Tubes called blood vessels make up an intricate and complex system that carries blood throughout the body. There are almost 60,000 blood vessels at work in the human body. Blood vessels, the heart and the lungs make up the circulatory system and ensure healthy body function.
Function
Blood flows through blood vessels to the lungs, dropping off carbon dioxide and picking up oxygen. This happens when you breathe in and out. A similar process takes place when blood flows through the blood vessels leading to and from organs of the body to the heart. Oxygen and nutrients are dropped off, toxins are picked up from the organs, and then blood returns to the heart.
Types
The vascular system, or blood vessels, contains three types of vessels--arteries, veins and capillaries. Of these three, arteries are the thickest, veins are a little thinner, and capillaries are so thin nutrients can pass directly through them. All three types of blood vessels are necessary for proper body function.
Process
The arteries carry blood full of oxygen from the heart to other organs in the body. Arteries are red in color because the blood they transport has oxygen in it. Arteries are thicker because blood flows through them with tremendous force.
Blood vessels that are very small (those located farther away from the heart) are called capillaries. Capillaries connect arteries and veins and carry blood to and from the trillions of cells in the body.
Veins carry blood low in oxygen back to the heart from other organs. Veins are blue because the blood they carry is not oxygen rich. Their walls are not as thick because the blood going through them flows at a slower rate.
Size
The inferior vena cava and the superior vena cava, which put blood into the heart's right atrium, are the two largest veins in the body. The aorta is attached to the left ventricle of the heart, and is where all other arteries start. It is the largest artery in the body.
Considerations
Certain medical conditions cause the vascular system to function improperly. These conditions include heart disease, stroke, high blood pressure, congenital defects, diseases of the arteries or capillaries, rheumatic heart disease and diseases of the veins. While some of these are caused by problems beyond a person's control, people can lessen the chances of getting others such as heart disease, high blood pressure and stroke by eating a healthy diet and staying active.
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