Excretion is any process which gets rid of unwanted metabolic products.
The main organs concerned with excretion in the body are the kidneys . They are situated just above the hips at the back of the abdomen and are then connected via the ureter to the bladder which is then connected to the urethra. The kidneys are supplied with blood from the renal artery. The most important structure in the kidneys are the microscopic nephrons, which are the units that filter the blood to produce urine. The increased pressure forces the filtrate through the pores in Bowman's capsule into the proximal tubule.