Navigation Links

Excretion is the biological process by which an organism separates waste products from its body. The waste products are then usually expelled from the body by elimination.

In mammals, for example, the two major excretory processes are the formation of urine in the kidneys and the formation of feces in the intestines. The waste products are eliminated by urination and defecation respectively.

While urine and feces are both waste material of body processes, they are in completely different categories. Urine is a waste product of the urinary system process while feces are waste products of the digestive system. Feces may contain about one-third bacteria, most of which are harmless, even beneficial while in the gut, but dangerous to others and they may also contain virulent and even deadly pathogens in the form of bacteria, viruses, amoebae, and various parasitic worms. Urine, on the other hand, contains excess water, salt, and protein waste in the form of urea as uric acid, and seldom any pathogens; should a person be in a situation of insufficient water and in danger of overheating due to lack of persperation, urine may be safely used to dampen clothing to aid cooling. It is futile to attempt to drink it (or salty ocean water), as it requires more water from the body to excrete the salt than is available in the fluid. Some sea birds are able to efficently excrete excess salt through the tear ducts associated with the eyes. Such birds can drink sea water without harm.

In insects, a system involving Malpighian tubules is utilized to excrete metabolic waste. Metabolic waste diffuses or is actively transported into the tubule, which transports the wastes to the intestines. The metabolic waste is then released from the body along with fecal stuffs.

See also


(Date:5/16/2016)... --  EyeLock LLC , a market leader of iris-based ... IoT Center of Excellence in Austin, Texas ... embedded iris biometric applications. EyeLock,s iris authentication ... with unmatched biometric accuracy, making it the most proven ... platform uses video technology to deliver a fast and ...
(Date:4/28/2016)... BANGALORE, India , April 28, 2016 ... of Infosys (NYSE: INFY ), and Samsung SDS, ... partnership that will provide end customers with a more ... payment services.      (Logo: ) ... financial services, but it also plays a fundamental part in ...
(Date:4/19/2016)... April 20, 2016 The new ... a compact web-based "all-in-one" system solution for all door ... reader or the door interface with integration authorization management ... control systems. The minimal dimensions of the access control ... the building installations offer considerable freedom of design with ...
Breaking Biology News(10 mins):
Other biology definition