The Circulatory System Essay -- Papers

The Circulatory System The circulatory system is one of the most important systems in the human body. It consists of the heart and blood vessels. It is what makes the blood in our body go round. The blood carries oxygen, nutrients and hormones and takes them to where they are needed and removes the waste products like carbon dioxide. The circulatory system nourishes every cell, tissue, organ and organ system in the body. There are approximately ten pints of blood constantly circulating through seventy- five- thousand miles of blood vessels. These blood vessels reach every cell in the human body. Once they reach the cells they deliver much needed oxygen and remove carbon dioxide and other poisonous waste products. The circulation to and from the lungs is called the pulmonary circulation; the circulation round the rest of the body is called the systemic circulation. On average, a red cell would go round the whole circulation in 45 seconds. Our blood is pumped to two places: the right side of the heart pumps blood to the lungs, and the left side of the heart has to work harder pumping blood to the rest of the body which is why the left side of the heart is bigger and more muscular than the right side. Blood is pumped from the heart to the lungs and then travels back to the heart, where it is then pumped to the body. To get all the way round the circulation, blood has to go through the heart twice and this is why it is known as a double circulation. Blood is carried round all parts of the body by small tubes called blood vessels. The human Circulatory system is composed of three types of vessels; arteries, veins and capil... ...ood and waste products back to the heart. The blood in the veins moves slowly due to low pressure. Semi-lunar valves are found at regular intervals throughout the veins. These force the blood to move in only one direction. The veins walls are thinner, wider, less elastic and less muscular than those of the arteries. The veins are compressed when body muscles, particularly in the limbs, move so the valves in the veins have to prevent the blood flowing backwards. The blood in most veins is deoxygenated and contains more carbon dioxide but less food than the blood in most arteries. This is because respiring cells have used the oxygen and food and produced carbon dioxide. The pulmonary veins, which return blood from the lungs to the heart, are an exception. They contain oxygenated blood and reduced level of carbon dioxide.