Blood vessel

Blood vessels are important tubes in our bodies that carry blood. They move blood cells, nutrients, and oxygen to most parts of our body, and they also take away waste and carbon dioxide. Some parts of the body, like cartilage, the lining of our bodies, and parts of the eye, do not have blood vessels and are called avascular.

There are five main types of blood vessels. Arteries carry blood away from the heart. Arterioles are smaller tubes that help control blood flow. Capillaries are tiny tubes where water and chemicals are exchanged between the blood and body tissues. Venules are small tubes that collect blood from capillaries, and veins carry blood back to the heart from the capillaries. The word vascular comes from the Latin word vas, meaning vessel.

Etymology

The word artery comes from old words starting with "arteria" in Latin and Greek, which might mean "to raise."

The word vein has roots in Middle English and Old French, from the Latin word "vena."

The word capillary started being used in the mid-1600s. It comes from the Latin word "capillaris," related to "capillus," meaning "hair," and was also shaped by the Old French word "capillaire."

Structure

Arteries and veins are made of three layers. The middle layer is thicker in arteries than in veins.

The inner layer is the thinnest and made of flat cells. The middle layer is the thickest in arteries and has elastic fibers and muscle that help control the vessel's size. The outer layer is the thickest in veins and is made of connective tissue with nerves and small blood vessels.

Capillaries are the smallest blood vessels and consist of just one layer of cells. They connect to form pathways that allow blood to flow even if there is a blockage. Veins have special parts that stop blood from flowing backward, but arteries usually do not, except for two that come from the heart.

There are different kinds of blood vessels, including arteries, capillaries, venules, and veins. Arteries carry blood away from the heart, while veins carry blood toward the heart. Some arteries and veins have special names depending on where they are in the body.

Function

See also: Circulatory system

Blood vessels help carry blood to all parts of an animal’s body. They move oxygen from the lungs to the rest of the body and bring back blood that needs to be re-oxygenated. Blood also carries important things like nutrients and hormones to cells and takes away waste products.

Blood moves through vessels because of the heart’s pumping action. The size of blood vessels can change to control how much blood flows to different areas. This helps keep the body at the right temperature and makes sure each part gets what it needs.

Disease

Main article: Vascular disease

Blood vessels are important in many health problems. For example, cancers need new blood vessels to grow. A condition called atherosclerosis, where plaque builds up, causes many deaths from heart problems. This can lead to heart attacks, which are serious and can be dangerous.

When blood vessels become inflamed, they can sometimes break and cause bleeding. Doctors may need to use different treatments to help manage blood fats, inflammation, and blood clots.