MR250 Unit 7 Reading-Chapter 8 Cardiology and Hematology
The cardiovascular or circulatory system consists of the heart and the blood vessels (arteries, capillaries, veins) (see Figures 8-1 and 8-2). The purpose of the system is to provide rapid delivery to the tissues of oxygen from the lungs; nutrients, minerals, vitamins, and water from the digestive system; hormones from glands; and white blood cells from bone marrow and lymphoid tissue, while removing waste products and delivering them to the lungs (carbon dioxide), liver (broken-down red blood cells), and kidney (surplus water, nitrogenous wastes) for excretion.
Anatomy in Brief
The heart is a pump—actually two synchronized pumps, each handling a different segment of the circulating blood at any given moment. The right atrium(antechamber) and the right ventricle receive venous blood from the systemic circulation and pump it into the lungs for gas exchange. The left atrium andleft ventricle receive freshly oxygenated blood from the lungs and pump it through the arteries into the systemic circulation.
The contraction of a heart chamber is called systole; relaxation and refilling is called diastole. Valves in the heart (one for each of the four chambers) prevent back-flow of blood from a chamber during systole. The heart is encased in a protective sac called the pericardium.
The names of the coronary arteries and branches are frequently mentioned in angiographic and surgical reports. The major vessels are the left main coronary artery, the left anterior descending (LAD) coronary artery, the right coronary artery (RCA), and the circumflex coronary artery. Names of branches of these take on additional terms, such as the left anterior descending diagonal (LADD). Other vessels to remember are the circumflex marginal, distal branches, and the posterior descendings. The major conduits are the aorta and pulmonary artery. The valves are aortic, mitral, pulmonary, and tricuspid.
Terminology Review anemia Deficiency of red blood cells. arrhythmia Irregular rhythm of the heartbeat, with or without an abnormally slow or fast rate. ascites Swelling of the abdomen due to effusion of fluid into the peritoneal cavity. auscultation of the heart The physician notes the quality and loudness of heart sounds heard through a stethoscope at the four valve areas. bradyarrhythmia A pulse that is both irregular and abnormally slow. bradycardia Abnormal slowness of the heartbeat (pulse less than 60/min). bruit A rough vascular sound, synchronous with the heartbeat, heard on auscultation over a narrowing in an artery. cardiomegaly Enlargement of the heart. clubbing Club-shaped deformity of fingertips, seen in chronic pulmonary disease. cor pulmonale Dilatation, hypertrophy, or failure of the right ventricle due to acute or chronic pulmonary disease. crepitant rale A fine crackling rale. dependent edema Edema of the lower extremities, aggravated by the dependent (downward hanging) position. diaphoresis Sweating. dyspnea Shortness of breath. edema Swelling due to the presence of fluid in tissue spaces. effusion An abnormal accumulation of fluid in a body cavity, such as the pericardium. ejection fraction (EF) The percentage of the blood contained in a ventricle at the end of diastole that is ejected from the heart during the succeeding systole, normally 65% or higher. embolism Obstruction of a blood vessel by a detached blood clot, air, fat, or injected material. exudate A material deposited in or on tissues as a result of inflammation or degeneration and consisting of protein-rich fluid, inflammatory cells, and tissue debris. fibrillation Rapid, random, ineffectual twitching of cardiac muscle, instead of normal regular systolic contractions, due usually to metabolic or coronary vascular disease. Whereas atrial fibrillation can continue for years without serious impairment of health, ventricular fibrillation is rapidly fatal. gallop rhythm A cardiac rhythm that simulates the sound of a galloping
