Kapillarwänden

Kapillarwänden refers to the walls of capillaries, which are the smallest blood vessels in the circulatory system. These incredibly thin structures are crucial for the exchange of substances between the blood and the surrounding tissues. The wall of a capillary is typically composed of a single layer of endothelial cells. This single-cell thickness is the key to their function, allowing for efficient diffusion of oxygen, carbon dioxide, nutrients, and waste products.

The endothelial cells that form the capillary walls are supported by a basement membrane, a thin layer of extracellular matrix. This basement membrane provides structural support and acts as a selective barrier, influencing which molecules can pass through. While the primary function of capillary walls is passive diffusion, there are also mechanisms for facilitated transport and even transcytosis, where larger molecules are transported across the endothelial cells.

The structure of capillary walls can vary slightly depending on their location and specific function. For instance, continuous capillaries, found in most tissues, have very few pores. Fenestrated capillaries, present in organs like the kidneys and intestines, have small pores (fenestrations) that allow for more rapid passage of fluids and small solutes. Sinusoidal capillaries, the largest type, have wider gaps between endothelial cells and an incomplete basement membrane, facilitating the passage of larger molecules and even cells, as seen in the liver and bone marrow. The integrity and function of these delicate capillary walls are vital for maintaining homeostasis and overall health.