Definition When we talk about capillaries (hair vessels), we usually mean the blood capillaries, although we must not forget that there are also lymph capillaries. Blood capillaries are one of three types of vessels that can be distinguished in humans. There are the arteries that transport the blood away from the heart and the veins … Read more

Functions of capillaries | Capillary

Functions of capillaries The function of the capillaries is mainly mass transfer. Depending on where the capillary network is located, nutrients, oxygen and metabolic end products are exchanged between the bloodstream and the tissue. Nutrients are supplied to the tissue, waste products are absorbed and carried away. Depending on the oxygen requirement of a particular … Read more


The endothelium is a single-layer layer of flat cells that lines all vessels and thus represents an important barrier between intravascular and extravascular space (as the space inside and outside the blood vessels). Structure The endothelium forms the innermost cell layer of the intima, the inner layer of the three-layer wall structure of an artery. … Read more

Classification | Endothelium

Classification The endothelium can be divided into different basic types. The different types depend on the function of the organ. The structure has a strong influence on the permeability of the endothelium (endothelial permeability) for the substances found in blood and tissue. The closed endothelium is most common. Among others, especially in capillaries and other … Read more

Malfunctions | Endothelium

Malfunctions Various risk factors such as arterial hypertension, increased cholesterol levels and especially nicotine consumption seriously alter the function of the intact endothelium. One speaks then of an endothelial dysfunction. For example, oxidative stress can alter the nitric oxide mechanism and highly toxic metabolites are formed which can damage the endothelium. Endothelial damage is the … Read more


Definition The lymph (lat. lympha = clear water) is a watery light yellow liquid, which is located in the lymphatic vessels. The lymph is a tissue fluid pressed out of the blood vessels. The many individual lymph vessels and lymph nodes are collectively known as the lymphatic system and, along with the bloodstream, are the … Read more