Clinical Anatomy of Human Organism - Essay Example

The human body is composed of billions of cells, each with a distinct function. Despite this diversity in cell function, all cells share certain common elements and functions (Berne & Levy). All cells rely on key elements such as fuel, in the form of food, water and oxygen from the environment in order for the body to survive. The body can only survive for (duration) without oxygen, (compare to food & water). This shows how vital oxygen is to the body. Oxygen delivery to the various parts of body is the primary responsibility of the cardiovascular and respiratory systems. These two systems work in coordination and rely heavily on each other. This booklet will show the basic structure and functions of the organs involved in the cardiovascular and respiratory systems, of great importance, the connection between the heart and the lungs. The two common malfunctions affecting the cardiorespiratory systems, coronary artery disease and asthma, will also be discussed. the heart (Ganong). The heart is a pyramid-shaped, hollow, muscular organ, and said to be the size of a person's fist. It lies in middle of the thorax, in between the two lungs. The walls of the heart are composed of cardiac muscle, the "myocardium", covered externally by the "epicardium" and lined internally with "endocardium". The heart has is divided into four chambers, the two upper chambers are called "atria" (sing. "atrium") and the two lower chambers are called ventricles. The atria are the ensuring a one-way conduit of blood through the chambers and to the pulmonary and systemic circulation. There are four valves: two semilunar valves (aortic and pulmonary valves) and two atrioventricular valves (tricuspid and mitral valves). All of these valves have 3 cusps except the mitral valve which has two cusps. Guarding the right atrioventricular orifice (opening between right atrium and right ventricle) is the tricuspid valve. Eighty percent of blood from the right atrium goes to the right ventricle passively and the remaining twenty percent is pumped via atrial contraction. The right ventricle then pumps the blood to the lungs via the pulmonary artery. Between these two lies the pulmonary valve. Upon oxygenation of blood in the lungs, blood then enters the left atrium via the pulmonary veins. From the left atrium, blood goes to the left ventricle and guarding the left atrioventricular orifice is the mitral valve. The left ventricle then pumps the blood to the systemic circulation via the aorta which is guarded by the aortic valve. The heart's own blood supply is through its right and left coronary arteries, which arise from the ascending aorta immediately above the aortic valve (Snell). Like any other artery, the coronary arteries are also composed of 3 layers: tunica, from the outermost to the innermost: tunica externa, tunica media and tunica intima. It has a thicker tunica media, compared to that of a vein. about by the process known as atherosclerosis.Atherosclerosis doesn't happen abruptly, rather typically occurs over a period of many years, usually many decades. The initiation of this process occurs with the endothelial damage, especially in hypertensive patients. The high-velocity blood creates a high force for the particles in the blood to be turbulent and cause an injury to the endothelium and thus, initiates the inflammatory process. Because of the damage to the endothelium, fats, cholesterol, platelets, cellular waste products, calcium and other substances are deposited in the artery wall. These may stimulate artery wall cells to produce other substances that result in further buildup of cells (Americanheart.org). heart tissue, when this happens, the heart cannot contract optimally. A person may feel chest pains and more often, may lead to myocardial infarction, commonly known as a "heart attack". Nearly all deaths from coronary artery disease are because of a heart attack (British Heart Foundation). It is therefore important to know the "tell-tale" signs of a person having a heart attack and how to administer first-aid. The risk for developing CAD is increased when a person is overweight or obese, a smoker, an alcoholic drinker, lives a sedentary (without regular physical activity) and stressful lifestyle, and has a diet rich in fatty foods (high in fat & cholesterol). The risk is also increased in persons with diabetes and high blood pressure. To prevent heart attacks, a screening using laboratory exams is useful in order to diagnose CAD early in the disease process. The walls of the coronary arteries may be examined by doing a coronary angiogram whereas an electrocardiogram may show ischemic areas in the heart. A magnetic image resonace (MRI) provides a more detailed and accurate diagram of the heart and coronary arteries. Medications such as a low-dose aspirin to prevent blood clots in the artery walls and beta-blockers to lower blood pressure are given to many of the patients. Only in severe cases where the artery is almost completely blocked is surgery required. As mentioned earlier, the respiratory system works in coordination with the cardiovascular system in order to deliver oxygen to the rest of the body. At rest, a normal human breathes 12-15 times per minute. The respiratory system may be divided into conducting and respiratory zones. The nose, pharynx, trachea, primary bronchi up to the first 16 generations of the bronchi are considered the conducting zone, responsible for filtering and warming the air and conducting it to and from the exterior. The respiratory zone is considered from the respiratory bronchiole up to the alveolar sacs. The lungs are soft, spongy and highly elastic conical shaped organs that lie on both sides of the heart in the thorax. The air that enters the body through respiration goes to the lungs via the trachea and enters the left and right primary bronchi. The bronchi divides repeatedly, the smallest of which are less than 1 mm in diameter, called bronchioles. The terminal bronchioles gives rise to the respiratory bronchioles, which end by branching into alveolar ducts that lead into tubular passages with numerous thin-walled outpouchings called alveolar sacs (Snell). The alveoli are lined by two types of epithelial cells: Type I and Type II cells. Type I cells are flat cells and are the primary lining cells and Type II cells are thicker and larger which secrete surfactant. It is here in the alveolar sacs where gas exchange occurs between the air in the alveoli and blood from the capillaries due to its extensive blood supply. Gas exchange occurs passively via diffusion. References BERNE, R. M., KOEPPEN, B. M., & STANTON, B., A. (2008). Berne & Levy physiology. Philadelphia, Mosby/Elsevier. FAUCI, A. S., & HARRISON, T. R. (2008). Harrison's Principles of internal medicine, 17th edition. New York, McGraw-Hill, Medical Pub. Division. GANONG, W. F. (2003). Review of medical physiology. New York, McGraw-Hill. SNELL, R. S. (2003). Clinical anatomy. Philadelphia, Pa, Lippincott Williams & Wilkins. Read More