Chapter-11 Urinary System The urinary system is the main excretory system of the body. It consists of 1) two kidneys 2) two ureters 3) an urinary bladder 4) an urethra. Kidney: Mesodermal in origin. Right kidney slightly lower than the left kidney due to presence of liver on right hand side. They are two bean shaped organs lying on the posterior abdominal wall, on each side of the vertebral column. External structure of kidney 1. Reddish brown in colour 2. Bean shaped 3. 11cm×5cm×3cm dimension 4. 150gm in weight each kidney 5. Consists of hilum through which renal artery enter and renal vein and ureter leaves from kidney 6. Outer border is convex, inner border is concave which contain hilum. Internal structure of kidney 1. An outer cortex which is reddish- brown in colour. 2. Inner medulla which contains pyramids of the kidney. 3. An upper expanded end of ureter called pelvis. 4. There are several pyramids which drain urine to minor calyx. The 4to 5 minor cal