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2 An Introduction to the Cardiovascular SystemThe Pulmonary Circuit Carries blood to and from gas exchange surfaces of lungs The Systemic Circuit Carries blood to and from the body Blood alternates between pulmonary circuit and systemic circuit

3 An Introduction to the Cardiovascular SystemThree Types of Blood Vessels Arteries Carry blood away from heart Veins Carry blood to heart Capillaries Networks between arteries and veins

4 An Introduction to the Cardiovascular SystemCapillaries Also called exchange vessels Exchange materials between blood and tissues Materials include dissolved gases, nutrients, waste products

5 Figure 20-1 An Overview of the Cardiovascular System.Pulmonary Circuit Systemic Circuit Pulmonary arteries Systemic arteries Systemic veins Pulmonary veins Capillaries in head, neck, upper limbs Capillaries in lungs Right atrium Left atrium Right ventricle Left ventricle Capillaries in trunk and lower limbs

6 An Introduction to the Cardiovascular SystemFour Chambers of the Heart Right atrium Collects blood from systemic circuit Right ventricle Pumps blood to pulmonary circuit Left atrium Collects blood from pulmonary circuit Left ventricle Pumps blood to systemic circuit

7 20-1 Anatomy of the Heart The HeartGreat veins and arteries at the base Pointed tip is apex Surrounded by pericardial sac Sits between two pleural cavities in the mediastinum

8 Figure 20-2a The Location of the Heart in the Thoracic Cavity.Trachea Thyroid gland First rib (cut) Base of heart Right lung Left lung Parietal pericardium (cut) Apex of heart Diaphragm a An anterior view of the chest, showing the position of the heart and major blood vessels relative to the ribs, lungs, and diaphragm.

9 20-1 Anatomy of the Heart The PericardiumDouble lining of the pericardial cavity Visceral pericardium Inner layer of pericardium Parietal pericardium Outer layer Forms inner layer of pericardial sac

10 20-1 Anatomy of the Heart The Pericardium Pericardial cavityIs between parietal and visceral layers Contains pericardial fluid Pericardial sac Fibrous tissue Surrounds and stabilizes heart

11 Figure 20-2b The Location of the Heart in the Thoracic Cavity.Posterior mediastinum Aorta (arch segment removed) Esophagus Left pulmonary artery Right pleural cavity Left pleural cavity Right lung Left lung Bronchus of lung Left pulmonary vein Right pulmonary artery Pulmonary trunk Aortic arch Right pulmonary vein Left atrium Left ventricle Superior vena cava Pericardial cavity Right atrium Epicardium Right ventricle Pericardial sac Anterior mediastinum Sternum b A superior view of the organs in the mediastinum; portions of the lungs have been removed to reveal blood vessels and airways. The heart is located in the anterior part of the mediastinum, immediately posterior to the sternum.

12 Figure 20-2c The Location of the Heart in the Thoracic Cavity.Base of heart Cut edge of parietal pericardium Wrist (corresponds to base of heart) Fibrous tissue of pericardial sac Inner wall (corresponds to epicardium) Parietal pericardium Air space (corresponds to pericardial cavity) Areolar tissue Mesothelium Outer wall (corresponds to parietal pericardium) Cut edge of epicardium Fibrous attachment to diaphragm Apex of heart Balloon c The relationship between the heart and the pericardial cavity; compare with the fist-and-balloon example.

13 20-1 Anatomy of the Heart Superficial Anatomy of the Heart AtriaThin-walled Expandable outer auricle (atrial appendage)

14 20-1 Anatomy of the Heart Superficial Anatomy of the Heart SulciCoronary sulcus divides atria and ventricles Anterior interventricular sulcus and posterior interventricular sulcus Separate left and right ventricles Contain blood vessels of cardiac muscle

15 Figure 20-3a The Position and Superficial Anatomy of the Heart.Base of heart 1 1 Ribs 2 2 3 3 4 4 5 5 6 6 7 7 Apex of heart 8 8 9 9 10 10 a Heart position relative to the rib cage.

16 Figure 20-3b The Position and Superficial Anatomy of the Heart.Left subclavian artery Left common carotid artery Arch of aorta Ligamentum arteriosum Brachiocephalic trunk Ascending aorta Descending aorta Left pulmonary artery Superior vena cava Pulmonary trunk Auricle of right atrium Right atrium Auricle of left atrium Fat and vessels in anterior interventricular sulcus Right ventricle Fat and vessels in coronary sulcus Left ventricle b Major anatomical features on the anterior surface.

18 Figure 20-3d The Position and Superficial Anatomy of the Heart.Arch of aorta Left pulmonary artery Right pulmonary artery Left pulmonary veins Fat and vessels in coronary sulcus Superior vena cava Left atrium Coronary sinus Right pulmonary veins (superior and inferior) Right atrium Left ventricle Inferior vena cava Right ventricle Fat and vessels in posterior interventricular sulcus d Major landmarks on the posterior surface. Coronary arteries (which supply the heart itself) are shown in red; coronary veins are shown in blue.

19 20-1 Anatomy of the Heart The Heart Wall Epicardium MyocardiumEndocardium

20 Figure 20-5c Cardiac Muscle Cells.Intercalated discs Cardiac muscle tissue LM x 575 c Cardiac muscle tissue

21 20-1 Anatomy of the Heart Internal Anatomy and OrganizationInteratrial septum separates atria Interventricular septum separates ventricles

22 20-1 Anatomy of the Heart Internal Anatomy and OrganizationAtrioventricular (AV) valves Connect right atrium to right ventricle and left atrium to left ventricle Are folds of fibrous tissue that extend into openings between atria and ventricles Permit blood flow in one direction From atria to ventricles

23 20-1 Anatomy of the Heart The Right Atrium Superior vena cavaReceives blood from head, neck, upper limbs, and chest Inferior vena cava Receives blood from trunk, viscera, and lower limbs Coronary sinus Cardiac veins return blood to coronary sinus Coronary sinus opens into right atrium

24 20-1 Anatomy of the Heart The Right Atrium Foramen ovaleBefore birth, is an opening through interatrial septum Connects the two atria Seals off at birth, forming fossa ovalis

25 20-1 Anatomy of the Heart The Right Atrium Pectinate musclesContain prominent muscular ridges On anterior atrial wall and inner surfaces of right auricle

26 Figure 20-6a The Sectional Anatomy of the Heart.Left common carotid artery Brachiocephalic trunk Left subclavian artery Ligamentum arteriosum Superior vena cava Pulmonary trunk Aortic arch Pulmonary valve Right pulmonary arteries Left pulmonary arteries Ascending aorta Left pulmonary veins Fossa ovalis Left atrium Opening of coronary sinus Interatrial septum Aortic valve Right atrium Cusp of left AV (mitral) valve Pectinate muscles Conus arteriosus Left ventricle Cusp of right AV (tricuspid) valve Chordae tendineae Interventricular septum Papillary muscles Trabeculae carneae Right ventricle Inferior vena cava Moderator band Descending aorta a A diagrammatic frontal section through the heart, showing major landmarks and the path of blood flow (marked by arrows) through the atria, ventricles, and associated vessels.

27 Figure 20-6c The Sectional Anatomy of the Heart.Left subclavian artery Left common carotid artery Brachiocephalic trunk Superior vena cava Pulmonary trunk Ascending aorta Cusp of pulmonary valve Auricle of left atrium Right atrium Cusp of left AV (bicuspid) valve Chordae tendineae Papillary muscles Cusps of right AV (tricuspid) valve Left ventricle Trabeculae carneae Interventricular septum Right ventricle c Anterior view of a frontally sectioned heart showing internal features and valves.

28 20-1 Anatomy of the Heart The Right VentricleFree edges attach to chordae tendineae from papillary muscles of ventricle Prevent valve from opening backward Right atrioventricular (AV) valve Also called tricuspid valve Opening from right atrium to right ventricle Has three cusps Prevents backflow

30 20-1 Anatomy of the Heart The Pulmonary CircuitPulmonary trunk divides into left and right pulmonary arteries Blood flows from right ventricle to pulmonary trunk through pulmonary valve Pulmonary valve has three semilunar cusps

31 20-1 Anatomy of the Heart The Left AtriumBlood gathers into left and right pulmonary veins Pulmonary veins deliver to left atrium Blood from left atrium passes to left ventricle through left atrioventricular (AV) valve A two-cusped bicuspid valve or mitral valve

32 20-1 Anatomy of the Heart The Left Ventricle Systemic circulationBlood leaves left ventricle through aortic valve into ascending aorta Ascending aorta turns (aortic arch) and becomes descending aorta

34 Figure 20-7a Structural Differences between the Left and Right Ventricles.Posterior interventricular sulcus Left ventricle Right ventricle Fat in anterior interventricular sulcus a A diagrammatic sectional view through the heart, showing the relative thicknesses of the two ventricles. Notice the pouchlike shape of the right ventricle and the greater thickness of the left ventricle.

36 Figure 20-8a Valves of the Heart (Part 2 of 2).Frontal Sections through Left Atrium and Ventricle Pulmonary veins LEFT ATRIUM Left AV (bicuspid) valve (open) Chordae tendineae (loose) Relaxed ventricles Aortic valve (closed) Papillary muscles (relaxed) LEFT VENTRICLE (relaxed and filling with blood) a When the ventricles are relaxed, the AV valves are open and the semilunar valves are closed. The chordae tendineae are loose, and the papillary muscles are relaxed.

38 Figure 20-8b Valves of the Heart (Part 2 of 2).Aorta LEFT ATRIUM Aortic sinus Left AV (bicuspid) valve (closed) Aortic valve (open) Chordae tendineae (tense) Contracting ventricles Papillary muscles (contracted) Left ventricle (contracted) b 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.

39 20-1 Anatomy of the Heart The Blood Supply to the Heart= Coronary circulation Supplies blood to muscle tissue of heart Coronary arteries and cardiac veins

40 20-1 Anatomy of the Heart The Coronary Arteries Left and rightOriginate at aortic sinuses High blood pressure, elastic rebound forces blood through coronary arteries between contractions

41 20-1 Anatomy of the Heart Right Coronary Artery Supplies blood to:Right atrium Portions of both ventricles Cells of sinoatrial (SA) and atrioventricular nodes Marginal arteries (surface of right ventricle) Posterior interventricular artery

42 20-1 Anatomy of the Heart Left Coronary Artery Supplies blood to:Left ventricle Left atrium Interventricular septum

43 20-1 Anatomy of the Heart Two Main Branches of Left Coronary ArteryCircumflex artery Anterior interventricular artery Arterial Anastomoses Interconnect anterior and posterior interventricular arteries Stabilize blood supply to cardiac muscle

44 20-1 Anatomy of the Heart The Cardiac Veins Great cardiac veinDrains blood from area of anterior interventricular artery into coronary sinus Anterior cardiac veins Empty into right atrium Posterior cardiac vein, middle cardiac vein, and small cardiac vein Empty into great cardiac vein or coronary sinus

45 Figure 20-9a The Coronary Circulation.Aortic arch Left coronary artery Ascending aorta Pulmonary trunk Circumflex artery Right coronary artery Anterior interventricular artery Atrial arteries Great cardiac vein Anterior cardiac veins Small cardiac vein Marginal artery a Coronary vessels supplying and draining the anterior surface of the heart.

46 Figure 20-9b The Coronary Circulation.Coronary sinus Circumflex artery Great cardiac vein Marginal artery Posterior interventricular artery Posterior cardiac vein Small cardiac vein Left ventricle Right coronary artery Middle cardiac vein Marginal artery b Coronary vessels supplying and draining the posterior surface of the heart.

48 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseCoronary artery disease (CAD) Areas of partial or complete blockage of coronary circulation Cardiac muscle cells need a constant supply of oxygen and nutrients Usual cause is formation of a fatty deposit, or atherosclerotic plaque, in the wall of a coronary vessel

49 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseMyocardial 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)

50 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseTreatment 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)

51 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseTreatment 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) Drugs that cause vasodilation, such as nitroglycerin Drugs that block calcium movement into the cardiac and vascular smooth muscle cells (calcium channel blockers) In a myocardial infarction, drugs to relieve pain, fibrinolytic agents to help dissolve clots, and oxygen

52 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarction Noninvasive surgery Atherectomy Blockage by a single, soft plaque may be reduced with the aid of a long, slender catheter inserted into a coronary artery to the plaque

53 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarction Noninvasive surgery Balloon angioplasty The tip of the catheter contains an inflatable balloon Once in position, the balloon is inflated, pressing the plaque against the vessel walls Because plaques commonly redevelop after angioplasty, a fine tubular wire mesh called a stent may be inserted into the vessel, holding it open

54 20-1 Anatomy of the Heart Heart Disease – Coronary Artery DiseaseTreatment of CAD and myocardial infarction Coronary artery bypass graft (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 As many as four coronary arteries can be rerouted this way during a single operation The procedures are named according to the number of vessels repaired, so we speak of single, double, triple, or quadruple coronary bypasses

55 Figure 20-10 Heart Disease and Heart Attacks (Part 1 of 4).Advanced Coronary Artery Disease A color-enhanced DSA scan showing advanced coronary artery disease. Blood flow to the ventricular myocardium is severely restricted. Normal Heart A color-enhanced digital subtraction angiography (DSA) scan of a normal heart.

56 20-2 The Conducting SystemHeartbeat A single contraction of the heart The entire heart contracts in series First the atria Then the ventricles

57 20-2 The Conducting SystemThe Cardiac Cycle Begins with action potential at SA node Transmitted through conducting system Produces action potentials in cardiac muscle cells (contractile cells) Electrocardiogram (ECG or EKG) Electrical events in the cardiac cycle can be recorded on an electrocardiogram

58 20-2 The Conducting SystemStructures of the Conducting System Sinoatrial (SA) node – wall of right atrium Atrioventricular (AV) node – junction between atria and ventricles Conducting cells – throughout myocardium

59 Figure 20-11a The Conducting System of the Heart.Sinoatrial (SA) node Internodal pathways Atrioventricular (AV) node AV bundle Bundle branches Purkinje fibers a Components of the conducting system.

60 20-2 The Conducting SystemThe Sinoatrial (SA) Node In posterior wall of right atrium Contains pacemaker cells Connected to AV node by internodal pathways Begins atrial activation (Step 1)

61 20-2 The Conducting SystemThe Atrioventricular (AV) Node In floor of right atrium Receives impulse from SA node (Step 2) Delays impulse (Step 3) Atrial contraction begins

62 20-2 The Conducting SystemThe AV Bundle In the septum Carries impulse to left and right bundle branches Which conduct to Purkinje fibers (Step 4) And to the moderator band Which conducts to papillary muscles

63 20-2 The Conducting SystemPurkinje Fibers Distribute impulse through ventricles (Step 5) Atrial contraction is completed Ventricular contraction begins

64 20-2 The Conducting SystemAbnormal Pacemaker Function Bradycardia – abnormally slow heart rate Tachycardia – abnormally fast heart rate Ectopic pacemaker Abnormal cells Generate high rate of action potentials Bypass conducting system Disrupt ventricular contractions

65 20-2 The Conducting SystemThe Electrocardiogram (ECG or EKG) A recording of electrical events in the heart Obtained by electrodes at specific body locations Abnormal patterns diagnose damage

66 20-2 The Conducting SystemFeatures of an ECG P wave Atria depolarize QRS complex Ventricles depolarize T wave Ventricles repolarize

67 20-2 The Conducting SystemTime Intervals between ECG Waves P–R interval From start of atrial depolarization To start of QRS complex Q–T interval From ventricular depolarization To ventricular repolarization

68 Figure 20-13a An Electrocardiogram.Electrode placement for recording a standard ECG.

69 Figure 20-13b An Electrocardiogram.800 msec +1 R R P wave (atria depolarize) T wave (ventricles repolarize) S–T segment +0.5 P–R segment Millivolts Q S S–T interval P–R interval Q–T interval QRS interval (ventricles depolarize) −0.5 b An ECG printout is a strip of graph paper containing a record of the electrical events monitored by the electrodes. The placement of electrodes on the body surface affects the size and shape of the waves recorded. The example is a normal ECG; the enlarged section indicates the major components of the ECG and the measurements most often taken during clinical analysis.

70 Figure 20-14 Cardiac Arrhythmias (Part 1 of 2).Premature Atrial Contractions (PACs) Premature atrial contractions (PACs) often occur in healthy individuals. In a PAC, the normal atrial rhythm is momentarily interrupted by a “surprise” atrial contraction. Stress, caffeine, and various drugs may increase the incidence of PACs, presumably by increasing the permeabilities of the SA pacemakers. The impulse spreads along the conduction pathway, and a normal ventricular contraction follows the atrial beat. P P P Paroxysmal Atrial Tachycardia (PAR) In paroxysmal (par-ok-SIZ-mal) atrial tachycardia, or PAT, a premature atrial contraction triggers a flurry of atrial activity. The ventricles are still able to keep pace, and the heart rate jumps to about 180 beats per minute. P P P P P P Atrial Fibrillation (AF) During atrial fibrillation (fib-ri-LĀ-shun), the impulses move over the atrial surface at rates of perhaps 500 beats per minute. The atrial wall quivers instead of producing an organized contraction. The ventricular rate cannot follow the atrial rate and may remain within normal limits. Even though the atria are now nonfunctional, their contribution to ventricular end-diastolic volume (the maximum amount of blood the ventricles can hold at the end of atrial contraction) is so small that the condition may go unnoticed in older individuals.

71 Figure 20-14 Cardiac Arrhythmias (Part 2 of 2).Premature Ventricular Contractions (PVCs) Premature ventricular contractions (PVCs) occur when a Purkinje cell or ventricular myocardial cell depolarizes to threshold and triggers a premature contraction. Single PVCs are common and not dangerous. The cell responsible is called an ectopic pacemaker. The frequency of PVCs can be increased by exposure to epinephrine, to other stimulatory drugs, or to ionic changes that depolarize cardiac muscle plasma membranes. P T P T P T Ventricular Tachycardia (VT) Ventricular tachycardia is defined as four or more PVCs without intervening normal beats. It is also known as VT or V-tach. Multiple PVCs and VT may indicate that serious cardiac problems exist. P Ventricular Fibrillation (VF) Ventricular fibrillation (VF) is responsible for the condition known as cardiac arrest. VF is rapidly fatal, because the ventricles quiver and stop pumping blood.

72 20-3 The Cardiac Cycle The Cardiac CycleIs the period between the start of one heartbeat and the beginning of the next Includes both contraction and relaxation

73 20-3 The Cardiac Cycle Two Phases of the Cardiac CycleWithin any one chamber Systole (contraction) Diastole (relaxation)

74 20-3 The Cardiac Cycle Blood Pressure In any chamberRises during systole Falls during diastole Blood flows from high to low pressure Controlled by timing of contractions Directed by one-way valves

75 20-3 The Cardiac Cycle Cardiac Cycle and Heart RateAt 75 beats per minute (bpm) Cardiac cycle lasts about 800 msec When heart rate increases All phases of cardiac cycle shorten, particularly diastole

76 20-3 The Cardiac Cycle Heart Sounds S1 S2 Loud soundsProduced by AV valves S2 Produced by semilunar valves

77 20-3 The Cardiac Cycle S3, S4 Heart Murmur Soft soundsBlood flow into ventricles and atrial contraction Heart Murmur Sounds produced by regurgitation through valves

78 Figure 20-18a Heart Sounds. Sounds heard Aortic valve Valve location Valve location Pulmonary valve Sounds heard Left AV valve Sounds heard Valve location Right AV valve Valve location Sounds heard a Placements of a stethoscope for listening to the different sounds produced by individual valves

79 20-4 Cardiodynamics CardiodynamicsThe movement and force generated by cardiac contractions End-diastolic volume (EDV) End-systolic volume (ESV) Stroke volume (SV) SV = EDV – ESV Ejection fraction The percentage of EDV represented by SV

80 20-4 Cardiodynamics Cardiac Output (CO)The volume pumped by left ventricle in one minute CO = HR  SV CO = cardiac output (mL/min) HR = heart rate (beats/min) SV = stroke volume (mL/beat)