Different organisms use different substances for metabolic activities and release different substances as waste products.
In human beings, these products include Carbon dioxide, water, Nitrogenous compounds like ammonia, urea, uric acid, bile pigments, excess salts, etc.
The most poisonous waste is ammonia. Kidneys eliminate a major amount of waste from the body. Hence kidneys are known as chief excretory organs.
The human excretory system parts: excretory system in humans comprises a pair of kidneys, a pair of ureters, a urinary bladder and a urethra.
Kidneys
The excretory system consists of a pair of
bean-shaped kidneys, reddish-brown in colour, located in the abdominal cavity on either side of the vertebral column.
Outer surface of the kidney is convex, and the inner surface is concave. The renal artery enters the kidney, and the renal vein leaves the kidney.
The waste products generated in various body organs are filtered and removed by the kidneys in the form of urine.
Ureters
Human excretory system contains a pair of narrow muscular tubes. Each ureter arises from the hilus of the kidney. These carry urine from the kidney to the urinary bladder.
Urinary Bladder
It is a pear-shaped structure. It stores urine brought by ureters. Its storage capacity is 300 to 800 ml.
Urethra
It discharges the urine. The opening of the urethra has a ring-like muscle. The urethra is 4cm long in females open to the vestibule and in the male, it is about 20 cm long.