Changes

====Avian Renal Portal System====

====Avian Renal Portal System====

In birds the blood from the hindlimbs is carried directly to the kidneys.  It bypasses the glomeruli and waste products in the blood are secreted directly into the tubules.  This is thought to be a more efficent way to excrete uric acid and urate.  It is of significance when injecting these animals if the injection is given in the caudal half of the body most of the drug will be potentially lost in the urine before it has time to act it may also be toxic to the kidney as it has not been metabolised by the liver

In birds the blood from the hindlimbs is carried directly to the kidneys.  The cranial and caudal renal portal veins deliver blood from the hindlimbs into the capillary beds of the interlobar arteries.  Therefore blood which has already been through capillary beds in the hind limbs mixes with blood directly from the heart.  It bypasses the glomeruli and waste products in the blood are secreted directly into the tubules.  This is thought to be a more efficent way to excrete uric acid and urate.  A portal valve regulates how much blood from the hindlimbs passes through the kidneys.  When open very little blood enters the capillary beds as it follows the path of least resistance.  If the valve narrows then blood is forced into the capillary beds.  However some blood always escapes thanks to connections with both the caudal mesenteric veins and veterbral sinuses. It is of significance when injecting these animals if the injection is given in the caudal half of the body most of the drug will be potentially lost in the urine before it has time to act it may also be toxic to the kidney as it has not been metabolised by the liver

====Other Roles of the Avian Kidney====

====Other Roles of the Avian Kidney====