The Circulatory System

                The circulatory system is an essential part of your body. If it weren’t for your circulatory system, blood wouldn’t flow through your body. Blood carries oxygen which is necessary for “cellular respiration,” which is the process in which energy for a cell is produced. If you couldn’t produce energy you would die because none of your organs or systems would be able to function. Without the circulatory system, humans wouldn’t survive.

                The circulatory system consists of many different blood vessels. Arteries carry oxygenated blood away from the heart but one artery, the pulmonary artery, carries deoxygenated blood. Veins carry deoxygenated blood toward the heart but just like arteries, the pulmonary vein carries oxygenated blood. Since veins don’t have the pressure from the heart’s pump to direct the blood one direction, the veins have valves inside of them that direct the blood one way. Lastly we have capillaries which are the site of gas exchange and the most plentiful blood vessel; since every cell needs to exchange gases, every cell has to be contacting a capillary.

http://en.wikipedia.org/wiki/Circulatory_system

                Flowing through these blood vessels are many different types of blood cells. Red blood cells or “Erythrocytes” contain haemoglobin which allows them to carry lots of oxygen to your cells and lots of carbon dioxide away from your cells. White blood cells or “Leukocytes” fight diseases and foreign agents in the body; for example, if you get a cut and some dirt gets inside the wound then your white blood cells break down the dirt. We also have platelets or “Thrombocytes” which clot blood by making a net that traps the blood cells, they also heal wounds after clotting the blood. Blood which seems to be made of one substance is actually made up of many different substances.

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                Various organs are involved in the circulations of blood. The lungs are where red blood cells get their oxygen from and where they get rid of carbon dioxide. The pulmonary blood vessels go to and from the lungs; the heart pumps the blood through the pulmonary arteries to the lungs and gets it back via the pulmonary veins. The heart pumps blood through your blood vessels, without your heart all of your blood would collect at your feet because of gravity. Also, every cell has to be contacting a capillary, so in a sense every organ has something to do with the circulatory system,