© 2009 Delmar, Cengage Learning

Chapter 13

Heart

© 2009 Delmar, Cengage Learning

Functions of theCirculatory System

• Heart is the pump that circulates blood

• Arteries, veins, and capillaries transport the blood

• Blood carries oxygen and nutrients to the cells and carries the waste products away

• Lymph system functions

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Major Blood Circuits

• Blood leaves the heart through arteries and returns by veins

• Blood circulation routes– General or system circulation

– Cardiopulmonary circulation

• Changes in the composition of circulating blood

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The Heart

• About the size of a closed fist

• Weighs about 1 pound

• Located in thoracic cavity; apex of heart lies on the diaphragm and points to the left of the body

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The Heart

• After 4 to 5 minutes without blood flow, the

brain cells are irreversibly damaged

• Can hear the heartbeat through the stethoscope

• Cardiac arrest

• Cardiopulmonary resuscitation (CPR)

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Structure of the Heart

• Hollow, muscular, double pump

• Pericardium and pericardial fluid

• Myocardium– Cardiac muscle tissue

• Endocardium

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Structure of the Heart

• Superior and inferior vena cava

• Coronary sinus

• Pulmonary artery

• Pulmonary veins

• Aorta

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Chambers and Valves

• Separated into right and left halves by septum; then each half separated into an upper and lower chamber

• Upper chambers– Left and right atria

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Chambers and Valves

• Low chambers– Left and right ventricles

• Valves keep blood flow going in one direction

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Valves

• Atrioventricular valves– Tricuspid valve

– Bicuspid or mitral valve

• Semilunar valves– Pulmonary semilunar valve

– Aortic semilunar valve

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Physiology of the Heart

• Double pump

• Right heart– Deoxygenated blood

• Left heart– Oxygenated blood

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Heart Rate and Cardiac Output

• Normal adult rate is between 72 and 80 beats per minute

• Stroke volume

• Calculating the cardiac output

• Exercise increases cardiac output

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Heart Sounds

• Valves make a sound when they close

• Called lubb dupp sounds

• Lubb– Tricuspid and bicuspid valves (S1)

• Dupp– Aortic and pulmonary valves (S2)

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Conduction System

• Electrical impulses cause rhythmic beating of heart

• Sinoatrial (SA) node or pacemaker

• Atrioventricular (AV) node

• Bundle of His

• Purkinje fibers

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ECG or EKG

• The electrocardiogram is a device to record the electrical activity of the heart

• Systole– Contraction

• Diastole– Relaxation

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ECG or EKG

• Positive and negative deflection

• P, QRS, and T waves

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Prevention of Heart Disease

• Heart disease is the leading cause of death– Coronary heart disease

• Risk factors

• Steps to lower risk or prevent heart disease

• Blood cholesterol levels and triglycerides

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Diagnostic Tests Noninvasive

• Angiography

• Cardiac MRI

• Coronary calcium scoring/heart scan

• Echocardiography

• Electrocardiogram

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Diagnostic Tests Noninvasive

• Exercise stress tests

• Holter monitor

• MUGA

• Transesophageal echocardiography

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Diagnostic Tests Invasive

• Cardiac catheterization

• IVUS (intravascular coronary ultrasound)

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Diagnostic Tests Blood Tests

• Arterial blood gases

• BNP

• Lipid panel

• Cardiac enzymes

• INR/Prothrombin time tests

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Animation – The Heart

Click Here to play

Heart animation

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Effects of Aging

• Heart muscle fibers replaced by fibrous tissue

• Heart valves increase in thickness

• Cardiac output decreases

• Changes become more significant when elderly person becomes physically or mentally stressed

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Diseases of the Heart –Common Symptoms

• Arrhythmia

• Bradycardia

• Tachycardia

• Murmurs

• Mitral valve prolapse

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Diseases of the Coronary Artery

• Coronary artery disease (CAD)

• Angina pectoris

• Myocardial infarction

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Infectious Diseases of the Heart

• Pericarditis

• Myocarditis

• Endocarditis

• Rheumatic heart disease

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Heart Failure

• When the ventricles of the heart are unable to contract effectively and blood pools in the heart

• Symptoms depend on which ventricle fails

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Heart Failure

• Left ventricle failure– Dyspnea

• Right ventricle failure– Engorgement of organs, edema and ascites

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Congestive Heart Failure

• Similar to heart failure plus edema of the lower extremities and blood backs up into the lungs

• Treatment

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Rhythm/Conduction Defects

• Heart block– First-degree block

– Second-degree block

– Third-degree block or complete heart block

• Premature contractions– PACs

– PVCs

• Fibrillation

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Types of Heart Surgery

• Angioplasty

• Coronary bypass

• Cardiac stents

• Transmyocardial laser revascularization

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Heart Transplants

• Used as last resort

• Histocompatibility

• Organ rejection

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Medical Highlights

• Pacemaker

• Cardiac resynchronization therapy

• Defibrillator

• Heart pumps