The Cardiovascular System

Transcription

1 PowerPoint Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College The Cardiovascular System 11 PART A

2 The Cardiovascular System A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The function of the cardiovascular system is transportation - it delivers oxygen and nutrients and removes carbon dioxide and other waste products

3 The Heart Location 2/3 to the left of the midline Thorax between the lungs in the inferior mediastinum medial cavity of the thorax Orientation Pointed apex directed toward left hip where you would place a stethoscope Base points toward right shoulder About the size of your fist and weighs less than a pound

4 The Heart Figure 11.1a b

5 The Heart Figure 11.1c

6 The Heart Figure 11.2a

7 The Heart: Coverings Pericardium a double-walled sac Fibrous pericardium is loose and superficial Serous membrane is deep to the fibrous pericardium and composed of two layers Visceral pericardium Next to heart; also known as the epicardium Parietal pericardium Outside layer that lines the inner surface of the fibrous pericardium Serous fluid fills the space between the layers of pericardium

8 The Heart: Heart Wall Figure 11.2b

9 The Heart: Heart Wall Three layers Epicardium - Outside layer This layer is the visceral pericardium Connective tissue layer Myocardium - Middle layer Mostly cardiac muscle twisted and whorled into ringlike arrangement The layer that actually contracts Called the skeleton of the heart Endocardium - Inner layer Endothelium that lines heart chambers Continuous with blood vessels leaving & entering the heart

10 Homeostatic Imbalance: Pericarditis Inflammation of the pericardium Results in decrease of serous fluid Cause pericardial layers to stick together forming painful adhesions Interferes with heart movement

11 The Heart: Heart Wall Figure 11.2b

12 The Heart: Heart Wall Figure 11.2c

13 Review Questions 1 Where is the location of the heart in the thorax? What is the major function of the heart? What is the heart enclosed by? Name the two layers of the of the pericardial sac? Name the 3 layers of the heart wall What is and what causes pericarditis?

14 The Heart: Chambers Right and left side act as separate pumps Four hollow chambers 2 Atria Receiving chambers not important in pumping activity of heart 2 Ventricles Blood flows in from veins under low pressure Right atrium Left atrium Discharging chambers actual pumps of the heart Right ventricle Left ventricle

15 The Heart: Chambers Figure 11.2c

16 Differences in Right and Left Ventricles Figure 11.4

17 The Heart: Septa Septum divides the heart longitudinally Interventricular septum - Separates the two ventricles Interatrial septum - Separates the two atria

18 The Heart: Chambers Figure 11.2c

19 The Heart: Valves Allow blood to flow in only one direction to prevent backflow Four valves Atrioventricular (AV) valves between atria and ventricles Bicuspid (mitral) valve (left side of heart) Tricuspid valve (right side of heart) Anchored in place by chordae tendinae ( heart strings ) Open during heart relaxtion and closed during ventricular contrations

20 Valves Semilunar valves between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve Closed during heart relaxation but open during ventricular contraction Notice these valves operate opposite of one another to force a one-way path of blood through the heart

21 **Homeostatic Imbalance Faulty Valves heart can function with leaky valves as long as damage is not too great Incompetent valve forces heart to pump and repump same blood because valves don t close properly & blood backflows Valvular stenosis valve flaps become stiff often because of repeated endocarditis (bacterial infection of the endocardium) Forces heart to contract more vigorously increasing workload Faulty valve replaced with synthetic valve, cryopreserved human valve, or chemically treated porcine valve (pig heart valve)

22 The Heart: Valves Figure 11.2c

23 Operation of the AV valves Blood returning to the atria, puts pressure against AV valves; the AV valves are forced open Ventricles AV valves open (a) Figure 11.5a, step 1

24 Operation of the AV valves Blood returning to the atria, puts pressure against AV valves; the AV valves are forced open As the ventricles fill, AV valve flaps hang limply into ventricles Ventricles AV valves open (a) Figure 11.5a, step 2

25 Operation of the AV valves Blood returning to the atria, puts pressure against AV valves; the AV valves are forced open As the ventricles fill, AV valve flaps hang limply into ventricles Atria contract, forcing additional blood into ventricles Ventricles AV valves open (a) Figure 11.5a, step 3

26 Ventricles contract, forcing blood against AV valve flaps (a) Figure 11.5a, step 4

27 Ventricles contract, forcing blood against AV valve flaps AV valves close (a) AV valves closed Figure 11.5a, step 5

28 Ventricles contract, forcing blood against AV valve flaps AV valves close Chordae tendineae tighten, preventing valve flaps from everting into atria (a) AV valves closed Figure 11.5a, step 6

29 Operation of the semilunar valves Aorta Pulmonary trunk As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open (b) Semilunar valve open Figure 11.5b, step 1

30 Aorta Pulmonary trunk Operation of the semilunar valves As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open As ventricles relax, and intraventricular pressure falls, blood flows back from arteries, filling the leaflets of semilunar valves and forcing them to close (b) Semilunar valve open Semilunar valve closed Figure 11.5b, step 2

31 Systemic and Pulmonary Circulations Systemic circulation Blood flows from the left side of the heart through the body tissues and back to the right side of the heart Pulmonary circulation Blood flows from the right side of the heart to the lungs and back to the left side of the heart

32 Systemic and Pulmonary Circulations Figure 11.3

33 The Heart: Associated Great Vessels Arteries Aorta - Leaves left ventricle Pulmonary arteries - Leave right ventricle Veins Superior and inferior venae cavae - Enter right atrium Pulmonary veins (four) - Enter left atrium

34 The Heart: Associated Great Vessels Figure 11.2c

35 Blood Flow Through the Heart Superior and inferior venae cavae dump blood into the right atrium From right atrium, through the tricuspid valve, blood travels to the right ventricle From the right ventricle, blood leaves the heart as it passes through the pulmonary semilunar valve into the pulmonary trunk Pulmonary trunk splits into right and left pulmonary arteries that carry blood to the lungs

36 Blood Flow Through the Heart Oxygen is picked up and carbon dioxide is dropped off by blood in the lungs Oxygen-rich blood returns to the heart through the four pulmonary veins Blood enters the left atrium and travels through the bicuspid valve into the left ventricle From the left ventricle, blood leaves the heart via the aortic semilunar valve and aorta

37 Systemic and Pulmonary Circulations Figure 11.3

38 Coronary Circulation Blood in the heart chambers does not nourish the myocardium The heart has its own nourishing circulatory system consisting of Coronary arteries branch from the aorta to supply the heart muscle with oxygenated blood Cardiac veins drain the myocardium of blood Coronary sinus a large vein on the posterior of the heart, receives blood from cardiac veins Blood empties into the right atrium via the coronary sinus

39 ** Homeostatic Imbalance Angina Pectoris crushing chest pain caused by oxygen deprivation of the myocardium Infarct caused by prolonged oxygen deprivation where heart cells die Myocardial infarction heart attack or coronary

40 The Heart: Associated Great Vessels Figure 11.2c

41

42 Review Questions 3 1. Compare and contrast systemic versus pulmonary circulation. 2. Which side of the heart carries oxygenated blood? Deoxygenated blood? 3. What is the major artery leaving the heart? The major veins returning blood to the heart? 4. Where do the pulmonary vessels travel to & from? 5. In linear fashion list flow of blood with arrows? 6. How does the cardiac muscle tissue receive nourishment? 7. Compare and contrast angina pectoris with an infarct.

43 II. Physiology of the Heart Intrinsic conduction system (nodal system) Heart muscle cells contract, without nerve impulses, in a regular, continuous way

44 The Heart: Conduction System Special tissue sets the pace similar to cross between muscle & nervous tissue Sinoatrial node = SA node ( pacemaker ), is in the right atrium Atrioventricular node = AV node, is at the junction of the atria and ventricles Atrioventricular bundle = AV bundle (bundle of His), is in the interventricular septum Bundle branches are in the interventricular septum Purkinje fibers spread within the ventricle wall muscles

45 Heart Contractions Figure 11.6

46 Heart Contractions Contraction is initiated by the sinoatrial node (SA node) Sequential stimulation occurs at other autorhythmic cells Force cardiac muscle depolarization in one direction from atria to ventricles

47 Heart Contractions Once SA node starts the heartbeat Impulse spreads to the AV node Then the atria contract At the AV node, the impulse passes through the AV bundle, bundle branches, and Purkinje fibers Blood is ejected from the ventricles to the aorta and pulmonary trunk as the ventricles contract

48 Heart Contractions Figure 11.6

49 Heart Contractions Tachycardia rapid heart rate over 100 beats per minute Bradycardia slow heart rate less than 60 beats per minutes

50 **Homeostatic Imbalance Heart block when the AV node is damaged allowing the ventricles to beat at their own slower rate Ischemia lack of adequate blood supply which leads to fibrillation- rapid uncoordinated shudddering of heart muscles Pacemaker will need to be inserted to correct this condition.

51 The Heart: Cardiac Cycle In a healthy heart, atria contract simultaneously Atria relax, then ventricles contract Systole = contraction Diastole = relaxation

52 Filling Heart Chambers: Cardiac Cycle Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Atrial contraction Isovolumetric Ventricular contraction phase ejection phase Isovolumetric relaxation Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Early diastole Figure 11.7

53 Filling Heart Chambers: Cardiac Cycle Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Mid-to-late diastole (ventricular filling) Figure 11.7, step 1a

54 Filling Heart Chambers: Cardiac Cycle Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Atrial contraction Mid-to-late diastole (ventricular filling) Figure 11.7, step 1b

55 Filling Heart Chambers: Cardiac Cycle Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Atrial contraction Isovolumetric contraction phase Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Figure 11.7, step 2a

56 Filling Heart Chambers: Cardiac Cycle Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Atrial contraction Isovolumetric Ventricular contraction phase ejection phase Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Figure 11.7, step 2b

57 Filling Heart Chambers: Cardiac Cycle Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Atrial contraction Isovolumetric Ventricular contraction phase ejection phase Isovolumetric relaxation Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Early diastole Figure 11.7, step 3

58 The Heart: Cardiac Cycle Cardiac cycle events of one complete heart beat Mid-to-late diastole blood flows from atria into ventricles Ventricular systole blood pressure builds before ventricle contracts, pushing out blood Early diastole atria finish refilling, ventricular pressure is low

59 Heart Sounds When using a stethoscope you hear two distinct sounds in a cardiac cycle. These heart sounds are described by two syllables lub and dup The lub is caused by the closing of the AV valves (bicuspid and tricuspid) The dup occurs when the semilunar valves close.

60 ** Homeostatic Imbalance - Murmurs Murmur abnormal or unusual heart sounds Fairly common in young children (and some elderly people) with perfectly healthy hearts probably due to thin heart walls. Outside of these groups a murmur may indicate a valve problem.

61 The Heart: Regulation of Heart Rate Increased heart rate Sympathetic nervous system Crisis stressors (physical or emotional trauma, high body temp.) Low blood pressure Hormones can also increase heart rate Epinephrine Thyroxine Exercise working muscles generate heat which increases heart rate by boosting metabolism

62 The Heart: Regulation of Heart Rate Decreased heart rate Parasympathetic nervous system slow and steady the heart giving it time to rest.

63 Cardiac Output Regulation Figure 11.8

64 ** Homeostatic Imbalance Congestive heart failure when the pumping efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs. A progressive condition that may be caused by coronary atherosclerosis (blockage of coronary vessels with fatty buildup), persistent high blood pressure or multiple myocardial infarctions

65 Congestive Heart Failure (CHF) Each side can fail independently If the left side fails it is pulmonary congestion because the right side continues to send blood to the lungs but the left side can not discharge blood into systemic circuclation Lungs become swollen with blood, pressure increases and fluid leaks into lung tissue causing pulmonary edema If untreated the patient suffocates

66 Congestive Heart Failure (CHF) If the right side fails peripheral congestion occurs as blood backs up in the systemic circulation Edema is most noticeable in distal parts of the body; feet, ankles, and fingers become swollen and puffy Failure of one side puts a greater strain on the other side and eventually the whole heart fails

67 Heart Pop Quiz Word Bank Superior vena cava Inferior vena cava Right atrium Bicuspid valve Right ventricle Aortic Semilunar valve Right Pulmonary artery Left Pulmonary artery Right pulmonary vein Left pulmonary vein Left atrium Tricuspid valve Left ventricle Aorta Septum Pulmonary semilunar valve Pulmonary trunk