1. Copyright © 2010 Pearson Education, Inc. Cardiovascular System components The heart Blood vessels Blood

2. Copyright © 2010 Pearson Education, Inc.

3. Heart Anatomy Approximately the size of a fist Location In the mediastinum between second rib and fifth intercostal space On the superior surface of diaphragm Two-thirds to the left of the midsternal line Anterior to the vertebral column, posterior to the sternum Enclosed in pericardium, a double-walled sac

4. Copyright © 2010 Pearson Education, Inc. Coverings of the Heart: Anatomy The heart is enclosed in a double-walled sac called the pericardium. Superficial fibrous pericardium Protects, anchors, and prevents overfilling The outer parietal pericardium consists of a tough fibrous layer of dense connective tissue. The inner thin, smooth, moist serous layer turns in at the base of the heart, forming the visceral pericardium/epicardium covering the heart surface. Between the parietal and visceral pericardia is a space called the pericardial cavity. It contains pericardial fluid that lubricates the membranes and allows the heart to beat almost without friction.

5. Copyright © 2010 Pearson Education, Inc. Layers of the Heart Wall myocardium Spiral bundles of cardiac muscle cells to allow “twisting” when contracting Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue Supply structural support for the heart Anchors cardiocytes and give them something to pull against Limits spread of action potentials to specific paths

6. Copyright © 2010 Pearson Education, Inc. Heart Chambers Atrium – single Atria - pleural Ventricle/s http://mtsu32.mtsu.edu:11259/heart3.jpg

7. Copyright © 2010 Pearson Education, Inc. Atria of the Heart Atria are the receiving chambers of the heart – entering veins Blood enters right atria from superior and inferior venae cavae and coronary sinus Blood enters left atria from pulmonary veins Each atrium has a auricle that increase atrial volume Separated internally by the interatrial septum Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles Pectinate muscles mark the anterior atrial wall

8. Copyright © 2010 Pearson Education, Inc. Ventricles of the Heart Ventricles are the discharging chambers of the heart Right ventricle pumps blood into the pulmonary trunk Left ventricle pumps blood into the aorta Papillary muscles that attached to the valves

9. Copyright © 2010 Pearson Education, Inc. Figure 18.4e

10. Copyright © 2010 Pearson Education, Inc. Heart Valves Heart valves ensure unidirectional blood flow through the heart (prevent backflow) Atrioventricular (AV) valves lie between the atria and the ventricles AV valves prevent backflow into the atria when ventricles contract Chordae tendineae anchor AV valves to papillary muscles Semilunar valves prevent backflow of blood into the ventricles Aortic semilunar valve lies between the left ventricle and the aorta Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk

11. Copyright © 2010 Pearson Education, Inc. 1.mitral (bicuspid) 2.tricuspid 3.Pulmonary semilunar 4.aortic semilunar http://mtsu32.mtsu.edu:11259/heart.htm

12. Copyright © 2010 Pearson Education, Inc. Figure 20-8a Valves of the Heart Aortic valve (closed) LEFT ATRIUM Left AV (bicuspid) valve (open) Chordae tendineae (loose) Papillary muscles (relaxed) LEFT VENTRICLE (relaxed and filling with blood) Pulmonary veins Frontal Sections through Left Atrium and Ventricle Relaxed ventricles

13. Copyright © 2010 Pearson Education, Inc. Figure 20-8b Valves of the Heart Contracting ventricles Aortic valve open RIGHT VENTRICLE Right AV (tricuspid) valve (closed) Cardiac skeleton Left AV (bicuspid) valve (closed) LEFT VENTRICLE Aortic valve (open) Pulmonary valve (open) When the ventricles are contracting, the AV valves are closed and the semilunar valves are open. In the frontal section notice the attachment of the left AV valve to the chordae tendineae and papillary muscles.

14. Copyright © 2010 Pearson Education, Inc. Figure 20-8b Valves of the Heart Contracting ventricles Aorta Aortic sinus LEFT ATRIUM Aortic valve (open) Left AV (bicuspid) valve (closed) Chordae tendineae (tense) Papillary muscles (contracted) Left ventricle (contracted)

15. Copyright © 2010 Pearson Education, Inc. Figure 18.9 1 Blood returning to the heart fills atria, putting pressure against atrioventricular valves; atrioventricular valves are forced open. 1 Ventricles contract, forcing blood against atrioventricular valve cusps. 2 As ventricles fill, atrioventricular valve flaps hang limply into ventricles. 2 Atrioventricular valves close. 3 Atria contract, forcing additional blood into ventricles. 3 Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria. (a) AV valves open; atrial pressure greater than ventricular pressure (b) AV valves closed; atrial pressure less than ventricular pressure Direction of blood flow Atrium Ventricle Cusp of atrioventricular valve (open) Chordae tendineae Papillary muscle Atrium Blood in ventricle Cusps of atrioventricular valve (closed)

16. Copyright © 2010 Pearson Education, Inc. Figure 18.10 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 cusps of semilunar valves and forcing them to close. (a) Semilunar valves open (b) Semilunar valves closed Aorta Pulmonary trunk

17. Copyright © 2010 Pearson Education, Inc. Heart Sounds Two sounds (lub-dup) associated with closing of heart valves First sound occurs as AV valves close and signifies beginning of systole Second sound occurs when SL valves close at the beginning of ventricular diastole Heart murmurs: abnormal heart sounds most often indicative of valve problems

18. Copyright © 2010 Pearson Education, Inc. Heart valves problems Valvular heart disease (VHD) When valve function has deteriorated to where heart cannot maintain adequate blood flow Can be due to: Congenital (present at birth) malformations Heart swelling (carditis) In severe cases, replacement with a prosthetic valve may be necessary Bioprosthetic valves come from pigs or cows

19. Copyright © 2010 Pearson Education, Inc. Vessels that Supply/Drain the Heart - coronary circulation Figure 18.7

20. Copyright © 2010 Pearson Education, Inc. Risk factors that can lead to heart diseases Coronary artery disease High blood pressure Diabetes Smoking High cholesterol Obesity Excessive alcohol use Drug abuse Stress Family history of heart disease Advancing age

21. Copyright © 2010 Pearson Education, Inc. Arteriosclerosis and coronary artery disease Arteriosclerosis (arterio-, artery + sclerosis, hardness) Thickening or toughening of artery walls Related complications account for about half of all U.S. deaths

22. Copyright © 2010 Pearson Education, Inc. Arteriosclerosis and coronary artery disease Atherosclerosis (athero-, fatty degeneration) Formation of lipid deposits Most common form of arteriosclerosis Often associated with elevated cholesterol May form fatty tissue mass (plaque) in vessel that restricts blood flow Most common in older men Treatment can be removing damaged vessel or compressing plaque with balloon angioplasty

23. Copyright © 2010 Pearson Education, Inc. Heart Disease - Coronary Artery Disease (CAD) Areas of partial or complete blockage of coronary circulation Reduction in blood flow to heart muscle produces a corresponding reduction in cardiac performance Reduced circulatory supply causes coronary ischemia One of the first symptoms of CAD is commonly angina pectoris – pain in the middle of the chest, left neck, left shoulder, or left arm

24. Copyright © 2010 Pearson Education, Inc. Myocardial infarction (MI), or heart attack Part of the coronary circulation becomes blocked, and cardiac muscle cells die from lack of oxygen The death of affected tissue creates a nonfunctional area known as an infarct Heart attacks most commonly result from severe coronary artery disease (CAD)

25. Copyright © 2010 Pearson Education, Inc. Myocardial infarction (MI), or heart attack Consequences depend on the site and nature of the circulatory blockage If it occurs near the start of one of the coronary arteries: The damage will be widespread and the heart may stop beating If the blockage involves one of the smaller arterial branches: The individual may survive the immediate crisis but may have many complications such as reduced contractility and cardiac arrhythmias

26. Copyright © 2010 Pearson Education, Inc. Myocardial infarction (MI), or heart attack Pain does not always accompany a heart attack therefore, the condition may go undiagnosed and may not be treated before a fatal MI occurs A myocardial infarction can usually be diagnosed with an ECG and blood studies Damaged myocardial cells release enzymes into the circulation, and these elevated enzymes can be measured in diagnostic blood tests The enzymes include: Cardiac troponin T, Cardiac troponin I, A special form of creatinine phosphokinase, CK-MB

27. Copyright © 2010 Pearson Education, Inc. CAD and Myocardial Infarction prognosis About 25% of MI patients die before obtaining medical assistance 65% of MI deaths among those under age 50 occur within an hour after the initial infarction

28. Copyright © 2010 Pearson Education, Inc. Treatment of CAD and Myocardial Infarction Risk Factor Modification Stop smoking High blood pressure treatment Dietary modification to lower cholesterol and promote weight loss Stress reduction Increased physical activity (where appropriate)

29. Copyright © 2010 Pearson Education, Inc. Treatment of CAD and Myocardial Infarction Drug Treatment Drugs that reduce coagulation and therefore the risk of thrombosis, such as aspirin and coumadin Drugs that block sympathetic stimulation (propranolol or metoprolol) – for hypertension Drugs that cause vasodilation, such as nitroglycerin Drugs that block calcium movement into the cardiac and vascular smooth muscle cells (calcium channel blockers)

30. Copyright © 2010 Pearson Education, Inc. Coronary Artery Bypass Surgery (CABG) In a coronary artery bypass graft, a small section is removed from either a small artery or a peripheral vein and is used to create a detour around the obstructed portion of a coronary artery

31. Copyright © 2010 Pearson Education, Inc. Pathway of Blood Through the Heart The heart is two side-by-side pumps Equal volumes of blood are pumped to the pulmonary and systemic circuits Right side is the pump for the pulmonary circuit Vessels that carry blood to and from the lungs Pulmonary circuit is a short, low-pressure circulation Left side is the pump for the systemic circuit Vessels that carry the blood to and from all body tissues Systemic circuit blood encounters much resistance in the long pathways

32. Copyright © 2010 Pearson Education, Inc. Pathway of Blood Through the Heart and Lungs Vessels carry the blood through the circuits Arteries carry blood away from the heart Veins carry blood to the heart Capillaries permit exchange Right atrium  tricuspid valve  right ventricle Right ventricle  pulmonary semilunar valve  pulmonary arteries  lungs Lungs  pulmonary veins  left atrium Left atrium  bicuspid valve  left ventricle Left ventricle  aortic semilunar valve  aorta Aorta  systemic circulation Figure 18.5