The Pulmonary and Systemic Circuits Heart is transport system; two side-by-side pumps Right side receives oxygen-poor blood from tissues Pumps to lungs to get rid of CO2, pick up O2, via pulmonary circuit Left side receives oxygenated blood from lungs Pumps to body tissues via systemic circuit © 2013 Pearson Education, Inc.

The Pulmonary and Systemic Circuits Receiving chambers of heart: Right atrium Receives blood returning from systemic circuit Left atrium Receives blood returning from pulmonary circuit © 2013 Pearson Education, Inc.

The Pulmonary and Systemic Circuits Pumping chambers of heart: Right ventricle Pumps blood through pulmonary circuit Left ventricle Pumps blood through systemic circuit © 2013 Pearson Education, Inc.

Figure 18.1 The systemic and pulmonary circuits. Capillary beds of lungs where gas exchange occurs Pulmonary Circuit Pulmonary arteries Pulmonary veins Aorta and branches Venae cavae Left atrium Left ventricle Right atrium Heart Right ventricle Systemic Circuit Capillary beds of all body tissues where gas exchange occurs Oxygen-rich, CO2-poor blood Oxygen-poor, CO2-rich blood © 2013 Pearson Education, Inc.

Approximately size of fist Location: Heart Anatomy Approximately size of fist Location: In mediastinum between second rib and fifth intercostal space On superior surface of diaphragm Two-thirds of heart to left of midsternal line Anterior to vertebral column, posterior to sternum © 2013 Pearson Education, Inc.

Base (posterior surface) leans toward right shoulder Heart Anatomy Base (posterior surface) leans toward right shoulder Apex points toward left hip Apical impulse palpated between fifth and sixth ribs, just below left nipple © 2013 Pearson Education, Inc.

Figure 18.2a Location of the heart in the mediastinum. Midsternal line 2nd rib Sternum Diaphragm Location of apical impulse © 2013 Pearson Education, Inc.

Figure 18.2b Location of the heart in the mediastinum. Left lung Body of T7 vertebra Posterior © 2013 Pearson Education, Inc. 8

Figure 18.2c Location of the heart in the mediastinum. Superior vena cava Aorta Parietal pleura (cut) Pulmonary trunk Left lung Pericardium (cut) Apex of heart Diaphragm © 2013 Pearson Education, Inc.

Coverings of the Heart: Pericardium Double-walled sac Superficial fibrous pericardium Protects, anchors to surrounding structures, and prevents overfilling © 2013 Pearson Education, Inc.

Deep two-layered serous pericardium Parietal layer lines internal surface of fibrous pericardium Visceral layer (epicardium) on external surface of heart Two layers separated by fluid-filled pericardial cavity (decreases friction) © 2013 Pearson Education, Inc.

Figure 18.3 The pericardial layers and layers of the heart wall. Pulmonary trunk Fibrous pericardium Parietal layer of serous pericardium Pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous pericardium) Heart wall Myocardium Endocardium Heart chamber © 2013 Pearson Education, Inc.

Homeostatic Imbalance Pericarditis Inflammation of pericardium Roughens membrane surfaces  pericardial friction rub (creaking sound) heard with stethoscope Cardiac tamponade Excess fluid sometimes compresses heart  limited pumping ability © 2013 Pearson Education, Inc.

Layers of the Heart Wall Three layers of heart wall: Epicardium Myocardium Endocardium Visceral layer of serous pericardium © 2013 Pearson Education, Inc.

Layers of the Heart Wall Myocardium Spiral bundles of contractile cardiac muscle cells Cardiac skeleton: crisscrossing, interlacing layer of connective tissue Anchors cardiac muscle fibers Supports great vessels and valves Limits spread of action potentials to specific paths © 2013 Pearson Education, Inc.

Layers of the Heart Wall Endocardium continuous with endothelial lining of blood vessels Lines heart chambers; covers cardiac skeleton of valves © 2013 Pearson Education, Inc.

Figure 18.3 The pericardial layers and layers of the heart wall. Pulmonary trunk Fibrous pericardium Parietal layer of serous pericardium Pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous pericardium) Heart wall Myocardium Endocardium Heart chamber © 2013 Pearson Education, Inc.

Cardiac muscle bundles Figure 18.4 The circular and spiral arrangement of cardiac muscle bundles in the myocardium of the heart. Cardiac muscle bundles © 2013 Pearson Education, Inc.

Interatrial septum – separates atria Chambers Four chambers: Two superior atria Two inferior ventricles Interatrial septum – separates atria Fossa ovalis – remnant of foramen ovale of fetal heart Interventricular septum – separates ventricles © 2013 Pearson Education, Inc.

Figure 18.5e Gross anatomy of the heart. Aorta Left pulmonary artery Superior vena cava Left atrium Right pulmonary artery Left pulmonary veins Pulmonary trunk Right atrium Mitral (bicuspid) valve Right pulmonary veins Fossa ovalis Aortic valve Pectinate muscles Pulmonary valve Tricuspid valve Left ventricle Right ventricle Papillary muscle Chordae tendineae Interventricular septum Trabeculae carneae Epicardium Inferior vena cava Myocardium Endocardium Frontal section © 2013 Pearson Education, Inc.

Chambers and Associated Great Vessels Coronary sulcus (atrioventricular groove) Encircles junction of atria and ventricles Anterior interventricular sulcus Anterior position of interventricular septum Posterior interventricular sulcus Landmark on posteroinferior surface © 2013 Pearson Education, Inc.

Atria: The Receiving Chambers Auricles Appendages that increase atrial volume Right atrium Pectinate muscles Posterior and anterior regions separated by crista terminalis Left atrium Pectinate muscles only in auricles © 2013 Pearson Education, Inc.

Atria: The Receiving Chambers Small, thin-walled Contribute little to propulsion of blood Three veins empty into right atrium: Superior vena cava, inferior vena cava, coronary sinus Four pulmonary veins empty into left atrium © 2013 Pearson Education, Inc.

Ventricles: The Discharging Chambers Most of the volume of heart Right ventricle - most of anterior surface Left ventricle – posteroinferior surface Trabeculae carneae – irregular ridges of muscle on walls Papillary muscles – anchor chordae tendineae © 2013 Pearson Education, Inc.

Ventricles: The Discharging Chambers Thicker walls than atria Actual pumps of heart Right ventricle Pumps blood into pulmonary trunk Left ventricle Pumps blood into aorta (largest artery in body) © 2013 Pearson Education, Inc.

Figure 18.5b Gross anatomy of the heart. Left common carotid artery Brachiocephalic trunk Left subclavian artery Superior vena cava Aortic arch Ligamentum arteriosum Right pulmonary artery Left pulmonary artery Ascending aorta Left pulmonary veins Pulmonary trunk Auricle of left atrium Right pulmonary veins Circumflex artery Right atrium Right coronary artery (in coronary sulcus) Left coronary artery (in coronary sulcus) Anterior cardiac vein Left ventricle Right ventricle Right marginal artery Great cardiac vein Anterior interventricular artery (in anterior interventricular sulcus) Small cardiac vein Inferior vena cava Apex Anterior view © 2013 Pearson Education, Inc.

Figure 18.5a Gross anatomy of the heart. Aortic arch (fat covered) Pulmonary trunk Auricle of right atrium Auricle of left atrium Anterior interventricular artery Right ventricle Apex of heart (left ventricle) Anterior aspect (pericardium removed) © 2013 Pearson Education, Inc.

Figure 18.5f Gross anatomy of the heart. Ascending aorta (cut open) Superior vena cava Pulmonary trunk Aortic valve Right ventricle anterior wall (retracted) Pulmonary valve Trabeculae carneae Interventricular septum (cut) Opening to right atrium Left ventricle Papillary muscles Chordae tendineae Right ventricle Photograph; view similar to (e) © 2013 Pearson Education, Inc.

Heart Valves Ensure unidirectional blood flow through heart Open and close in response to pressure changes Two atrioventricular (AV) valves Prevent backflow into atria when ventricles contract Tricuspid valve (right AV valve) Mitral valve (left AV valve, bicuspid valve) Chordae tendineae anchor cusps to papillary muscles Hold valve flaps in closed position © 2013 Pearson Education, Inc.

Figure 18.7 The atrioventricular (AV) valves. Blood returning to the heart fills atria, pressing against the AV valves. The increased pressure forces AV valves open. 1 Direction of blood flow Atrium Cusp of atrioventricular valve (open) As ventricles fill, AV valve flaps hang limply into ventricles. 2 Chordae tendineae Atria contract, forcing additional blood into ventricles. 3 Papillary muscle Ventricle AV valves open; atrial pressure greater than ventricular pressure Atrium Cusps of atrioventricular valve (closed) Ventricles contract, forcing blood against AV valve cusps. 1 2 AV valves close. Blood in ventricle Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria. 3 AV valves closed; atrial pressure less than ventricular pressure © 2013 Pearson Education, Inc.

Two semilunar (SL) valves Heart Valves Two semilunar (SL) valves Prevent backflow into ventricles when ventricles relax Open and close in response to pressure changes Aortic semilunar valve Pulmonary semilunar valve © 2013 Pearson Education, Inc.

Figure 18.8 The semilunar (SL) valves. Aorta Pulmonary trunk As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open. Semilunar valves open As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close. Semilunar valves closed © 2013 Pearson Education, Inc.

(left atrioventricular) valve Figure 18.6a Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Mitral (left atrioventricular) valve Tricuspid (right atrioventricular) valve Aortic valve Pulmonary valve Cardiac skeleton Anterior © 2013 Pearson Education, Inc.

(left atrioventricular) valve Figure 18.6b Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Mitral (left atrioventricular) valve Tricuspid (right atrioventricular) valve Aortic valve Pulmonary valve © 2013 Pearson Education, Inc.

Chordae tendineae attached to tricuspid valve flap Papillary muscle Figure 18.6c Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Chordae tendineae attached to tricuspid valve flap Papillary muscle © 2013 Pearson Education, Inc.

Pulmonary valve Aortic valve Area of cutaway Mitral valve Figure 18.6d Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Opening of inferior vena cava Mitral valve Chordae tendineae Tricuspid valve Myocardium of right ventricle Interventricular septum Papillary muscles Myocardium of left ventricle © 2013 Pearson Education, Inc.

Homeostatic Imbalance Two conditions severely weaken heart: Incompetent valve Blood backflows so heart repumps same blood over and over Valvular stenosis Stiff flaps – constrict opening  heart must exert more force to pump blood Valve replaced with mechanical, animal, or cadaver valve © 2013 Pearson Education, Inc.

Pathway of Blood Through the Heart Pulmonary circuit Right atrium  tricuspid valve  right ventricle Right ventricle  pulmonary semilunar valve  pulmonary trunk  pulmonary arteries  lungs Lungs  pulmonary veins  left atrium © 2013 Pearson Education, Inc.

Pathway of Blood Through the Heart Systemic circuit Left atrium  mitral valve  left ventricle Left ventricle  aortic semilunar valve  aorta Aorta  systemic circulation © 2013 Pearson Education, Inc.

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 1 Both sides of the heart pump at the same time, but let’s follow one spurt of blood all the way through the system. Oxygen-poor blood Oxygen-rich blood Pulmonary Semilunar valve Tricuspid valve Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Right atrium Right ventricle Pulmonary trunk Pulmonary arteries SVC Tricuspid valve Coronary sinus Pulmonary trunk Right atrium Pulmonary semilunar valve Right ventricle IVC Oxygen-poor blood is carried in two pulmonary arteries to the lungs (pulmonary circuit) to be oxygenated. Oxygen-poor blood returns from the body tissues back to the heart. To heart To lungs Systemic capillaries Pulmonary capillaries Oxygen-rich blood is delivered to the body tissues (systemic circuit). Oxygen-rich blood returns to the heart via the four pulmonary veins. To body To heart Aorta Pulmonary veins Aortic semilunar valve Mitral valve Left atrium Left ventricle Aortic Semilunar valve Mitral valve Four pulmonary veins Left ventricle Left atrium Aorta © 2013 Pearson Education, Inc.

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 2 Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Oxygen-poor blood Oxygen-rich blood SVC Coronary sinus IVC © 2013 Pearson Education, Inc. 41

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 3 Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Oxygen-poor blood Right atrium Oxygen-rich blood SVC Coronary sinus Right atrium IVC © 2013 Pearson Education, Inc. 42

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 4 Tricuspid valve Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Right atrium Right ventricle Oxygen-poor blood Oxygen-rich blood SVC Tricuspid valve Coronary sinus Right atrium Right ventricle IVC © 2013 Pearson Education, Inc. 43

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 5 Pulmonary Semilunar valve Tricuspid valve Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Right atrium Right ventricle Pulmonary trunk Oxygen-poor blood Oxygen-rich blood Pulmonary arteries SVC Coronary sinus Tricuspid valve Pulmonary trunk Right atrium Pulmonary semilunar valve Right ventricle IVC © 2013 Pearson Education, Inc. 44

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 6 Oxygen-poor blood Pulmonary Semilunar valve Oxygen-rich blood Tricuspid valve Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Right atrium Right ventricle Pulmonary trunk Pulmonary arteries SVC Coronary sinus Tricuspid valve Pulmonary trunk Right atrium Pulmonary semilunar valve Right ventricle IVC Oxygen-poor blood is carried in two pulmonary arteries to the lungs (pulmonary circuit) to be oxygenated. To lungs Pulmonary capillaries © 2013 Pearson Education, Inc. 45

Pulmonary veins Four pulmonary veins Oxygen-poor blood Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 7 Oxygen-poor blood Pulmonary veins Oxygen-rich blood Four pulmonary veins © 2013 Pearson Education, Inc. 46

Blood Flow Through the Heart Figure 18.9 The heart is a double pump, each side supplying its own circuit. Oxygen-poor blood Slide 8 Blood Flow Through the Heart Oxygen-rich blood Pulmonary veins Right ventricle Left atrium Four pulmonary veins Left atrium © 2013 Pearson Education, Inc. 47

Oxygen-rich blood Mitral valve Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 9 Oxygen-poor blood Oxygen-rich blood Pulmonary veins Left atrium Mitral valve Left ventricle Mitral valve Four pulmonary veins Left ventricle Left atrium © 2013 Pearson Education, Inc. 48

Oxygen-rich blood Aortic Semilunar valve Mitral valve Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 10 Oxygen-poor blood Oxygen-rich blood Right ventricle Aorta Pulmonary veins Aortic semilunar valve Left atrium Mitral valve Left ventricle Aortic Semilunar valve Mitral valve Four pulmonary veins Left ventricle Left atrium Aorta © 2013 Pearson Education, Inc. 49

Blood Flow Through the Heart Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 11 Blood Flow Through the Heart Oxygen-poor blood Oxygen-rich blood Systemic capillaries Oxygen-rich blood is delivered to the body tissues (systemic circuit). To body Aorta Pulmonary veins Aortic semilunar valve Left atrium Mitral valve Left ventricle Aortic Semilunar valve Mitral valve Four pulmonary veins Left ventricle Left atrium Aorta © 2013 Pearson Education, Inc. 50

Superior vena cava (SVC) Inferior vena cava (IVC) Figure 18.9 The heart is a double pump, each side supplying its own circuit. Slide 12 Both sides of the heart pump at the same time, but let’s follow one spurt of blood all the way through the system. Oxygen-poor blood Oxygen-rich blood Pulmonary Semilunar valve Tricuspid valve Superior vena cava (SVC) Inferior vena cava (IVC) Coronary sinus Right atrium Right ventricle Pulmonary trunk Pulmonary arteries SVC Tricuspid valve Coronary sinus Pulmonary trunk Right atrium Pulmonary semilunar valve Right ventricle IVC Oxygen-poor blood is carried in two pulmonary arteries to the lungs (pulmonary circuit) to be oxygenated. Oxygen-poor blood returns from the body tissues back to the heart. To heart To lungs Systemic capillaries Pulmonary capillaries Oxygen-rich blood is delivered to the body tissues (systemic circuit). Oxygen-rich blood returns to the heart via the four pulmonary veins. To body To heart Aorta Pulmonary veins Aortic semilunar valve Mitral valve Left atrium Left ventricle Aortic Semilunar valve Mitral valve Four pulmonary veins Left ventricle Left atrium Aorta © 2013 Pearson Education, Inc. 51

Pathway of Blood Through the Heart Equal volumes of blood pumped to pulmonary and systemic circuits Pulmonary circuit short, low-pressure circulation Systemic circuit long, high-friction circulation Anatomy of ventricles reflects differences Left ventricle walls 3X thicker than right Pumps with greater pressure © 2013 Pearson Education, Inc.

Left Right ventricle Interventricular septum Figure 18.10 Anatomical differences between the right and left ventricles. Right ventricle Interventricular septum Left © 2013 Pearson Education, Inc.

Functional blood supply to heart muscle itself Coronary Circulation Functional blood supply to heart muscle itself Delivered when heart relaxed Left ventricle receives most blood supply Arterial supply varies among individuals Contains many anastomoses (junctions) Provide additional routes for blood delivery Cannot compensate for coronary artery occlusion © 2013 Pearson Education, Inc.

Coronary Circulation: Arteries Arteries arise from base of aorta Left coronary artery branches  anterior interventricular artery and circumflex artery Supplies interventricular septum, anterior ventricular walls, left atrium, and posterior wall of left ventricle Right coronary artery branches  right marginal artery and posterior interventricular artery Supplies right atrium and most of right ventricle © 2013 Pearson Education, Inc.

Figure 18.11a Coronary circulation. Aorta Superior vena cava Anastomosis (junction of vessels) Right atrium coronary artery ventricle marginal Posterior interventricular Anterior Left Circumflex Left atrium Pulmonary trunk The major coronary arteries © 2013 Pearson Education, Inc.

Coronary Circulation: Veins Cardiac veins collect blood from capillary beds Coronary sinus empties into right atrium; formed by merging cardiac veins Great cardiac vein of anterior interventricular sulcus Middle cardiac vein in posterior interventricular sulcus Small cardiac vein from inferior margin Several anterior cardiac veins empty directly into right atrium anteriorly © 2013 Pearson Education, Inc.

Figure 18.11b Coronary circulation. Superior vena cava Anterior cardiac veins Small cardiac vein Middle cardiac vein Coronary sinus Great vein The major cardiac veins © 2013 Pearson Education, Inc.

Figure 18.5d Gross anatomy of the heart. Aorta Superior vena cava Right pulmonary artery Left pulmonary artery Right pulmonary veins Left pulmonary veins Auricle of left atrium Right atrium Left atrium Inferior vena cava Great cardiac vein Coronary sinus Right coronary artery (in coronary sulcus) Posterior vein of left ventricle Posterior interventricular artery (in posterior interventricular sulcus) Left ventricle Middle cardiac vein Right ventricle Apex Posterior surface view © 2013 Pearson Education, Inc.

Homeostatic Imbalances Angina pectoris Thoracic pain caused by fleeting deficiency in blood delivery to myocardium Cells weakened Myocardial infarction (heart attack) Prolonged coronary blockage Areas of cell death repaired with noncontractile scar tissue © 2013 Pearson Education, Inc.