Excretion is the removal of excess minerals from the body(removing toxic substances) waste products of metabolism.(urea is a waste product of metabolism.)

Excretive organs are- kidneys Urea, water, saltsLiver bile

pigmentsLungs carbondioxide,waterSkin(sweatglands) sweat

EXCRETION

Normally there are two kidneys commonly referred to as left and right kidney.Each kidney has an arterial blood supply (the left and right renal arteries) which are branches of the aorta.Each kidney has a vein (left and right Renal Vein) which returns filtered blood to the Vena Cava and therefore the general circulation.

The urine produced by each kidney is transported by each ureter to the bladder.

LONGITUDINAL SECTION OF A KIDNEY