Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Memmler’s The Human Body in Health and Disease 11 th edition Chapter 14 The Heart and Heart Disease

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Circulation and the Heart Circulation Continuous one-way circuit of the blood vessels Propelled by heart

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Location of the Heart Between the lungs Left of the midline of the body In mediastinum Apex pointed toward left

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Structure of the Heart Three tissue layers Endocardium lines heart’s interior Myocardium is thickest layer; the heart muscle Epicardium is thin outermost layer

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Pericardium The sac that encloses the heart Fibrous pericardium holds heart in place Serous membrane –Parietal layer –Pericardial cavity –Visceral layer (epicardium)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Layers of the heart wall and pericardium. The serous pericardium covers the heart and lines the fibrous pericardium. ZOOMING IN Which layer of the heart wall is the thickest?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: Which layer of the heart is the heart muscle? a. epicardium b. myocardium c. pericardium

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: b. myocardium

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Special Features of the Myocardium Cardiac muscles Are lightly striated (striped) Have single nucleus cells Are controlled involuntarily Have intercalated disks Have branching muscle fibers

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Divisions of the Heart Double pump Right side pumps blood low in oxygen to the lungs –Pulmonary circuit Left side pumps oxygenated blood to remainder of body –Systemic circuit

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Four Chambers Right atrium –Receives low-oxygen blood returning from body tissue through superior vena cava and inferior vena cava Left atrium –Receives high-oxygen blood from lungs Right ventricle –Pumps blood from right atrium to lungs Left ventricle –Pumps oxygenated blood to body

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The heart as a double pump. The right side of the heart pumps blood through the pulmonary circuit to the lungs to be oxygenated; the left side of the heart pumps blood through the systemic circuit to all other parts of the body. ZOOMING IN What vessel carries blood into the systemic circuit?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The heart and great vessels. ZOOMING IN Which heart chamber has the thickest wall?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: Which chamber of the heart receives oxygenated blood coming in from the lungs in the pulmonary veins? a. right atrium b. left ventricle c. left atrium

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: c.left atrium (upper left chamber) Answer: c. left atrium (upper left chamber)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Four Valves Atrioventricular valves –Entrance valves –Right atrioventricular (AV) valve (tricuspid valve) –Left atrioventricular (AV) valve (bicuspid valve) Semilunar valves –Exit valves –Pulmonary valve –Aortic valve

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Valves of the heart (superior view from anterior, atria removed). (A) When the heart is relaxed (diastole), the AV valves are open and blood flows freely from the atria to the ventricles. The pulmonary and aortic valves are closed. (B) When the ventricles contract, the AV valves close and blood pumped out of the ventricles opens the pulmonary and aortic valves. ZOOMING IN How many cusps does the right AV valve have? The left?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Pathway of blood through the heart. Blood from the systemic circuit enters the right atrium (1) through the superior and inferior venae cavae, flows through the right AV (tricuspid) valve (2), and enters the right ventricle (3). The right ventricle pumps the blood through the pulmonary (semilunar) valve (4) into the pulmonary trunk, which divides to carry blood to the lungs in the pulmonary circuit. Blood returns from the lungs in the pulmonary veins, enters the left atrium (5), and flows through the left AV (mitral) valve (6) into the left ventricle (7). The left ventricle pumps the blood through the aortic (semilunar) valve (8) into the aorta, which carries blood into the systemic circuit.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Supply to the Myocardium Coronary circulation Right coronary artery Left coronary artery Coronary sinus

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood vessels that supply the myocardium. Coronary arteries and cardiac veins are shown. (A) Anterior view. (B) Posterior view.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Opening of coronary arteries in the aortic valve (anterior view). (A) When the left ventricle contracts, the aortic valve opens. The valve cusps prevent filling of the coronary arteries. (B) When the left ventricle relaxes, backflow of blood closes the aortic valve and the coronary arteries fill.

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Function of the Heart Left and right sides of heart work together in cardiac cycle (heartbeat) Systole (active phase, contraction) Diastole (resting phase)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The cardiac cycle. ZOOMING IN When the ventricles contract, what valves close? What valves open?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Output Calculating cardiac output Cardiac output (CO) Stroke volume (SV) Heart rate (HR) CO = HR 3 SV

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Heart’s Conduction System Electrical energy stimulates heart muscle Nodes –Sinoatrial (SA) node (pacemaker) –Atrioventricular (AV) node Specialized fibers –Atrioventricular bundle (bundle of His) –Purkinje fibers (conduction myofibers) Intercalated disks

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Conduction system of the heart. The sinoatrial (SA) node, the atrioventricular (AV) node, and specialized fibers conduct the electrical energy that stimulates the heart muscle to contract. ZOOMING IN What parts of the conduction system do the internodal pathways connect?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Conduction Pathway Sinus rhythm Sinoatrial (SA) node Atria Atrioventricular (AV) node Internodal pathways Bundle of His Bundle branches and Purkinje fibers Ventricles

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Control of the Heart Rate Influences that allow heart to meet changing needs rapidly Autonomic nervous system (ANS) Sympathetic nervous system Parasympathetic system –Cranial nerve X

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Variations in Heart Rates Bradycardia Tachycardia Sinus arrhythmia Premature beat (extrasystole)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Sounds Lub Dup Murmurs –Organic –Functional

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: What is the medical term for a heart rate of more than 100 beats/min? a. bradycardia b. hypercardia c. tachycardia

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: c. tachycardia

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Disease Most common cause of death in industrialized countries is heart and circulatory system disease

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Classifications of Heart Disease Anatomical classification –Endocarditis –Myocarditis –Pericarditis Causative factors classification –Congenital heart disease –Rheumatic heart disease –Coronary artery disease –Heart failure

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Congenital Heart Disease Congenital heart disease often results from fetal development defects Atrial septal defect Patent (open) ductus arteriosus Ventricular septal defect Coarctation of the aorta Tetralogy of Fallot

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Rheumatic Heart Disease Streptococci release toxins during infection Antibodies that combat toxin also attack heart valves Heart valves become inflamed Valve cusps thicken and harden Pulmonary congestion occurs

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Coronary Artery Disease Coronary arteries can degenerate Myocardial infarction –Creatine kinase released upon any muscle damage. Tests for certain forms of CK indicate whether an MI occurred. Angina pectoris Abnormalities of heart rhythm Treatment of heart attacks

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: What is the name of the fatty substance that builds up inside the vessel walls in atherosclerosis? a. plaque b. lumen c. thrombus

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: a. plaque

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Failure Heart is unable to pump sufficient blood Heart chambers enlarge Blood backs up into lungs Ventricular muscles have decreased ability Fluid accumulates in lungs, liver, abdomen, legs

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Heart in the Elderly How the heart can age Heart shrinks Decreased contraction strength Valves become less flexible Murmur develops Cardiac output decreases Abnormal rhythms Heart block

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Prevention of Heart Disease Risk factors that cannot be modified –Age –Gender –Heredity –Body type Risk factors that can be modified –Smoking –Physical inactivity –Weight –Diet –Blood pressure –Diabetes, gout

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Studies Stethoscope Electrocardiograph (ECG or EKG) –Electrodes Catheterization –Fluoroscope Echocardiography (ultrasound cardiography) –Oscilloscope

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Treatment of Heart Disease Medical approaches Surgical approaches Combined approaches

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Medications Digitalis Nitroglycerin Beta-adrenergic blocking agents (beta-blockers) Antiarrhythmic agents Slow calcium-channel blockers Anticoagulants –Aspirin

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Correction of Arrhythmias Artificial pacemaker –Set rate –Only when heart skips beat –Adjustable pacing rate Implantable cardioverter-defibrillator (ICD)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heart Surgery Coronary artery bypass graft (CSBG) Angioplasty Valve replacement Surgical transplantation of heart or heart and lungs Artificial heart

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: The technique to restore normal heartbeat by either electric shock or drugs is known as: a. defibrillation b. cardioversion c. ablation

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: b. cardioversion