Kapillærveggen

Kapillærveggen refers to the wall of a capillary, the smallest type of blood vessel in the circulatory system. These microscopic vessels are crucial for the exchange of substances between the blood and the surrounding tissues. The wall of a capillary is extremely thin, typically only one cell thick. This single layer of endothelial cells provides a very short diffusion distance, facilitating the efficient transport of oxygen, nutrients, waste products, and other molecules.

The structure of the capillary wall varies slightly depending on the type of capillary. Continuous capillaries, the most common type, have a complete wall with tight junctions between endothelial cells. Fenestrated capillaries have pores or fenestrations within the endothelial cells, allowing for faster diffusion of smaller molecules. Sinusoidal capillaries, found in organs like the liver and spleen, have larger gaps and an incomplete basement membrane, enabling the passage of larger molecules and even cells.

Despite its thinness, the capillary wall is not a passive barrier. The endothelial cells themselves can regulate the passage of substances through various mechanisms, including transcytosis. The composition of the basement membrane surrounding the endothelial cells also plays a role in filtering molecules. The permeability of the capillary wall is a dynamic property that can be influenced by physiological factors such as inflammation and hormonal signals. Understanding the structure and function of the kapillærveggen is fundamental to comprehending tissue perfusion, nutrient delivery, and waste removal in the body.