The capillary is the finest human blood vessel. It is essential for supplying nutrients and oxygen to organs and is a vital part in the bloodstream.
What are capillaries?
The capillary is the smallest human blood vessel and participates in the so-called microcirculation. The thickness of its inner wall layer is only one cell. These microvessels are 5-10 μm in diameter and connect arteries with veins, providing for the exchange of water, oxygen, carbon dioxide, and many other nutrients and chemical waste products between the blood and the tissues surrounding it. During embryonic development, new capillaries are formed by vasculogenesis, a process of blood vessel formation within which new endothelial cells are formed and expanded into vascular channels. The term angiogenesis, in turn, refers to the formation of new capillaries by sprouting or fission processes from pre-formed blood vessels.
Anatomy and structure
Blood flows through arteries away from the heart. These branch and constrict further to form arterioles and, in a further stage, capillaries. After blood has passed through this stage in the circulation, it flows from capillaries through dilated venules to veins and with them back to the heart. Capillaries do not function independently. The capillary bed is an intertwined network of capillaries that supply a single organ. The greater the metabolism of the organ cells, the more capillaries are needed to provide nutrients and dispose of waste products. The capillary bed can consist of two different vessels: the true capillaries, which are responsible for the actual exchange between cells and circulation. In addition, the capillary bed also contains the vascular shunt, a short vessel that connects a venule directly to an arteriole.
Function and Tasks
Capillaries function in one sense as a form of communication between arteries and veins. But they are also small blood vessels, transporting blood and supplying various organs. A network of capillaries responsible for supplying individual organs is called a capillary bed. Countless of these exist in the human body. They supply the organs with amino acids, proteins and most importantly: oxygen. Without which the organs could neither fulfill their tasks nor survive. In addition to their function as suppliers of essential nutrients through the blood, capillaries act as disposers of by-products of organic production. This waste is absorbed by them and passed on for elimination from the body. The amount of capillaries in the human body is impressive. If the length of all capillary vessels in the body of a human adult could be combined, the length would be 40,000 kilometers. Capillaries and their part in metabolism are essential for the health and existence of the human organism.
Diseases and ailments
A noticeable but rather cosmetic complaint related to capillaries is redness in the skin, which occurs when capillaries are injured. Redness on the face, usually on the cheeks or nose, is very familiar. This usually happens due to too rapid narrowing and/or widening of the vessels, which eventually leads to ruptures in the vessel walls. Thin and sensitive skin is particularly susceptible to these reactions. External conditions that can be avoided to curb these symptoms are: hot environment; strong wind blowing into the face; long, intense sun exposure; rapid temperature change; squeezing and bruising of the skin. Certain moles are also due to such discoloration under the skin. There is no health risk whatsoever. But if the redness is found on noticeable parts of the body, it can be treated with laser therapy. Among the far more serious conditions affecting the capillaries is capillary leak syndrome. Due to far unexplained changes in the walls of the capillaries, increased blood plasma suddenly leaks out and enters the surrounding muscle tissue or other body cavities. If left untreated, these effects lead to a sharp drop in blood pressure, then organ failure and death. Capillary leak syndrome is an extremely rare condition. As of 2002, only about 60 cases have been documented.
