portalæðakerfið

The portalæðakerfið, also known as the portal venous system, is a unique circulatory pathway within the body. It is a system of veins that drains blood from one capillary bed and delivers it to another capillary bed without passing through the heart first. The primary portal system in the human body is the hepatic portal system. This system collects blood from the gastrointestinal tract, including the stomach, intestines, and spleen, and transports it directly to the liver. In the liver, this nutrient-rich blood passes through sinusoids, a type of capillary, where the liver can process absorbed nutrients, detoxify harmful substances, and filter pathogens.

The hepatic portal system is crucial for digestion and metabolism. It allows the liver to receive the full complement of nutrients absorbed from the digestive system. For example, glucose, amino acids, and vitamins are transported to the liver for storage, conversion, or immediate use. The spleen, which filters blood and plays a role in the immune system, also contributes blood to the portal system. Another, less prominent, portal system is the hypophyseal portal system, which connects the hypothalamus to the anterior pituitary gland in the brain. This system allows hormones produced by the hypothalamus to be delivered directly to the pituitary gland, regulating the release of various hormones that control other endocrine glands. Understanding the portal venous system is vital in fields like medicine and physiology due to its significant role in nutrient processing and hormonal regulation.