The human body has various organs for the purpose of excretion.
Excretion in human beings:
1. Lungs:
Lungs excrete carbon dioxide and water vapour formed during the process of respiration.
2. Skin:
Skin removes urea, salts and excess water as sweat produced by sweat glands present in the skin. Sweat is removed through tiny pores in the skin.
3. Large intestine:
Large intestine removes the indigested food as faeces through the anus. It is a storage area of waste material that awaits elimination.
4. Urinary system:
The organs that form, store and excrete urine constitute the urinary system. It consists of a pair of kidneys, a pair of ureters, a urinary bladder and a urethra.
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The kidneys are located one on each side of the vertebral column just below the diaphragm. Each kidney is bean shaped with a concavity on the inner margin. Blood vessels, nerves and ureters arise from the kidney at this point.
Kidneys are the urine-forming organs of human beings. Urine formed in the kidneys passes down thin muscular tubes called ureters. Ureters from both the kidneys open into a muscular sac called urinary bladder. Bladder is a storage sac that releases the urine to the outside through a short tube called urethra.
Each kidney is composed of numerous tiny filters called nephrons. Bephrons are the functional units of kidneys. Each nephron is a ling-coiled tubular structure the filters out nitrogenous waste material from the blood and forms urine.
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Urea is the main nitrogenous waste present in urine. Kidneys must function properly in order to keep a person in perfect health.
The examination of urine gives an indication of the functioning of the organs in the body. The doctor asks the patients to get urine test done in order to diagnose diseases. If excess sugar, pus cells or other materials are found in urine, it suggests that some organ of the body is not functioning properly.