Urea - Urea is produced in the
liver tissue, consequently the hepatic vein which removes blood from the liver has a high concentration of urea. Urea within the blood is highest within the renal artery, where it is then excreted from the body.
Organic Nutrients - Glucose etc, are absorbed in the
small intestine consequently the hepatic portal vein which carries materials from the small intestine to the liver has a high concentration of these nutrients. The concentration remains high in the arteries, and falls in the veins as the sugars have been delivered to cells via the capillaries (from the arteries).
Hormones - Are produced by the
endocrine tissue upon need within the body and thus concentrations within the body can fluctuate.
Oxygen - Oxygen’s concentration is greatest in the pulmonary vein, which transports newly oxygenated blood from the
lungs to the heart. The concentration of oxygen falls in the capillaries as oxygen diffuses into cells, and then the veins obviously have a low oxygen concentration as they carry de-oxygenated blood back to the heart.
Hope that helps
