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PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 18 The Cardiovascular.

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Presentation on theme: "PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 18 The Cardiovascular."— Presentation transcript:

1 PowerPoint ® Lecture Slides prepared by Janice Meeking, Mount Royal College C H A P T E R Copyright © 2010 Pearson Education, Inc. 18 The Cardiovascular System: The Heart: Part A

2 Copyright © 2010 Pearson Education, Inc. The Heart Beats over 100,000 times a day Normal Resting Heart Rate 60 – 100 beats per minute (too slow bradycardia – too fast tachycardia) 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

3 Copyright © 2010 Pearson Education, Inc. Figure 18.1a Point of maximal intensity (PMI) Diaphragm (a) Sternum 2nd rib Midsternal line PMI generally found at 4 th – 5 th ICS at midclavicular line

4 Copyright © 2010 Pearson Education, Inc. Figure 18.1c (c) Superior vena cava Left lung Aorta Parietal pleura (cut) Pericardium (cut) Pulmonary trunk Diaphragm Apex of heart

5 Copyright © 2010 Pearson Education, Inc. Pericardium Superficial fibrous pericardium Protects, anchors, and prevents overfilling (overdistention)

6 Copyright © 2010 Pearson Education, Inc. Pericardium Deep two-layered serous pericardium Parietal layer lines the internal surface of the fibrous pericardium Visceral layer (epicardium) on external surface of the heart Separated by fluid-filled pericardial cavity (decreases friction)

7 Copyright © 2010 Pearson Education, Inc. Figure 18.2 Fibrous pericardium Parietal layer of serous pericardium Pericardial cavity Epicardium (visceral layer of serous pericardium) Myocardium Endocardium Pulmonary trunk Heart chamber Heart wall Pericardium Myocardium

8 Copyright © 2010 Pearson Education, Inc. Layers of the Heart Wall 1.Epicardium—visceral layer of the serous pericardium

9 Copyright © 2010 Pearson Education, Inc. Layers of the Heart Wall 2.Myocardium Spiral bundles of cardiac muscle cells Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue Anchors cardiac muscle fibers Supports great vessels and valves Limits spread of action potentials to specific paths

10 Copyright © 2010 Pearson Education, Inc. Layers of the Heart Wall 3.Endocardium is continuous with endothelial lining of blood vessels

11 Copyright © 2010 Pearson Education, Inc. Figure 18.2 Fibrous pericardium Parietal layer of serous pericardium Pericardial cavity Epicardium (visceral layer of serous pericardium) Myocardium Endocardium Pulmonary trunk Heart chamber Heart wall Pericardium Myocardium

12 Copyright © 2010 Pearson Education, Inc. Figure 18.3 Cardiac muscle bundles

13 Copyright © 2010 Pearson Education, Inc. Chambers Four chambers Two atria Separated internally by the interatrial septum Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles Auricles increase atrial volume

14 Copyright © 2010 Pearson Education, Inc. Chambers Two ventricles Separated by the interventricular septum Anterior and posterior interventricular sulci mark the position of the septum externally

15 Copyright © 2010 Pearson Education, Inc. Figure 18.4b (b) Anterior view Brachiocephalic trunk Superior vena cava Right pulmonary artery Ascending aorta Pulmonary trunk Right pulmonary veins Right atrium Right coronary artery (in coronary sulcus) Anterior cardiac vein Right ventricle Right marginal artery Small cardiac vein Inferior vena cava Left common carotid artery Left subclavian artery Ligamentum arteriosum Left pulmonary artery Left pulmonary veins Circumflex artery Left coronary artery (in coronary sulcus) Left ventricle Great cardiac vein Anterior interventricular artery (in anterior interventricular sulcus) Apex Aortic arch Auricle of left atrium

16 Copyright © 2010 Pearson Education, Inc. Atria: The Receiving Chambers Walls are ridged by pectinate muscles Vessels entering right atrium Superior vena cava Inferior vena cava Coronary sinus Vessels entering left atrium Right and left pulmonary veins

17 Copyright © 2010 Pearson Education, Inc. Ventricles: The Discharging Chambers Walls are ridged by trabeculae carneae Papillary muscles project into the ventricular cavities Vessel leaving the right ventricle Pulmonary trunk Vessel leaving the left ventricle Aorta

18 Copyright © 2010 Pearson Education, Inc. Figure 18.4e Aorta Left pulmonary artery Left atrium Left pulmonary veins Mitral (bicuspid) valve Aortic valve Pulmonary valve Left ventricle Papillary muscle Interventricular septum Epicardium Myocardium Endocardium (e) Frontal section Superior vena cava Right pulmonary artery Pulmonary trunk Right atrium Right pulmonary veins Fossa ovalis Pectinate muscles Tricuspid valve Right ventricle Chordae tendineae Trabeculae carneae Inferior vena cava

19 Copyright © 2010 Pearson Education, Inc. Pathway of Blood Through the Heart The heart is two side-by-side pumps Right side is the pump for the pulmonary circuit Vessels that carry blood to and from the lungs Left side is the pump for the systemic circuit Vessels that carry the blood to and from all body tissues

20 Copyright © 2010 Pearson Education, Inc. Figure 18.5 Oxygen-rich, CO 2 -poor blood Oxygen-poor, CO 2 -rich blood Capillary beds of lungs where gas exchange occurs Capillary beds of all body tissues where gas exchange occurs Pulmonary veins Pulmonary arteries Pulmonary Circuit Systemic Circuit Aorta and branches Left atrium Heart Left ventricle Right atrium Right ventricle Venae cavae

21 Copyright © 2010 Pearson Education, Inc. Pathway of Blood Through the Heart Right atrium  tricuspid valve  right ventricle Right ventricle  pulmonary semilunar valve  pulmonary trunk  pulmonary arteries  lungs PLAY Animation: Rotatable heart (sectioned)

22 Copyright © 2010 Pearson Education, Inc. PLAY Animation: Rotatable heart (sectioned) Pathway of Blood Through the Heart Lungs  pulmonary veins  left atrium Left atrium  bicuspid valve  left ventricle Left ventricle  aortic semilunar valve  aorta Aorta  systemic circulation

23 Copyright © 2010 Pearson Education, Inc. Pathway of Blood Through the Heart Equal volumes of blood are pumped to the pulmonary and systemic circuits Pulmonary circuit is a short, low-pressure circulation Systemic circuit blood encounters much resistance in the long pathways Anatomy of the ventricles reflects these differences

24 Copyright © 2010 Pearson Education, Inc. Figure 18.6 Right ventricle Left ventricle Interventricular septum

25 Copyright © 2010 Pearson Education, Inc. Coronary Circulation The functional blood supply to the heart muscle itself Arterial supply varies considerably and contains many anastomoses (junctions) among branches Collateral routes provide additional routes for blood delivery

26 Copyright © 2010 Pearson Education, Inc. Coronary Circulation Arteries Right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries Veins Small cardiac, anterior cardiac, and great cardiac veins

27 Copyright © 2010 Pearson Education, Inc. Figure 18.7a Right ventricle Right coronary artery Right atrium Right marginal artery Posterior interventricular artery Anterior interventricular artery Circumflex artery Left coronary artery Aorta Anastomosis (junction of vessels) Left ventricle Superior vena cava (a) The major coronary arteries Left atrium Pulmonary trunk

28 Copyright © 2010 Pearson Education, Inc. Figure 18.7b Superior vena cava Anterior cardiac veins Small cardiac vein Middle cardiac vein Great cardiac vein Coronary sinus (b) The major cardiac veins

29 Copyright © 2010 Pearson Education, Inc. Figure 18.4d (d) Posterior surface view Aorta Left pulmonary artery Left pulmonary veins Auricle of left atrium Left atrium Great cardiac vein Posterior vein of left ventricle Left ventricle Apex Superior vena cava Right pulmonary artery Right pulmonary veins Right atrium Inferior vena cava Right coronary artery (in coronary sulcus) Coronary sinus Posterior interventricular artery (in posterior interventricular sulcus) Middle cardiac vein Right ventricle

30 Copyright © 2010 Pearson Education, Inc. Homeostatic Imbalances Angina pectoris Thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium Cells are weakened Myocardial infarction (heart attack) Prolonged coronary blockage Areas of cell death are repaired with noncontractile scar tissue

31 Copyright © 2010 Pearson Education, Inc. Heart Valves Ensure unidirectional blood flow through the heart Atrioventricular (AV) valves Prevent backflow into the atria when ventricles contract Tricuspid valve (right) Mitral valve (left) Chordae tendineae anchor AV valve cusps to papillary muscles

32 Copyright © 2010 Pearson Education, Inc. Heart Valves Semilunar (SL) valves Prevent backflow into the ventricles when ventricles relax Aortic semilunar valve Pulmonary semilunar valve

33 Copyright © 2010 Pearson Education, Inc. Figure 18.8a Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Tricuspid (right atrioventricular) valve Mitral (left atrioventricular) valve Aortic valve Pulmonary valve (b) Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Tricuspid (right atrioventricular) valve (a) Mitral (left atrioventricular) valve Aortic valve Pulmonary valve Fibrous skeleton Anterior

34 Copyright © 2010 Pearson Education, Inc. Figure 18.8b Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Tricuspid (right atrioventricular) valve Mitral (left atrioventricular) valve Aortic valve Pulmonary valve (b)

35 Copyright © 2010 Pearson Education, Inc. Figure 18.8c Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Chordae tendineae attached to tricuspid valve flap Papillary muscle (c)

36 Copyright © 2010 Pearson Education, Inc. Figure 18.8d Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Mitral valve Chordae tendineae Interventricular septum Myocardium of left ventricle Opening of inferior vena cava Tricuspid valve Papillary muscles Myocardium of right ventricle (d)

37 Copyright © 2010 Pearson Education, Inc. Figure 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)

38 Copyright © 2010 Pearson Education, Inc. Figure 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

39 Copyright © 2010 Pearson Education, Inc. Histology and Physiology of Cardiac Muscle

40 Copyright © 2010 Pearson Education, Inc. Requirements of Cardiac Muscle 1. Have considerable endurance – the heart beats over 100,000 beats per day (75 beats per minute x 1440 minutes in a day) 2.Both atria must contract as one unit and both ventricles must contract as one unit – even though they are made of separate individual small cells (cells can only get so big due to the surface to volume relationship problem)

41 Copyright © 2010 Pearson Education, Inc. Endurance 1.The cardiac muscle cells are smaller than skeletal muscle cells giving good surface to volume relationship- thus allowing more oxygen and nutrients to enter and waste to leave 2.More myoglobin – red substance akin to hemoglobin that holds reserve oxygen in the cell (more myoglobin than dark – endurance skeletal muscle) 3.Slow ATPase – the faster ATP is broken down the more energy that is loss as heat instead being put to good use. Thus the slower ATP is broken down to ADP – more useful energy that is harnessed. 4.Heart muscle uses almost exclusively aerobic metabolism (cannot tolerate too much ischemia)– but can burn lactic acid released by skeletal muscle 5.Lots of mitochondria

42 Copyright © 2010 Pearson Education, Inc. Cardiac Muscle must have better endurance than long endurance skeletal muscle

43 Copyright © 2010 Pearson Education, Inc. Cardiac Metabolism The heart is so tuned to aerobic metabolism that it is unable to pump sufficiently in ischemic conditions. At basal metabolic rates, about 1% of energy is derived from anaerobic metabolism. This can increase to 10% under moderately hypoxic conditions, but, under more severe hypoxic conditions, not enough energy can be liberated by lactate production to sustain ventricular contractions. Under basal aerobic conditions, 60% of energy comes from fat (free fatty acids and triglycerides), 35% from carbohydrates, and 5% from amino acids and ketone bodies. However, these proportions vary widely according to nutritional state. For example, during starvation, lactate can be recycled by the heart.

44 Copyright © 2010 Pearson Education, Inc. Atria and Ventricles Must act as single Units It is essential that both atria must contract at the same time in order to adequately squeeze the blood into the two ventricles. Likewise it is important for both ventricles to contract at the same time in order to adequately squeeze the both into their respective outflow pipes (pulmonary artery from right ventricle and aorta from left ventricle) The problem is that the atria and ventricles must be comprised of several small cells and not one big cell for the atria and one for the ventricles – thus the individual cells must physiologically lock together to form a physiologic unit – syncytium.

45 Copyright © 2010 Pearson Education, Inc. Cardiac muscle cell mechanisms to form a syncytium 1.Cardiac muscle cells are branched – the anatomical feature allows the action potential signals to travel along several branches at the same time going to several cardiac muscle cells at the same time and those cells in turn branch doing the same thing. 2.Hook the cells together by gap junctions – the intercellular connection allows faster travel of impulses between the cells.

46 Copyright © 2010 Pearson Education, Inc. Microscopic Anatomy of Cardiac Muscle Cardiac muscle cells are striated, short, fat, branched, and interconnected Connective tissue matrix (endomysium) connects to the fibrous skeleton T tubules are wide but less numerous; SR is simpler than in skeletal muscle (more dependence on extracellular calcium) Numerous large mitochondria (25–35% of cell volume)

47 Copyright © 2010 Pearson Education, Inc. Table 9.3.1

48 Copyright © 2010 Pearson Education, Inc. Cardiac Muscle Cell Intercellular Connections Intercalated discs: junctions between cells anchor cardiac cells Desmosomes prevent cells from separating during contraction Gap junctions allow ions to pass; electrically couple adjacent cells Heart muscle behaves as a functional syncytium

49 Copyright © 2010 Pearson Education, Inc. Figure 18.11a Nucleus DesmosomesGap junctions Intercalated discsCardiac muscle cell (a) Light microscope see intercalated discs In Electron Microscope can resolute Intercalated Discs into Gap junctions And Desmosomes

50 Copyright © 2010 Pearson Education, Inc. Figure 18.11b Nucleus I band A band Cardiac muscle cell Sarcolemma Z disc Mitochondrion T tubule Sarcoplasmic reticulum I band Intercalated disc (b)


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