contract with pulse Arterioles – smaller arteries – Dilate and constrict to alter blood flow – Ex. Muscles dilate when running Two organs blood supply never changes = brain and kidneys

52. Capillaries Smallest of all blood vessels Only one cell thick Narrow – blood cells flow single file Very large surface area for gas, nutrient, and waste exchange Blood moves slower through here to allow time for exchanges

53. Veins Carries deoxygenated back to the heart – Exception: Pulmonary vein Thinner and less elastic, more flexible Larger veins contain valves – Prevent backflow Skeletal muscles and breathing help return blood to heart When inhale, drop in pressure occurs in thorax causing large veins near heart to expand and fill

55. structure and function of vessels Blood Vessels: The Transport Network

56. Factors Influencing Venous Return Lumen of veins larger than arteries Large veins have valves that prevent backflow Skeletal muscles help “milk” blood through veins towards heart When inhale, drop in pressure occurs in thorax causing large veins near heart to expand and fill

57. Anatomy of Capillary Bed Two types of vessels A. vascular shunt – vessel that directly connect the arteriole and venule at opposite ends of the bed B. true capillaries – actual exchange vessels – 10 – 100 per capillary bed – Precapillary sphincter surrounds each to act as cut-off valve and regulate blood flow

60. Capillary Exchange Substances tend to move into and out of body cells according to their concentration gradients. Oxygen and nutrients: blood  tissue cells CO 2 and waster: tissue cells  blood

61. How Solutes Move In and Out 1. Diffusion – lipid soluble 2. Endocytosis and Exocytosis – lipid insoluble 3. Intercellular clefts – special diffusion through gaps between cell membranes of adjoining cells 4. Fenestrated capillaries – special capillaries filled with pores. Found in areas where absorption and filtration important

62. Fluid Movement - due to differences in pressure Blood pressure highest - arterial end – Fluid moves out of capillaries Osmotic pressure highest - venule end – Fluid moves into capillaries

63. Homeostatic Imbalance – Varicose Veins

64. Thrombophlebitis Complication of varicose veins Inflammation of a vein that results when a clot forms in vein with poor circulation Common Consequence: clot detachment and pulmonary embolism

65. Special Circulations Arterial Supply of Brain and Circle of Willis – – Supplied by 2 sets of arteries – These blood supplies are united by special arteries – Result is complete circle of connecting blood vessels called the circle of Willis – Protects the brain because it provides more than one route for blood to reach the brain

66. Special Circulations Hepatic Portal Circulation – Veins drain the digestive organs and deliver blood to liver – Liver processes nutrients before make it to systemic circulation Fetal Circulation – All nutrient, excretory, and gas exchange occur through placenta – Umbilical veins and arteries