Kidney Excretory Organs of Humans

 The paired kidneys are the excretory organs of humans. They remove unwanted nitrogenous substances like urea and other ammonium compounds from the blood. they also maintain the osmotic pressure of the blood by controlling the excretion of water and salts.

       The kidney is supplied with blood vessels. The renal artery enters the kidney. It arises directly from the dorsal aorta and brings oxygenerated blood containing excretory products. The renal vein drains filtered deoxygenated blood from the kidney to the posterior vena cavae. A narrow tube, the ureter, connects the kidney to the urinary bladder. Urine is stored in the urinary bladder. The urinary bladder leads to the urethra which opens to the exterior.


       The kidney has two distinct regions, an outer cortex and an inner medulla. More than a million fine narrow tubules, the urinary tubules pass through both these regions. They open at the tips of triangular shaped masses of tissues called pyramids. The pyramids open into a funnel shaped cavity called the pelvis. The pelvis is continuous with the ureter. The kidney has many tiny capillaries which are branches of the renal artery and vein.