The Cardiovascular System

The heart, blood and blood vessels make up the basis of the cardiovascular system also known as the circulatory system. The average human body contains approximately 5 litres of blood which is carried around the body via a network of blood vessels split into three types; arteries, veins and capillaries. The arteries are the largest of the three vessels and carry blood away from the heart. Veins carry blood to the heart and are smaller than arteries, then finally the smallest vessels known as capillaries distribute the oxygen rich blood to organs whilst simultaneously picking up the waste carbon dioxide and water from the organs to transport back to the heart where it can be pumped into the lungs to be exhaled.

Blood actually has multiple components: Red blood cells are the transport mechanism that carry vital materials such as nutrients and oxygen to cells in the body, and remove the waste and unused bi-products produced by organ and body function. Haemoglobin in blood carries the oxygen molecules around the circulatory system. They oxygen binds to the iron in the blood cells and gives blood its red colour. As the blood is diffused across the membranes of the capillary walls and into the cells of organs, the level of carbon dioxide is diffused back as waste from cells to the blood cells where it can be transported to the excretory organs, as well as repeat it’s reoxygenation process in capillaries of the lungs. Red blood cells are transported around the blood vessels in a straw-like fluid called plasma. Blood also contains bacteria fighting white blood cells of which there are fewer than red blood cells, but they are larger in size. If the walls of the blood vessels are breached, platelets in the blood composition help to form a ...

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...ght side. Blood enters the left atrium, passes through a valve and enters the left ventricle, is pumped through another valve and pumped out of the heart to the organs for transportation of oxygen and nutrients. The blood is forced down the vessel network from the heart via arteries, veins and capillaries where the oxygen and nutrient rich blood exchanges and picks up deoxygenated blood and waste from the organs, At this point the cycle changes back to the pulmonary circulation and the entire process repeats.

The cardiovascular system, at the same time as pumping oxygenated blood in and out of the heart, also transports nutrients to, and waste products from, other parts of the body. The other systems in the body such as the digestive, respiratory and nervous systems are linked and function due to their connection with this circulation of the cardiovascular system.