Bowman's capsule

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Bowman's capsule
Bowman's capsule and glomerulus.svg
Glomerulus (red), Bowman's capsule (blue) and proximal tubule (green)
Details
Precursor Metanephric blastema
Location Nephron of kidney
Identifiers
Latin capsula glomeruli
MeSH D050476
FMA 15626
Anatomical terminology

Bowman's capsule (or the Bowman capsule, capsula glomeruli, or glomerular capsule) is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form urine. A glomerulus is enclosed in the sac. Fluids from blood in the glomerulus are collected in the Bowman's capsule.

Contents

Structure

Outside the capsule, there are two poles:

Inside the capsule, the layers are as follows, from outside to inside:[ citation needed ]

Function

Diagram showing Bowman's capsule as part of the renal corpuscle Renal corpuscle-en.svg
Diagram showing Bowman's capsule as part of the renal corpuscle

The process of filtration of the blood in the Bowman's capsule is ultrafiltration, and the normal rate of filtration is 125 ml/min, equivalent to 80 times the daily blood volume.[ citation needed ] It is a major site for blood filtration (including glomerulus)

Any proteins under roughly 30 kilodaltons can pass freely through the membrane, although there is some extra hindrance for negatively charged molecules due to the negative charge of the basement membrane and the podocytes.[ citation needed ]

Any small molecules such as water, glucose, salt (NaCl), amino acids, and urea pass freely into Bowman's space, but cells, platelets and large proteins do not.[ citation needed ]

As a result, the filtrate leaving the Bowman's capsule is very similar to blood plasma (filtrate or glomerular filtrate is composed of blood plasma minus plasma protein i.e. it contains all the components of blood plasma except the proteins) in composition as it passes into the proximal convoluted tubule.[ citation needed ]

Clinical significance

Micrograph of proteinaceous material in Bowman's space, which is unspecific. It is present in about 5% of people aged over 60 years, but also in for example hypertensive kidney disease. Micrograph of proteinaceous material in Bowman's space.jpg
Micrograph of proteinaceous material in Bowman's space, which is unspecific. It is present in about 5% of people aged over 60 years, but also in for example hypertensive kidney disease.

Measuring the glomerular filtration rate (GFR) is a diagnostic test of kidney function. [3] A decreased GFR may be a sign of kidney failure.[ citation needed ]

A number of diseases can result in various problems within the glomerulus. Examples include acute proliferative (endocapillary) glomerulonephritis, mesangioproliferative glomerulonephritis, mesangiocapillary (membranoproliferative) glomerulonephritis, acute crescentic glomerulonephritis, focal segmental glomerulonephritis, and diabetic glomerulosclerosis.[ citation needed ]

History

Bowman's capsule is named after Sir William Bowman (1816–1892), a British surgeon and anatomist. [4] However, thorough microscopical anatomy of kidney including the nephronic capsule was first described by a Ukrainian surgeon and anatomist from the Russian Empire, Prof. Alexander Schumlansky (1748–1795), in his 1782 doctoral thesis "De structura renum" ("About Kidney Structure", in Latin); thus, much prior to Bowman. [5]

Together with the glomerulus it is known as a renal corpuscle, or a Malpighian corpuscle, named after Marcello Malpighi (1628–1694), an Italian physician and biologist. This name is not used widely anymore, probably to avoid confusion with Malpighian bodies of the spleen.[ citation needed ]

See also

Additional images

References

  1. Histology image:22401lba from Vaughan, Deborah (2002). A Learning System in Histology: CD-ROM and Guide. Oxford University Press. ISBN   978-0195151732.
  2. Table 4 in: Hodgin, Jeffrey B.; Bitzer, Markus; Wickman, Larysa; Afshinnia, Farsad; Wang, Su Q; O'Connor, Christopher; Yang, Yan; Meadowbrooke, Chrysta; Chowdhury, Mahboob; Kikuchi, Masao; Wiggins, Jocelyn E.; Wiggins, Roger C. (2015). "Glomerular Aging and Focal Global Glomerulosclerosis: A Podometric Perspective". Journal of the American Society of Nephrology. 26 (12): 3162–3178. doi:10.1681/ASN.2014080752. ISSN   1046-6673. PMC   4657829 . PMID   26038526.
  3. Romagnani, Paola; Anders, Hans-Joachim (2019). "Excretory System". In Brüne, Martin; Schiefenhövel, Wulf (eds.). Oxford Handbook of Evolutionary Medicine. Oxford University Press. ISBN   978-0198789666.
  4. Bowman, William; Royal Society of London. Philosophical transactions, v. 32, p. 57-80, 1842 (1842). On the structure and use of the Malpighian bodies of the kidney: with observations on the circulation through that gland. London: Taylor. OCLC   7714131.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  5. Schumlansky, Aleksander (1782). Dissertatio Inauguralis Anatomica De Structura Renum Quam Pro Licentia Summos In Medicina Honores Et Privilegia Doctoralia Legitime Obtinendi In Inclyta Argentoratensium Universitate Solenni Eruditorum Examini Submittit Alexander Schumlansky Poltawo-Russus Die XVI. Novembr. A. MDCCLXXXII (in Latin). Argentorati [Strasbourg]. p. 92.