kapillaariverkkoja

Kapillaariverkkoja, the Finnish term for capillary networks, refer to the smallest blood vessels that form a dense meshwork between arterioles and venules. These networks provide the critical interface for the exchange of gases, nutrients, and waste products between the bloodstream and surrounding tissues. Capillary walls consist of a single layer of endothelial cells, which allow diffusion of oxygen, carbon dioxide, glucose, electrolytes, and other small molecules.

In most organs, capillaries are arranged in a hierarchical system: arterioles branch into smaller arterioles, then into capillary beds, and finally into venules. The diameter of a typical capillary ranges from 5 to 10 micrometres, allowing red blood cells to move through in a single file while perfusing adjacent cells. The structure of the capillary walls can vary: continuous, fenestrated, or sinusoidal, each suited to the functional demands of the tissue. For example, liver sinusoids permit the passage of plasma proteins, whereas brain capillaries have tight junctions making up the blood‑brain barrier.

Regulation of blood flow through capillary networks is mediated by local metabolic demands. Myogenic responses, neurogenic control, and chemical mediators such as nitric oxide and endothelin influence vascular tone. Capillaries also participate in inflammatory responses; leukocytes can adhere to endothelial cells and transmigrate into tissues during inflammation.

Abnormalities in capillary networks, including capillary leakage, dysangiogenesis, or rarefaction, underlie various diseases. Diabetic retinopathy, chronic kidney disease, and tumor angiogenesis are linked to impaired capillary remodeling or permeability. Understanding the microvascular architecture of kapillaariverkkoja is essential for elucidating normal physiology and developing therapeutic strategies for vascular disorders.