Senin, 06 Desember 2010



Ari Titin Mulyaningsih, 2010
(English in nursing-midwifery science and technology, Nursalam)

The function of cardiovascular system is to ensure an adequate circulation of blood to the tissue of the body at all times and thus to transport substance to and from the individual cells as required. The main role of the cardiovascular system being a general transport and can be subdivided into the following :
1. Delivery of substance to a body tissues to maintain nutrition and metabolic function. The are oxygen, nutrient, and other substance manufactured in the body such as hormones, amino acids, and defend cells.
2. Removal of carbon dioxides and metabolic end product from tissues and delivery to the appropriate organ for break down and elimination, such us to the lungs, or kidneys.
3. The dissipation of heart away from active tissue and its redistribution around body to maintain body normal temperature.
To the their job, the cardiovascular system consist the heart and it vessels which each of its part has it own function to support an adequate of cardiovascular system.


The heart is a hollow, cone shaped, muscular organ about the size of closed fist. Contracts about 2,5 billions time and pumps about 50 million gallons of blood in an average life time. The bottom part, called the apex, tilts forward and down towards the body left side and rest on the diaphragm. The top part of the heart, called the base, lies just bellow the second rib. Because of the hearth angled position, about 2/3 of the organ lies to the left of midline, and 1/3 to the right.

Three major tissues layers make up the heart wall. The endocardium, myocardium, and epicardium. The endocardium consist of a thin inner layers of endotalium that lines the heart valves and chambers. The myocardium, the middle and the thickest layer of the heart wall, is the muscle that contracts with its hearts beck. The epicardium, the outer most layers of the heart wall, forms the inner layer of the pericardium a fluid filled sac that covers the hearts entire outer surface and protect the heart chambers form friction.

The interior of the heart is divided into four hollow chambers which receive the circulation blood. The two upper chambers are called the right and left atrium, and they are separated by interatria septum. The two lowers chambers are called the right and left ventricle, and these are separated by the interventricular septum. Each atrium is separated from each respective ventricles by a valve. Therefore, it is the septa and the valve which divided the heart into four chambers.

The valves that lie between the atria and their ventricles called the atrioventricular valve (AV). The AV valve between the right atrium and the right ventricle is called the tricuspid valves, because it consist of three cusps or flasps. The AV valve between the left atrium and the left ventricle is called the mitral or bicuspid valves because it has two cusps. When the ventricle contract, the pressure exerted on these valve by the blood force them to close, thus preventing back flow of blood in to the atria. The valve that lie between the ventricle and the major arteries that leave the heart are called the semilunar valves. There are the pulmonic and aortic, its lie at the outlets of the right and left ventricle, respectively. By closing after the ventricle empty, these valves prevent reflux to the heart lower chambers.

The heart, functioning as two separate pumps, circe rulates oxygenated blood to all body parts of follows. The right side of the hearts receives blood after its deposited oxygen and nutrients throughout the body tissues. The right atrium pumps this deoxygenated blood into the pulmonary arteries that carry it back to the lungs. In the lungs, the blood sheds carbon dioxide and pick up a fresh supply of oxygen. The left side of the heart receive this newly oxygenated blood and pumps it through the aorta and back into the systemic circulation.

A vast network of five distinct types of blood vessels transport blood throughout the body. The review of each type are :
1. Arteries As these vessel carry blood away from the heart, their thick muscular walls expand and contract to accommodate the speed, pressure, and volume of blood being pumped. The aorta, which is the largest artery, gives rise to many branches that eventually divide into smaller vessels called arterioles.
2. Arterioles Although arteriolar walls are thinner than those of arteries, their muscular, elastic quality allows them to reduce the pressure and regulated the blood flow into smaller brances called capillaries.
3. Capillaries A single layer of of endothelial cells makes up these microscopic vessels. But despite their size, capillaries play a major role in the circulatory network by oxygenating body tissues and removing carbon dioxide and other wastes. Waste laden blood drains from capillaries into the venules.
4. Venules These vessel which have thinner walls and smaller diameter than arteriole, carry deoxygenated blood to the veins.
5. Veins Vein carry blood back to the right side of heart. Though their walls are thinner than those of arteries, their diameter are considerably larger. Both veins and venules are capacitance vessels, capable of accommodating increase in cardiac output byexpending to hold greater blood volume. Among the largest veins in the body are the superior vena cava, which return blood to the heart from the upper body the inferior vena cava, which return blood from the lower body, and the coronary sinus, which return body from the heart muscle. Many veins in the extremities and neck have valves that open in the direction of the blood flow and orevent reflux.

In human, as in mammals, there are two distinct circuits within the cardiovascular system knows as the systemic and pulmonary circulations. Both circulations originated and terminate in the heart, which is it functionally divided into two pumps. The systemic circulation supplies all the body tissues, and is where exchange of nutrient and product of metabolism occurs, all the blood for the systemic circulation leaves the left side of the heart via the aorta. Then, this large artery divided into smaller artery that deliver blood to all tissues and organs. These arteries divided into smaller and smaller vassels. The smallest branch called arterioles. The arterioles themselves branch into some of very small thin vessel called the capillary, where the exchange of gasses, nutrient, and waste product occurs. Exchange occurs by diffusion of substance down concentration and pressure gradient. The capillaries then unite to form larger vessels, venules which in turn unite to form fewer and larger vessels, known as veins. The pulmonary circulation is where oxygen and carbon dioxide exchange between the blood and alveolar air occurs.
The left side of the heart supplies the systemic circulation, and the right side supplies the pulmonary circulation. The systemic circulation is much larger than pulmonary circulation and those force generated by the left side of the heart is much greater than the right side one.

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