Medical Questions » Arteries and Veins Questions » Question No. 72
| Question: | What is the difference between an artery and a vein? ! am confused about why different blood vessels have different names. |
| Answer: | When the heart contracts, it pumps blood out into arteries under considerable pressure. The blood travels along these arteries, which divide into smaller and smaller ones (arterioles), until they finally branch into microscopically thin vessels called capillaries.
Every cell in the body is in direct contact with a capillary, and can obtain oxygen and nutrients from the blood, while giving back waste products.
The blood moves out of capillaries into very small blood vessels called venules, which join up to form veins. The blood travels slowly at low pressure back to the heart through steadily larger veins. Once in the heart, the blood is pumped through the lungs to be enriched with oxygen, then returns to the heart again to be pumped out into the body through the arteries again, completing the cycle.
Because the blood in arteries is moving quickly under high pressure, arteries have thick walls containing muscle fibres. Veins are far thinner and softer, as blood in them is not under any significant pressure, but because they are weaker, those that do have an increase in pressure, for example in the legs, can dilate and form varicose veins. |
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