Capillaries (Lat. Capillahs - Hair-like)

Capillaries (lat. Capillahs - hair-like) are microscopic vessels with very thin walls that penetrate tissue and connect arteries with veins. They are part of the circulatory system and play an important role in the metabolism between blood and tissues.

The capillaries are very thin, their diameter is only a few micrometers, which allows them to penetrate into the smallest corners of tissues. The walls of capillaries consist of a single layer of endothelium, which covers the inner surface of the vessel. The endothelium is highly permeable, which allows molecules and ions to pass from the blood to the tissue fluid and vice versa.

The function of capillaries is to exchange substances between blood and tissues. Capillaries supply tissues with oxygen and nutrients, transferring them from the blood to the tissues. They also remove carbon dioxide and other metabolic waste from tissues, transporting them back into the blood for further processing in the excretory organs.

Capillaries play a key role in regulating blood flow in the body. They can expand and contract in response to changes in the external environment and tissue needs for oxygen and nutrients. For example, capillaries in muscles can dilate during physical activity to increase the supply of oxygen and nutrients to muscle tissue.

However, capillaries can also cause some diseases. For example, inflammation of the capillaries can lead to poor circulation and tissue damage. Also, damage to the walls of the capillaries can lead to their leakage and the formation of edema.

In general, capillaries are an important part of the circulatory system and play a key role in the exchange of substances between blood and tissues. Their structure and functions are studied in various fields of science, including physiology, medicine and biology.