Editing Excretory system (section)

===Integumentary system===
{{Main|Integumentary system}}

==== Skin ====
[[Sweat gland]]s in the skin secrete a fluid waste called sweat or [[perspiration]]; however, its primary functions are temperature control and pheromone release. Therefore, its role as a part of the excretory system is minimal. Sweating also maintains the level of salt in the body.

Mammals excrete sweat through sweat glands in the [[skin]] throughout the body. The sweat, helped by salt, evaporates and helps to keep the body cool when it is warm. In amphibians, the [[lung]]s are very simple, and they lack the necessary means to the exhale like other [[tetrapod]]s can. The moist, scale-less skin is therefore essential in helping to rid the blood of [[carbon dioxide]], and also allows for urea to be expelled through diffusion when submerged.<ref name=Breathing>{{cite journal|last=Janis|first=C.M.|author2=Keller, J.C. |title=Modes of ventilation in early tetrapods: Costal aspiration as a key feature of amniotes|journal=Acta Palaeontologica Polonica|year=2001|volume=46|issue=2|pages=137–170|url=http://www.app.pan.pl/archive/published/app46/app46-137.pdf|access-date=11 May 2012}}</ref>

In small-bodied marine invertebrates, the skin is the most important excretory organ. That is particularly true for [[acoelomate]] groups like [[cnidaria]]ns, [[flatworm]]s and [[nemertea]]ns, who have no body cavities and hence no body fluid that can be drained or purified by nephrons, which is the reason acoelomate animals are thread-like (nemertans), flat (flatworms) or only consist of a thin layer of cells around a gelatinous non-cellular interior (cnidarians).<ref name=Dorit>{{cite book |title=Zoology |url=https://archive.org/details/zoology0000dori |url-access=registration |last1=Dorit |first1=R. L. |last2=Walker |first2=W. F. |last3=Barnes |first3=R. D. |year=1991 |publisher=Saunders College Publishing |isbn=978-0-03-030504-7 }}</ref>

==== Eccrine ====
Like sweat glands, [[eccrine]] glands allow excess water to leave the body. The majority of eccrine glands are located mainly on the forehead, the bottoms of the feet, and the palms, although the glands are everywhere throughout the body. They help the body to maintain temperature control. Eccrine glands in the skin are unique to mammals.{{Citation needed|date=May 2015}}

Secretions of sweat from the eccrine glands play a large role in controlling the body temperature of humans. Regulation of body temperature, also known as [[thermoregulation]], is very important when it comes to instances that bring the body's temperature outside of the homeostatic temperature such as with a fever or even exercise.<ref>{{Cite journal|last=Charkoudian|first=Nisha|date=2003|title=Skin Blood Flow in Adult Human Thermoregulation: How It Works, When It Does Not, and Why|journal=Mayo Clinic Proceedings|volume=78|issue=5|pages=603–612|doi=10.4065/78.5.603|pmid=12744548|doi-access=free}}</ref> Together these glands make up the size of about one kidney and in one day a human can perspire amounts as much as 10 liters. The two functions consist of secretion of a filtrate in response to acetylcholine and reabsorption of sodium near the duct when there is water in excess so that a sweat can be surfacing the skin.<ref>{{cite book |doi=10.1007/BFb0037089 |chapter=The physiology, pharmacology, and biochemistry of the eccrine sweat gland |title=Reviews of Physiology, Biochemistry and Pharmacology |date=1977 |last1=Sato |first1=Kenzo |volume=79 |pages=51–131 |pmid=21440 |isbn=978-3-540-08326-9 }}</ref>

There are three parts to the eccrine sweat gland and these are the pore, the duct, and the gland. The pore is the portion that goes through the outermost layer of the skin and is typically 5-10 microns in diameter. The duct is the part of the sweat gland that connects dermis cells to the [[epidermis]]. It is composed by two layers of cells and is between 10 and 20 microns in diameter. The gland does the actual secretion and it lies deep within the [[dermis]]. The cells that make up the gland are larger in size than the duct cells and its lumen is around 20 microns in diameter.<ref>{{cite journal |last1=Holyoke |first1=John B. |last2=Lobitz |first2=Walter C. |title=Histologic Variations in the Structure of Human Eccrine Sweat Glands |journal=Journal of Investigative Dermatology |date=February 1952 |volume=18 |issue=2 |pages=147–167 |doi=10.1038/jid.1952.18 |pmid=14908190 |doi-access=free }}</ref>