The Cardiovascular System Mrs. Jessica Dean, RN, BSN

The Cardiovascular System: Heart Anatomy Introduction/Overview Daily Objectives: Describe the location of the heart and trace its outline on the surface of the chest. Discuss the external and internal anatomy of the chambers of the heart. Describe the structure and function of the valves of the heart.

I. Heart Anatomy: Location/Size The heart is about the size of your cupped hands. It is hollow, cone-shaped, and weighs less than 1 pound The heart rests on the diaphragm, near the midline of the thoracic cavity in the mediastinum and is flanked on each side by the lungs. About two-thirds of the mass of the heart lies to the left of the body’s midline.

The pointed end of the heart is the apex and is directed towards the left hip. The wider end is called the base and it points towards the right shoulder and lies beneath the 2nd rib. Heart Anatomy : Coverings / Wall - The membrane that surrounds and protects the heart is the pericardium. It confines the heart to its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction.

The heart wall consists of three layers: the pericardium, the myocardium, and the endocardium. Pericardium(external layer) = also called the visceral layer, is the thin, transparent outer layer of the wall. Myocardium (middle layer) = cardiac muscle tissue, makes up the bulk of the heart and is responsible for its pumping action. Endocardium (inner layer) = is a thin layer of endothelium overlying a thin layer of connective tissue . It provides a smooth lining for the chamber of the heart and covers the valves of the heart.

Heart Anatomy: Chambers of the Heart The heart contains four chambers. The two uppers chambers are the atria and the two lower chambers are the ventricles. The right atrium forms the right border of the heart.

The right atrium receives blood from three veins: superior vena cava, inferior vena cava, and coronary sinus. Between the right atrium and left atrium is a thin partition called the interatrial septum. A prominent feature of this septum is an oval depression called the fossa ovalis, which is an opening in the interatrial septum of the fetal heart that normally closes soon after birth.

- Blood passes from the right atrium into the right ventricle through a valve called the tricuspid valve (contains three cusps).

The right ventricle forms most of the anterior surface of the heart. The right ventricle is separated from the left ventricle by a partition called the interventricular septum. Left atrium forms most of the base of the heart. It receives blood from the lungs through four pulmonary veins.

- Blood passes from the left atrium into the left ventricle through the bicuspid (mitral) valve (has two cusps). The left ventricle forms the apex of the heart. Blood passes from the left ventricle into the largest artery of the body, the ascending aorta through the aortic valve.

The Cardiovascular System: Blood Vessels Daily Objectives: Contrast the structure and function of arteries, arterioles, capillaries, venules, and veins. Discuss blood formation and function.

II. Composition and Functions of Blood: Recall blood is the only fluid connective tissue that constitutes the transport medium of the circulatory system. Blood has three functions: Transports nutrients, dissolved (oxygen and carbon dioxide), enzymes, hormones, and waste materials. Regulate body temperature, fluids, pH, and electrolytes. Defend the body against disease.

Approximately 55 % of blood is made up of a fluid portion called plasma. Plasma is a straw-colored liquid and is 90% water and 10% dissolved fats, salts, sugars, and proteins. Red blood cells (Erythrocytes) = RBCs are the most numerous of the blood cells and account for about 45% of total volume. Approx. 5 million per mm3 of blood. RBCs are biconcave (narrower at the center than along the edges). White blood cells (Leukocytes) = outnumbered by RBCs almost 1000 to 1. Approx. 4,000-10,000 per mm3 of blood and less than 1% of volume.

WBCs are produced in bone red marrow, lymph nodes, and spleen. The main function of WBCs is to protect the body against invasion by foreign cells, viruses, parasites, and tumor cells.

III. Blood Vessels: Blood vessels form a closed system of tubes that carries blood away from the heart, transports it to the tissue of the body, and then returns it to the heart. Arteries are vessels that carry blood AWAY from the heart to the tissues. Large, elastic arteries leave the heart and divide into medium-sized, muscular arteries that branch out into the various regions of the body. Medium- sized arteries then divide into smaller arteries called arterioles. As arterioles enter a tissue, they branch into countless microscopic vessels called capillaries.

Substances are exchanged between the blood and body tissues through the thin walls of the capillaries. Before leaving the tissue, groups of capillaries unite to form small veins called venules, which merge to form progressively larger blood vessels called veins. Veins then convey blood from the tissues back to the heart.

The Cardiovascular System: Daily Objectives: Describe the flow of blood through the chambers of the heart and through the systemic and pulmonary circulations. Describe the phases, timing, and heart sounds associated with a cardiac cycle

Blood Circulation: -With each beat, the heart pumps blood into two closed circuits- the systemic circulation and the pulmonary circulation. -The left side of the heart is the pump for the systemic circulation; it receives freshly oxygenated blood from the lungs. -The left ventricle ejects blood into the aorta. From the aorta, the blood divides into smaller systemic arteries that carry blood to all the organs throughout the body (except the air sacs in the lungs).

- Exchange of nutrients and gases occurs across the thin capillary walls: Blood unloads oxygen and picks up carbon dioxide. Venules carry deoxygenated blood away from tissues and merge to form larger systemic veins, and ultimately the blood flows back to the right atrium. -The right side of the heart is the pump for the pulmonary circulation; it receives all the deoxygenated blood returning from the systemic circulation. -Blood ejected from the right ventricle flows into the pulmonary trunk, which branches into pulmonary arteries that carry blood to the right and left lungs. -Blood then unloads carbon dioxide, which is exhaled, and picks up oxygen.

- The freshly oxygenated blood then flows into pulmonary veins and returns to the left atrium. Cardiac Cycles: A single cardiac cycle includes all the events associated with one heartbeat. In each cardiac cycle, the atria and ventricles alternately contract and relax, forcing blood from areas of higher pressure to areas of lower pressure. Systole = phase of contraction Diastole = phase of relaxation

Heart Sounds: The act of listening to sounds within the body is called auscultation, and it is usually done with a stethoscope. The sound of the heartbeat comes primarily from blood turbulence caused by the closing of the heart valves. During each cardiac cycle, four heart sounds are generated, but in a normal heart only the first and second heart sounds are loud enough to be heard by listening through a stethoscope.

Heart sounds provide valuable information about the mechanical operation of the heart. A heart murmur is an abnormal sound consisting of a rushing or gurgling noise that is heard before, between, or after the normal heart sounds, or that may mask the normal heart sounds. Although some heart murmurs are “innocent,” meaning they are not associated with a significant heart problem, most often a murmur indicates a valve disorder.

The Cardiovascular System: Daily Objectives: Discuss various dysfunctions / disorders of the Cardiovascular System. Identify some common methods of assessing the heart.

V. Cardiovascular System Dysfunctions / Disorders Hypertension = persistently high blood pressure, is defined as systolic pressure of 140mm Hg or greater and diastolic blood pressure of 90 mm Hg or greater. Recall that a blood pressure of 120/80 is normal and desirable in a healthy adult. (Although, the American Heart Association now suggest: Systolic less than 130 and Diastolic less than 70). Hypertension is the most common disorder affecting the heart and blood vessels; it is a major cause of heart failure, kidney disease, and stroke. 90-95% of all cases of hypertension are classified as primary hypertension, which is a persistently elevated blood pressure that cannot be attributed to any cause.

Lifestyle Changes to Reduce Hypertension: 1. Lose weight 2. Limit alcohol intake 3. Exercise 4. Reduce intake of sodium 5. Don’t smoke 6. Manage stress 7. Maintain dietary intake of potassium, calcium, and magnesium.

Pulse Rates: Tachycardia: An abnormally rapid resting heartbeat or pulse rate over (100/min). Bradycardia: A slow resting heart rate or pulse rate under (60/min). Normal sitting pulse rate is between 70-80

-Heart Attack: A blockage in the heart's arteries may reduce or completely cut off the blood supply to a portion of the heart. -This can cause a blood clot to form and totally stop blood flow in a coronary artery, resulting in a heart attack (also called an acute myocardial infarction or MI). -Irreversible injury to the heart muscle usually occurs if medical help is not received promptly. Unfortunately, it is common for people to dismiss heart attack symptoms.

Symptoms of a Heart Attack Uncomfortable pressure, fullness, squeezing or pain in the center of the chest lasting more than a few minutes. Pain spreading to the shoulders, neck or arms. The pain may be mild to intense. It may feel like pressure, tightness, burning, or heavy weight. It may be located in the chest, upper abdomen, neck, jaw, or inside the arms or shoulders. Chest discomfort with lightheadedness, fainting, sweating, nausea or shortness of breath. Anxiety, nervousness and/or cold, sweaty skin. Paleness or pallor. Increased or irregular heart rate. Feeling of impending doom.

Heart Attack Statistics: -1.5 million heart attacks occur in the United States each year with 500,000 deaths. -More than 233,000 women die annually from cardiovascular disease. -A heart attack occurs about every 20 seconds with a heart attack death about every minute. -Sudden death is more common among women with heart attack. -Almost 14 million Americans have a history of heart attack or angina.

-Only 31% of women know that cardiovascular disease is the leading cause of death in the USA. -On the average, women take 2-4 hours longer than men to respond to symptoms of heart attack, limiting the beneficial use of some newer treatments like clot busters that work best within the first hour after onset of pain or discomfort. -Chewing an uncoated aspirin right away, at the first sign of chest discomfort or distress, can reduce the amount of damage to the heart muscle during a heart attack.

-Studies show the most common time for a heart attack to occur is Monday morning. Saturday morning ranks second. Another common time is during the early morning hours, when blood platelets are stickier. -About 50% of deaths occur within one hour of the heart attack ––outside a hospital.

Congestive Heart Failure (CHF) Heart muscles do not beat adequately to supply blood needs of the body May involve either right or left side of heart Symptoms: edema, dyspnea, cyanosis, weak and rapid pulse Treatment: diuretics, elastic support hose to improve circulation, oxygen therapy, low sodium diet

Arteriosclerosis Hardening or thickening of walls of arteries Causes loss of elasticity and contractility Commonly occurs as result of aging Causes hypertension and can lead to aneurysm or cerebral hemorrhage

Atherosclerosis Fatty plaques, frequently cholesterol, deposited on walls of arteries Causes narrowing of opening, which reduces or eliminates the flow of blood If plaques break loose, they can circulate through the blood stream as emboli Treatment: low-cholesterol diet, exercise

Aneurysm Ballooning out or saclike formation on wall of artery Causes: disease, congenital defects, injuries leading to a weakening of structure of wall of artery Symptoms: some cause pain and pressure and some have none Common sites are cerebral, aortal, and abdominal If ruptures, hemorrhage occurs, can cause death Treatment: surgical removal and replacement with a graft or another blood vessel

Embolus Foreign substance circulating in blood stream Can be air, blood clot, bacterial clumps, fat globule Blockage of vessel occurs when embolus enters an artery or capillary too small for passage

Phlebitis Inflammation of vein, frequently in leg Symptoms: pain, edema, redness, discoloration at site Treatment Anticoagulants and pain med Elevate affected area Support hose Surgery to remove clot

Varicose Veins Dilated, swollen vein that have lost elasticity and cause a stasis or decrease blood flow Frequently occur in legs Result from pregnancy, prolonged sitting or standing, and hereditary factors Treatment: exercise, support hose, eliminating tight-fitting or restrictive clothing, surgery to remove vein

Anemia Inadequate # of erythrocytes, hemoglobin or both Symptoms: pallor, fatigue, dyspnea, rapid heart rate Acute blood loss anemia Iron deficiency anemia Aplastic anemia Pernicious anemia Sickle cell anemia

Acute blood loss anemia Caused by hemorrhage or rapid blood loss Corrected by blood transfusion

Iron deficiency anemia Caused by inadequate amount of iron to form hemoglobin in erythrocytes Treatment: iron supplements and increased iron intake from green leafy vegetables

Aplastic anemia Caused by injury or destruction of bone marrow Results in poor or no formation of erythrocytes Fatal unless damage can be reversed

Pernicious anemia Caused by lack of intrinsic factor which results in poor absorption of vitamin B12 Results in formation of inadequate and abnormally large erythrocytes Treatment: replacing intrinsic factor and administering B12 injections

Sickle Cell Anemia Chronic inherited anemia Production of abnormal crescent-shaped erythrocytes that carry less oxygen, break easily, and block blood vessels Occurs almost exclusively among African Americans Treatment: transfusions of packed cells and supportive therapy during a crisis

Leukemia Malignant disease of bone marrow or lymph tissue Results in large # of immature WBC Different types—some acute, some chronic Symptoms: fever, pallor, swelling of lymph tissue, fatigue, anemia, joint pain, excessive bruising Treatment Varies, can be chemo, radiation and bone marrow transplant

Hemophilia Inherited disease Occurs almost exclusively in males but carried by females Blood not able to clot due to lack of plasma protein (prolonged or internal bleeding) Treatment: transfusions, administration of missing protein factor

Heart Studies Stethoscope ECG/EKG Catheterization Fluoroscope Ultrasound Echocardiography

Treatments of Heart Disease Artificial pacemakers Heart surgery Coronary bypass surgery Angioplasty Valve replacement Surgical transplantation