Sweat gland
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This article needs additional citations for verification. (March 2010) |
| Sweat gland | |
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| A cross-section of the human skin, with the sweat gland labeled at the bottom | |
| Latin | Glandula sudorifera[1][2] |
| Gray's | subject #234 1063 |
| System | Integumentary[3] |
| Nerve | Eccrine: cholinergic sympathetic nerves[4] Apocrine: adrenergic nerves[5] |
| Precursor | Ectoderm[3] |
| MeSH | Sweat+Glands |
Sweat glands (also known as sudoriferous or sudoriparous glands, from Latin sudor, meaning "sweat"),[6][7] are small tubular structures of the skin that produce sweat. There are two main types of sweat glands:
- Eccrine sweat glands are distributed almost all over the body, though their density varies from region to region. Humans utilize eccrine sweat glands as a primary form of cooling.[8]
- Apocrine sweat glands are larger, have a different secretion mechanism, and are mostly limited to the axilla (armpits) and perianal areas in humans. Although apocrine glands contribute little to cooling in humans, they are the only effective sweat glands in hoofed animals such as the camel, donkey, horse, and cattle.[9][10][11]
Domestic animals[which?] have apocrine glands at the base of each hair follicle but eccrine glands only in foot pads and snout. Their apocrine glands, like those in humans, produce an odorless oily milky secretion evolved not to evaporate and cool but rather coat and stick to hair so odor-causing bacteria can grow on it.[12] Eccrine glands on their foot pads, like those on palms and soles of humans, didn't evolve to cool either but rather increase friction and enhance grip.
Both apocrine and eccrine sweat glands contain myoepithelial cells (from Greek myo– "muscle"), specialized epithelial cells located between the gland cells and the underlying basal lamina. Myoepithelial cell contractions squeeze the gland and discharge the accumulated secretions. The secretory activities of the gland cells and the contractions of myoepithelial cells are controlled by both the autonomic nervous system and by the circulating hormones.
Ceruminous glands, which produce ear wax, and mammary glands, which produce milk, and ciliary glands in the eyelids are considered to be modified sweat glands.[2][13]
Contents |
Structure [edit]
Sweat glands are simple tubules consisting of a base rolled into a glomerulum and a duct that carries the sweat away.[14] The base, which forms the secretory coil, is set deep in the hypodermis, and the entire gland is surrounded by adipose tissue.[2][15][16] In apocrine glands, the secretory tubule is branched and single-layered, whereas it is unbranched, coiled, and double-layered in eccrine glands.[7][17] All sweat glands' secretory coils are wrapped in long, rod-like contractile myoepithelial cells.[17][18] In apocrine and eccrine glands, the diameter of the overall coil is around 800 and 500–700 microns respectively. The tubules themselves are also wider in apocrine glands: they have an inner diameter of 80–100 microns, versus the 30–40 micron diameters in eccrine glands.[19] Excretory ducts, which carry sweat away from the secretory coil, are lined by a double layer of cuboidal cells.[20]
Each sweat gland receives several nerve fibers that branch out into bands of one or more axons and encircle the individual tubules of the secretory coil. Capillaries are also interwoven among sweat tubules.[21]
Types [edit]
Apocrine [edit]
The name apocrine was originally chosen because it was believed that the gland cells used an apocrine method of secretion. Although it is now known that their secretory products are produced through merocrine secretion, the name has not changed. Apocrine sweat glands are coiled tubular glands that produce a viscous, cloudy and potentially odorous secretion. Apocrine sweat glands discharge in the canals of hair follicles. They begin secreting at puberty; the sweat produced may be acted upon by bacteria, causing a noticeable odor. Apocrine gland secretions may also contain pheromones, chemicals that communicate information to other individuals by altering their hormonal balance. Some research has indicated that feminine secretions from apocrine sweat glands can alter the menstrual timing of other women (this is called the McClintock effect), though the research methods used have been criticized. The significance of human pheromones and the role of apocrine sweat gland secretions in humans remains incompletely understood.
Eccrine [edit]
Eccrine sweat glands are smaller than apocrine sweat glands, and they do not extend as deep into the dermis. Eccrine sweat glands are coiled tubular glands that discharge their secretions directly onto the surface of the skin. Their density varies greatly according to body regions, the highest density (>250 glands/cm2) being on soles, palms, and scalp.
The clear secretion produced by eccrine sweat glands is termed sweat or sensible perspiration. Sweat is mostly water, but it does contain some electrolytes, since it is derived from blood plasma, although less concentrated. It therefore contains mainly sodium chloride, but also other electrolytes. The presence of sodium chloride gives sweat a salty taste. The total volume of sweat produced depends on the number of functional glands and the size of the surface opening. The degree of secretory activity is regulated by neural and hormonal mechanisms (men produce greater volumes of sweat than women). When all of the eccrine sweat glands are working at maximum, the rate of perspiration for a human being may exceed three liters per hour,[22] and dangerous fluid and electrolyte losses can occur.
Eccrine glands have three primary functions:
- Thermoregulation. Sweat cools the surface of the skin and reduces body temperature.
- Excretion. Eccrine sweat gland secretion can also provide a significant excretory route for water and electrolytes.[citation needed]
- Protection. Eccrine sweat gland secretion aids in preserving the skin's acid mantle, which helps protect the skin from colonisation from bacteria and other pathogenic organisms.[23]
Pathology [edit]
Tumors [edit]
Sweat gland tumors include:[24]
- Acrospiroma
- Aggressive digital papillary adenocarcinoma
- Apocrine gland carcinoma
- Ceruminoma
- Cutaneous myoepithelioma
- Cylindroma
- Eccrine carcinoma
- Hidradenoma papilliferum
- Hidrocystoma
- Microcystic adnexal carcinoma
- Mucinous carcinoma
- Papillary eccrine adenoma
- Syringadenoma papilliferum
- Syringofibroadenoma
- Syringoma
Adenolipomas are lipomas associated with eccrine sweat glands.[25]
As signs in other illnesses [edit]
- Acromegaly, a result of excess growth hormone, causes the size of of sweat glands increase, which leads to thicker skin.[26]
- Aquagenic wrinkling of the palms, in which white papules develop on the palms after exposure to water, can sometimes come with abnormal aquaporin 5 in the sweat glands.[27]
- Cystic fibrosis can be diagnosed by a sweat test,as the disease causes the sweat glands ducts to reabsorb less chloride, leading to higher concentrations of chloride in the secreted sweat.[28]
- Ectodermal dysplasia can present a lack of sweat glands.[29]
- Fabry disease, characterized by excess globotriaosylceramide (GL3), causes a decrease in sweat gland function due to GL3 deposits in the eccrine glands.[30]
- GM1 gangliosidoses, characterized by abnormal lipid storage, leads to vacuolization in eccrine sweat gland cells.[31]
- Hunter syndrome can include metachromin granules and mucin in the cytoplasm of the eccrine sweat gland cells.[32]
- Hypothyroidism's low levels of thyroid hormone lead to decreased secretions from sweat glands; the result is dry, coarse skin.[33]
- Kearns–Sayre syndrome, a disease of the mitochondria, involves abnormal mitochondria in eccrine sweat glands.[34]
- Lafora disease is a rare genetic disorder marked by the presence of abnormal polyglucosan deposits. These "Lafora bodies" appear in the ducts of sweat glands, as well as the myoepithelial cells of apocrine glands.[35]
- Lichen striatus, a self-limited eruption of small, slightly scaly papules, includes a lymphoid infiltrate around eccrine sweat glands.[36]
- Metachromatic leukodystrophy, a lysosomal storage disease, leads to the accumulation of lipopigments and lysosomal residual bodies in the epithelial cells of sweat glands.[37]
- Neuronal ceroid lipofuscinosis causes abnormal deposits of lipopigment in sweat gland epithelial cells (among other places).[38]
- Neutral lipid storage disease includes abnormal lipid deposits in cells, including those of the sweat gland.[39]
- Newmann–Pick type C, another lipid storage disease, includes abnormal lipid storage in sweat glands.[40]
- Schindler disease causes cytoplasmic vacuoles that appear to be empty or contain filamentous material to manifest in eccrine sweat gland cells.[41]
Gallery [edit]
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Notes [edit]
- ^ Federative International Committee on Anatomical Terminology (2008). Terminologia histologica: international terms for human cytology and histology. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 121. ISBN 9780781775373.
- ^ a b c Gray, Henry (1918). "The Organs of the Senses and the Common Integument". Anatomy of the Human Body (20th ed.). Philadelphia: Lea & Febiger.
- ^ a b Neas, John F. "Development of the Integumentary System". Embryology Atlas (4th ed.). Benjamin Cumings. Retrieved 17 December 2012. Text "editor1-last Martini" ignored (help); Text "editor3-lastTallitsch" ignored (help)
- ^ Krstic 2004, p. 464.
- ^ Krstic 2004, p. 466.
- ^ "sudoriferous". The New Oxford American Dictionary (2nd ed.).
- ^ a b "sweat gland". Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health (7th ed.). Saunders. 2003. Retrieved 18 December 2012.
- ^ Kurosumi 1984, p. 255.
- ^ Folk Jr & Semken Jr 1991, p. 181.
- ^ Bullard, R. W.; Dill, D. B.; Yousef, M. K. (1970). "Responses of the burro to desert heat stress". Journal of Applied Physiology 29 (2): 159. PMID 5428889.
- ^ Sørensen & Prasad 1973, p. 173.
- ^ Merck Sharp & Dohme Corp. "Cutaneous Apocrine Gland Tumors". The Merck Veterinary Manual.
- ^ Ackerman, A. Bernard; Böer, Almut; Bennin, Bruce; Gottlieb, Geoffrey J. (2005). "Embryologic, Histologic, and Anatomic Aspects". Histologic Diagnosis of Inflammatory Skin Diseases An Algorithmic Method Based on Pattern Analysis. ISBN 9781893357259.
- ^ Randall 2012, p. 255.
- ^ Caceci, Thomas. "Integument I: Skin". VM8054 Veterinary Histology Laboratory Exercises. Virginia–Maryland Regional College of Veterinary Medicine. Retrieved 19 December 2012.
- ^ Kurosumi, Shibasaki & Ito 1984, p. 255.
- ^ a b Kurosumi, Shibasaki & Ito 1984, p. 256.
- ^ Eroschenko 2008, pp. 222, 226, 228.
- ^ Wilke et al. 2007, pp. 173, 175.
- ^ Eroschenko 2008, p. 228.
- ^ Kennedy, W. R.; Wendelschafer-Crabb, G.; Brelje, T. C. (November 1994). "Innervation and vasculature of human sweat glands: an immunohistochemistry-laser scanning confocal fluorescence microscopy study". The Journal of neuroscience: the official journal of the Society for Neuroscience 14 (11 pt. 2): 6825. ISSN 0270-6474.
- ^ C.P. Hickman, L.S. Roberts and A. Larson (2001). Integrated Principles of Zoology, 11/e.
- ^ Marples, Mary J (1965). The ecology of the human skin. OL 5915977M.
- ^ James, Berger & Elston 2011.
- ^ James, Berger & Elston 2011, p. 612.
- ^ Rubin & Strayer 2011, p. 1043.
- ^ James, Berger & Elston 2011, p. 210.
- ^ Bernstein, Daniel; Shelov, Steven P. (29 July 2011). Pediatrics for Medical Students. Lippincott Williams & Wilkins. p. 504. ISBN 9780781770309.
- ^ "Ectodermal dysplasia". MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. Retrieved 2 January 2013.
- ^ Elstein, Deborah (1 January 2010). Fabry Disease. Springer. pp. 84, 358. ISBN 9789048190331.
- ^ Drut, Ricardo (1978). "Eccrine Sweat Gland Involvement in GM1 Gangliosidosis". Journal of Cutaneous Pathology 5 (1): 35–36. doi:10.1111/j.1600-0560.1978.tb00935.x. ISSN 1600-0560.
- ^ James, Berger & Elston 2011, p. 534.
- ^ Rubin & Strayer 2011, p. 1048.
- ^ Martin, J. J. (31 January 1984). "Neuropathological Diagnostic Methods". In Neetens, A.; Lowenthal, A.; Martin, J. J. Visual System in Myelin Disorders. The Netherlands: Springer. p. 367. ISBN 9789061938071.
- ^ Rubio, G.; Garcia Guijo, C.; Mallada, J. J.; Cabello, A.; Garcia Merino, A. (November 1992). "Diagnosis by axilla skin biopsy in an early case of Lafora's disease". Journal of Neurology, Neurosurgery, and Psychiatry 55 (11): 1084–1085. ISSN 0022-3050. PMC 1015298. PMID 1469407. Retrieved 18 December 2012.
- ^ James, Berger & Elston 2011, p. 223–224.
- ^ Goebel, H. H.; Busch, H. (1989). "Abnormal lipopigments and lysosomal residual bodies in metachromatic leukodystrophy". Advances in experimental medicine and biology 266: 299–309. ISSN 0065-2598.
- ^ Carlén, B.; Englund, E. (August 2001). "Diagnostic value of electron microscopy in a case of juvenile neuronal ceroid lipofuscinosis". Ultrastructural pathology 25 (4): 285–288. ISSN 0191-3123. PMID 11577772.
- ^ James, Berger & Elston 2011, p. 555.
- ^ Elleder, M.; Jirásek, A.; Smíd, F. (19 December 1975). "Niemann-Pick disease (Crocker's type C): A histological study of the distribution and qualitative differences for the storage process". Acta neuropathologica 33 (3): 191–200. ISSN 0001-6322.
- ^ Pavelka, Margit; Roth, Jurgen (1 January 2010). Functional Ultrastructure: Atlas of Tissue Biology and Pathology. Springer. p. 332. ISBN 9783211993903.
References [edit]
- Eroschenko, Victor P. (2008). "Integumentary System". DiFiore's Atlas of Histology with Functional Correlations. Lippincott Williams & Wilkins. pp. 212–234. ISBN 9780781770576.
- Folk Jr, G. Edgar; Semken Jr, A. (1 September 1991). "The evolution of sweat glands". International Journal of Biometeorology 35 (3): 180–186. doi:10.1007/BF01049065. ISSN 1432-1254 0020-7128, 1432-1254. Retrieved 18 December 2012.
- Kurosumi, Kazumasa; Shibasaki, Susumu; Ito, Toshiho (1984). "Cytology of the Secretion in Mammalian Sweat Glands". In Bourne, Geoffrey H.; Danielli, James F. Protein Diffusion in Cell Membranes: Some Biological Implications. Orlando, Florida: Academic Press. pp. 253–330. ISBN 9780123644879.
- James, William D.; Berger, Timothy G.; Elston, Dirk M. (2011). Andrews' Diseases of the Skin: Clinical Dermatology (11th ed.). London: Elsevier. ISBN 9781437703146.
- Krstic, Radivoj V. (18 March 2004). Human Microscopic Anatomy: An Atlas for Students of Medicine and Biology. Springer. pp. 464, 466–469. ISBN 9783540536666.
- Randall, Walter C. (September 1946). "QUANTITATION AND REGIONAL DISTRIBUTION OF SWEAT GLANDS IN MAN 1". Journal of Clinical Investigation 25 (5): 761–767. ISSN 0021-9738. PMC 435616. PMID 16695370. Retrieved 18 December 2012.
- Rubin, Raphael; Strayer, David Sheldon (29 March 2011). Rubin's Pathology: Clinicopathologic Foundations of Medicine. Lippincott Williams & Wilkins. pp. 1043, 1048. ISBN 9781605479682.
- Sørensen, Vibeke W.; Prasad, Gaya (1973). "On the fine structure of horse sweat glands". Zeitschrift für Anatomie und Entwicklungsgeschichte 139 (2): 173–183. doi:10.1007/BF00523636. PMID 4352229.
- Wilke, K.; Martin, A.; Terstegen, L.; Biel, S. S. (June 2007). "A short history of sweat gland biology" (pdf). International journal of cosmetic science 29 (3): 169–179. doi:10.1111/j.1467-2494.2007.00387.x. ISSN 1468-2494.
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