Excretion
Excretion is a process in which metabolic waste is eliminated from an
placental mammals, urine is expelled through the urethra,[2] which is part of the excretory system. In unicellular organisms
, waste products are discharged directly through the surface of the cell.
During life activities such as cellular respiration, several chemical reactions take place in the body. These are known as metabolism. These chemical reactions produce waste products such as carbon dioxide, water, salts, urea and uric acid. Accumulation of these wastes beyond a level inside the body is harmful to the body. The excretory organs remove these wastes. This process of removal of metabolic waste from the body is known as excretion.
Green
stomata, root cell walls, and other routes. Plants can get rid of excess water by transpiration and guttation. It has been shown that the leaf acts as an 'excretophore' and, in addition to being a primary organ of photosynthesis, is also used as a method of excreting toxic wastes via diffusion. Other waste materials that are exuded by some plants — resin, saps, latex, etc. are forced from the interior of the plant by hydrostatic pressures inside the plant and by absorptive forces of plant cells. These latter processes do not need added energy, they act passively. However, during the pre-abscission phase, the metabolic levels of a leaf are high.[3][4] Plants also excrete some waste substances into the soil around them.[5]
In animals, the main excretory products are
clear many substances from the blood (for example, in renal excretion), and the cleared substances are then excreted from the body in the urine and feces.[6]
toxic. This process is called detoxification.[7]
egg. Many avian species, especially seabirds, can also excrete salt via specialized nasal salt glands, the saline solution leaving through nostrils in the beak
.
In
Malpighian tubules is used 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 matter.
The excreted material may be called ejecta.[8] In pathology the word ejecta is more commonly used.[9]
See also
References
Wikimedia Commons has media related to Excretion.
- ISBN 0-19-914260-2.
- ISBN 978-0-226-87013-7. Retrieved 6 May 2013.
- S2CID 4344886.
- ^ "Excretion". Encyclopædia Britannica. Encyclopædia Britannica Ultimate Reference Suite. Chicago: Encyclopædia Britannica. 2010.
- ^ http://www.tutorvista.com/content/science/science-ii/excretion/excretion-plants [dead link]
- PMID 25078422.
- ^ "Excretion - General features of excretory structures and functions". Encyclopedia Britannica. Retrieved 2021-02-05.
- PMID 29613104.
- ^ "Ejecta". Oxford English Dictionary (2nd ed.). Oxford University Press. 1989.
External links
Look up excretion in Wiktionary, the free dictionary.
- UAlberta.ca, Animation of excretion
- Brian J Ford on leaf fall in Nature