Principles of Human Anatomy and Physiology, 11e1 Chapter 20 THE CARDIOVASCULAR SYSTEM: THE HEART Lecture Outline

Principles of Human Anatomy and Physiology, 11e2 INTRODUCTION The cardiovascular system consists of the blood, heart, and blood vessels. The heart is the pump that circulates the blood through an estimated 60,000 miles of blood vessels. The study of the heart and diseases associated with it is known as cardiology.

Principles of Human Anatomy and Physiology, 11e3 Location of the heart The heart is situated between the lungs with about two- thirds of its mass to the left of the midline. It is about the size of your closed fist.

Principles of Human Anatomy and Physiology, 11e4 Pericardium The heart is enclosed and held in place by the pericardium, a membrane. –It confines the heart in its position in the chest –It also allows movement during contraction –An inflammation of the pericardium is known as pericarditis. It is caused by a virus and causes pain. Treatment includes draining fluid through a needle.

Principles of Human Anatomy and Physiology, 11e5 Layers of Heart Wall The wall of the heart has 3 layers: Epicardium –Thin, transparent outer layer Myocardium – cardiac muscle layer is the bulk of the heart, it does the pumping Endocardium –Very thin, lines the chambers and vessels

Principles of Human Anatomy and Physiology, 11e6 Chambers and Sulci of the Heart (Figure 20.3). Four chambers –2 upper atria (right and left atrium) –2 lower ventricles (right and left) Sulci - grooves on surface of heart containing coronary blood vessels and fat

Principles of Human Anatomy and Physiology, 11e7 Right Atrium Blood from the body returns to the heart and goes into the right atrium. This is shown as blue because the oxygen has been used up Receives blood from 3 sources –superior vena cava, inferior vena cava and coronary sinus

Principles of Human Anatomy and Physiology, 11e8 Right Ventricle Blood from the right atrium then flows into the right ventricle Blood leaves the right ventricle through pulmonary valves, it then goes into the pulmonary artery to pick up oxygen

Principles of Human Anatomy and Physiology, 11e9 Left Atrium Forms most of the base of the heart Shown as red because it has oxygen Receives blood from lungs through 4 pulmonary veins

Principles of Human Anatomy and Physiology, 11e10 Left Ventricle Forms the apex (bottom) of heart It has oxygenated blood (red) Blood from the left atrium flows through the left ventricle and into the aorta, where it is pumped through the body.

Principles of Human Anatomy and Physiology, 11e11 Myocardial Thickness and Function Thickness of myocardium varies according to the function of the chamber Atria are thin walled, deliver blood to adjacent ventricles Ventricle walls are much thicker and stronger –right ventricle supplies blood to the lungs (little flow resistance) –left ventricle wall is the thickest to supply systemic circulation

Principles of Human Anatomy and Physiology, 11e12 HEART VALVES AND CIRCULATION OF BLOOD Valves open and close in response to pressure changes as the heart contracts and relaxes. –Atrioventricular (A/V) –Semilunar

Principles of Human Anatomy and Physiology, 11e13 A-V valves open and allow blood to flow from atria into ventricles when ventricular pressure is lower than atrial pressure Atrioventricular Valves Open

Principles of Human Anatomy and Physiology, 11e14 A-V valves close preventing backflow of blood into atria Atrioventricular Valves Close

Principles of Human Anatomy and Physiology, 11e15 Semilunar Valves SL valves open with ventricular contraction –allow blood to flow into pulmonary trunk and aorta SL valves close with ventricular relaxation –prevents blood from returning to ventricles, blood fills valve cusps, tightly closing the SL valves

Flow of Blood Oxygen enters the body through the lungs Pulmonary veins carry it to the left atrium (red) It then goes through the left ventricle (red) The aorta pumps it into the body through arteries (red) The body uses up the oxygen (red to blue) Blood returns to the heart through veins (blue) It enters the right atrium (blue) It goes through the right ventricle (blue) Then it goes into pulmonary arteries to get more oxygen from the lungs and the process starts over (blue to red) Principles of Human Anatomy and Physiology, 11e16

Principles of Human Anatomy and Physiology, 11e17 Blood Circulation Blood flow –blue = deoxygenated –red = oxygenated –Heart  arteries  arterioles  capillaries  venules  veins  heart

Project Part 1 Get a poster. Divide it in half. On today’s half, draw and color a picture of the heart. Refer to pages Include the following: Both atria and ventricles Vena cava Aorta Pulmonary arteries Pulmonary veins Principles of Human Anatomy and Physiology, 11e18

Principles of Human Anatomy and Physiology, 11e19 Autorhythmic Cells: The Conduction System Cardiac muscle cells are autorhythmic cells because they are self-excitable. They repeatedly generate spontaneous action potentials that then trigger heart contractions. These cells act as a pacemaker to set the rhythm for the entire heart. They form the conduction system, the route for propagating action potential through the heart muscle.

Principles of Human Anatomy and Physiology, 11e20 Electrocardiogram A recording of the electrical changes that accompany each cardiac cycle (heartbeat) is called an electrocardiogram (ECG or EKG). The ECG helps to determine if the conduction pathway is abnormal, if the heart is enlarged, and if certain regions are damaged.

Principles of Human Anatomy and Physiology, 11e21 THE CARDIAC CYCLE A cardiac cycle consists of the systole (contraction) and diastole (relaxation) of both atria, rapidly followed by the systole and diastole of both ventricles. Pressure and volume changes during the cardiac cycle This is what is measured when blood pressure is taken.

Principles of Human Anatomy and Physiology, 11e22 Auscultation The act of listening to sounds within the body is called auscultation, and it is usually done with a stethoscope. The first heart sound (lubb) is created by blood turbulence associated with the closing of the AV valves. The second heart sound (dupp) represents the closing of the semilunar valves.

Principles of Human Anatomy and Physiology, 11e23 CARDIAC OUTPUT Cardiac output (CO) is the volume of blood ejected from the left ventricle into the aorta each minute. Cardiac reserve is the ratio between the maximum cardiac output a person can achieve and the cardiac output at rest.

Principles of Human Anatomy and Physiology, 11e24 Regulation of Heart Rate Nervous control from the cardiovascular center in the medulla Heart rate is also affected by hormones And by ions (Na +, K +, Ca 2+ ) And by age, gender, diet, physical fitness, and temperature

Principles of Human Anatomy and Physiology, 11e25 Clinical Problems MI = myocardial infarction –death of area of heart muscle from lack of O 2 –replaced with scar tissue –results depend on size & location of damage Blood clot –use clot dissolving drugs streptokinase or t-PA & heparin –balloon angioplasty

Principles of Human Anatomy and Physiology, 11e26 Risk Factors for Heart Disease Risk factors in heart disease: –high blood cholesterol level – high blood pressure – cigarette smoking – obesity & lack of regular exercise. Other factors include: – diabetes – genetic predisposition – male gender – high blood levels of fibrinogen (blood clotting factor) – left ventricular hypertrophy

Principles of Human Anatomy and Physiology, 11e27 Desirable Levels of Blood Cholesterol for Adults TC (total cholesterol) under 200 mg/dl LDL under 130 mg/dl HDL over 40 mg/dl Normally, triglycerides are in the range of mg/dl. Among the therapies used to reduce blood cholesterol level are exercise, diet, and drugs.

Principles of Human Anatomy and Physiology, 11e28 EXERCISE AND THE HEART A person’s cardiovascular fitness can be improved with regular exercise. –Aerobic exercise (any activity that works large body muscles for at least 30 minutes, preferably 3 – 5 times per week) increases cardiac output and elevates metabolic rate. –Regular exercise also decreases anxiety and depression, controls weight, and increases fibrinolytic activity.

Principles of Human Anatomy and Physiology, 11e29 Coronary Artery Disease Heart muscle receiving insufficient blood supply –Caused by narrowing of vessels –Risk factors for development of CAD include high blood cholesterol levels, high blood pressure, cigarette smoking, obesity, diabetes, “type A” personality, and sedentary lifestyle. Treatment –drugs, bypass graft, angioplasty, stent

Principles of Human Anatomy and Physiology, 11e30 Arrythmia Arrhythmia (disrhythmia) is an irregularity in heart rhythm resulting from a defect in the conduction system of the heart.

Principles of Human Anatomy and Physiology, 11e31 Congestive Heart Failure Congestive heart failure is a chronic or acute state that results when the heart is not capable of supplying the oxygen demands of the body. Causes of CHF –coronary artery disease, hypertension,, valve disorders, congenital defects Left side heart failure –less effective pump so more blood remains in ventricle –heart is overstretched & even more blood remains –blood backs up into lungs as pulmonary edema –suffocation & lack of oxygen to the tissues Right side failure –fluid builds up in tissues as peripheral edema

Principles of Human Anatomy and Physiology, 11e32 Murmurs A heart murmur is an abnormal sound that consists of a flow noise that is heard before, between, or after the lubb-dupp or that may mask the normal sounds entirely. Some murmurs are caused by turbulent blood flow around valves due to abnormal anatomy or increased volume of flow. Not all murmurs are abnormal or symptomatic, but most indicate a valve disorder.

Project Part 2 On the other side of your poster, you will describe a cardio vascular disease or disorder. Include the following: Name of disease Type of disease (genetic, dietary etc) Risk Factors Population Affected Signs/Symptoms Treatments Prognosis Disease by Last Name: A  C = Anemia D  Fra = Sickle Cell Fre  La = Leukemia Le  Mi = Coronary Artery Disease Mo  O = Arteriosclerosis P  Ra = Congenital Heart Defects Ri  S = Arrhythmias T  W = Hypertension Principles of Human Anatomy and Physiology, 11e33