How long human veins are

Over the course of a lifetime, this vast system carries about a million barrels of blood throughout the body. Blood vessels work as a team. The three major types of blood vessels — arteries, veins, and capillaries — all work together, according to the NHLBI. When the heart contracts, blood is pumped into arteries that carry it away from the heart.

Arteries are connected to tiny, thin-walled blood vessels called capillaries, which allow oxygen to move from the blood into the cells of the body. Then veins carry deoxygenated blood back to the heart. Serious conditions can affect all types of blood vessels.

Most people are aware of health conditions that plague larger blood vessels, from atherosclerosis hardening of the arties to varicose veins. But even tiny capillaries can be affected.

Capillary leak syndrome is a rare disease in which the walls of these tiny blood vessels leak, flooding surrounding tissues with blood. It can lead to severe swelling and dangerously low blood pressure, according to the National Institutes of Health. Blood vessels act as a force field for the brain.

Blood vessels are part of an important defense system known as the blood-brain barrier. A network of blood vessels and tissue comprised of closely-spaced cells helps keep harmful substances from reaching the brain, the National Cancer Institute explains. The blood-brain barrier allows some essential substances, such as water, oxygen, and carbon dioxide, to pass into the brain, but keeps bacteria and other dangerous substances out.

What is the longest vein in the body? Why are our veins blue? How fast is blood pumped through our body? Several thousand maybe? How about 60, miles. Every day the average human heart pumps over gallons of blood through veins and other vessels.

This means that by the time an individual hits 75 years old, their veins would have been responsible for moving …wait for it… Veins are great temperature regulators too.

When cold, veins will constrict to conserve energy and heat. Naturally, the harder your veins are working the more strain it puts on your heart. On the negative side, this same process can lead to corneal neovascularization , in which new blood vessels invade the cornea from the limbus, a part of the eye where the cornea meets the sclera—the white part of the eye.

The extra blood vessels can cause inflammation and scarring of the cornea, and even result in blindness. German physician Werner Forssmann performed a cardiac catheterization on himself in In this procedure, a thin tube called a catheter is inserted into one of the large blood vessels in the arm that leads to the heart.

The medical community at the time believed studying the heart was highly unorthodox, but Forssmann was determined to prove them wrong.

If the procedure succeeded, Forssmann would be able to show that a catheter could assess the pressure in the organ and how well the heart is working.

He made an incision on the inside of his left elbow and threaded the thin tube into his heart—and had a technician take an X-ray to prove the penetration was a success. Then he calmly removed the catheter from his arm with no side effects. Now, "it's a procedure performed in the U. Forssmann also went on to win the Nobel Prize for Medicine in , shutting up his detractors.

Veins return oxygen-depleted blood back to the heart against the force of gravity. Chronic venous insufficiency is more common in people who are obese, pregnant, or who have a family history of the problem. It can also be caused by high blood pressure in the leg veins, as a result of sitting or standing for long stints; not enough exercise, smoking, or deep vein thrombosis blood clots.

Depending on the severity, treatments may range from medication to surgery. When venous valves are damaged, blood can flow in the wrong direction and lead to stretched-out, bulging veins, Gregory P.

Varicose veins, which can range in color from purplish to neutral, appear twisted and gnarled, and may be raised on the skin's surface. Don't confuse them with spider veins , which are clusters of bluish or reddish veins near the surface of the skin that resemble webs, hence the name.