Kidney
| Kidney | |
|---|---|
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| Human kidneys beheld from abaft with aback removed | |
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| Lamb kidneys | |
| Latin | ren |
| Gray's | subject #253 1215 |
| Artery | renal artery |
| Vein | renal vein |
| Nerve | renal plexus |
| MeSH | Kidney |
| Dorlands/Elsevier | Kidney |
The kidneys are commutual organs with several functions. They are credible in abounding types of animals, including vertebrates and some invertebrates. They are an capital allotment of the urinary system and aswell serve homeostatic functions such as the adjustment of electrolytes, aliment of acid-base balance, and adjustment of blood pressure. They serve the physique as a accustomed clarify of the blood, and abolish wastes which are absent to the urinary bladder. In bearing urine, the kidneys defecate wastes such as urea and ammonium; the kidneys aswell are amenable for the reabsorption of water, glucose, and amino acids. The kidneys aswell aftermath hormones including calcitriol, renin, and erythropoietin.
Located at the rear of the abdominal cavity in the retroperitoneum, the kidneys accept claret from the commutual renal arteries, and cesspool into the commutual renal veins. Anniversary annex excretes urine into a ureter, itself a commutual analysis that empties into the urinary bladder.
Renal physiology is the abstraction of annex function, while nephrology is the medical specialty anxious with kidney diseases. Diseases of the annex are diverse, but individuals with annex ache frequently affectation appropriate analytic features. Accepted analytic altitude involving the annex cover the nephritic and nephrotic syndromes, renal cysts, acute annex injury, chronic annex disease, urinary amplitude infection, nephrolithiasis, and urinary amplitude obstruction.1 Assorted cancers of the annex exist; the a lot of accepted developed renal blight is renal corpuscle carcinoma. Cancers, cysts, and some added renal altitude can be managed with abatement of the kidney, or nephrectomy. If renal function, abstinent by glomerular filtration rate, is agilely poor, dialysis and kidney transplantation may be analysis options. Although they are not acutely harmful, annex stones can be a affliction and a nuisance. The abatement of annex stones includes complete beachcomber treatment, which break up the stones into abate pieces which are afresh anesthetized through the urinary tract. One accepted affirmation of annex stones is a aciculate affliction in the medial/lateral segments of the lower back.
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Anatomy
Location
In humans, the kidneys are amid in the abdominal cavity, in a amplitude alleged the retroperitoneum. There are two, one on anniversary ancillary of the spine; they are about at the vertebral akin T12 to L3.2 The appropriate annex sits just below the diaphragm and after to the liver, the larboard below the diaphragm and after to the spleen. Resting on top of anniversary annex is an adrenal gland. The aberration aural the belly atrium acquired by the alarmist about after-effects in the appropriate annex getting hardly lower than the left, and larboard annex getting amid hardly added centermost than the right.34 The top (cranial) locations of the kidneys are partially adequate by the eleventh and twelfth ribs, and anniversary able annex and adrenal gland are amidst by two layers of fat (the perirenal and pararenal fat) and the renal fascia. Anniversary developed annex weighs amid 125 and 170 grams in males and amid 115 and 155 grams in females.2 The larboard annex is about hardly beyond than the right.5
Structure
The annex has a bean-shaped structure, anniversary annex has biconcave and arched surfaces. The biconcave surface, the renal hilum, is the point at which the renal artery enters the organ, and the renal vein and ureter leave. The annex is amidst by boxy coarse tissue, the renal capsule, which is itself amidst by perinephric fat, renal fascia (of Gerota) and paranephric fat. The antecedent (front) bound of these tissues is the peritoneum, while the after (rear) bound is the transversalis fascia.
The above bound of the appropriate annex is adjoining to the liver; and the spleen, for the larboard border. Therefore, both move down on inhalation.
The annex is about 11–14 cm in length, 6 cm avant-garde and 3 cm thick.
The substance, or parenchyma, of the annex is disconnected into two above structures: credible is the renal cortex and abysmal is the renal medulla. Grossly, these structures yield the appearance of 8 to 18 cone-shaped renal lobes, anniversary absolute renal case surrounding a allocation of medulla alleged a renal pyramid (of Malpighi).2 Amid the renal pyramids are projections of case alleged renal columns (of Bertin). Nephrons, the urine-producing anatomic structures of the kidney, bulk the case and medulla. The antecedent clarification allocation of a nephron is the renal corpuscle, amid in the cortex, which is followed by a renal tubule that passes from the case abysmal into the medullary pyramids. Allotment of the renal cortex, a medullary ray is a accumulating of renal tubules that cesspool into a alone collecting duct.
The tip, or papilla, of anniversary pyramid empties urine into a minor calyx, accessory calyces abandoned into major calyces, and above calyces abandoned into the renal pelvis, which becomes the ureter.
Blood supply
The kidneys accept claret from the renal arteries, larboard and right, which annex anon from the abdominal aorta. Despite their almost baby size, the kidneys accept about 20% of the cardiac output.2
Each renal avenue branches into segmental arteries, adding added into interlobar arteries which access the renal abridged and extend through the renal columns amid the renal pyramids. The interlobar arteries afresh accumulation claret to the arcuate arteries that run through the abuttals of the case and the medulla. Anniversary arcuate avenue food several interlobular arteries that augment into the afferent arterioles that accumulation the glomeruli.
The interstitum (or interstitium) is the anatomic amplitude in the annex below the alone filters (glomeruli) which are affluent in blood vessels. The interstitum absorbs aqueous recovered from urine. Assorted altitude can advance to scarring and congestion of this area, which can could could cause annex dysfunction and failure.
After filtration occurs the claret moves through a baby arrangement of venules that assemble into interlobular veins. As with the arteriole administration the veins chase the aforementioned pattern, the interlobular accommodate claret to the arcuate veins afresh aback to the interlobar veins which appear to analysis the renal attitude departure the annex for admixture for blood.
Histology
Renal histology studies the analysis of the annex as beheld beneath a microscope. Assorted audible cell types action in the kidney, including:
- Kidney glomerulus parietal cell
- Kidney glomerulus podocyte
- Kidney adjacent tubule besom bound cell
- Loop of Henle attenuate articulation cell
- Thick ascendance limb cell
- Kidney distal tubule cell
- Kidney accession aqueduct cell
- Interstitial annex cell
Innervation
The annex and nervous system acquaint via the renal plexus, whose fibers advance forth the renal arteries to ability the kidney.6 Ascribe from the sympathetic afraid system triggers vasoconstriction in the kidney, thereby abbreviation renal claret flow.6 The annex is not anticipation to accept ascribe from the parasympathetic afraid system.6 Sensory ascribe from the annex campaign to the T10-11 levels of the spinal cord and is sensed in the agnate dermatome.6 Thus, affliction in the abut arena may be referred from the kidney.6
Functions
The annex participates in whole-body homeostasis, acclimation acid-base balance, electrolyte concentrations, extracellular aqueous volume, and adjustment of blood pressure. The annex accomplishes these homeostatic functions both apart and in concert with added organs, decidedly those of the endocrine system. Assorted endocrine hormones alike these endocrine functions; these cover renin, angiotensin II, aldosterone, antidiuretic hormone, and atrial natriuretic peptide, a allotment of others.
Many of the kidney's functions are able by almost simple mechanisms of filtration, reabsorption, and secretion, which yield abode in the nephron. Filtration, which takes abode at the renal corpuscle, is the action by which beef and ample proteins are filtered from the claret to accomplish an ultrafiltrate that will eventually become urine. The annex generates 180 liters of clarify a day, while reabsorbing a ample percentage, acceptance for alone the bearing of about 2 liters of urine. Reabsorption is the carriage of molecules from this ultrafiltrate and into the blood. Beard is the about-face process, in which molecules are transported in the adverse direction, from the claret into the urine.
Excretion of wastes
The kidneys defecate a array of decay articles produced by metabolism. These cover the nitrogenous wastes urea, from protein catabolism, and uric acid, from nucleic acid metabolism.
Acid-base homeostasis
Two agency systems, the kidneys and lungs, advance acid-base homeostasis, which is the aliment of pH about a almost abiding value. The kidneys accord to acid-base homeostasis by acclimation bicarbonate (HCO3-) concentration.
Osmolality regulation
Any cogent acceleration or bead in plasma osmolality is detected by the hypothalamus, which communicates anon with the posterior pituitary gland. An access in osmolality causes the gland to bury antidiuretic hormone (ADH), consistent in baptize reabsorption by the annex and an access in urine concentration. The two factors plan calm to acknowledgment the claret osmolality to its accustomed levels.
ADH binds to arch beef in the accession aqueduct that translocate aquaporins to the film acceptance baptize to leave the frequently closed film and be reabsorbed into the physique by the vasa recta, appropriately accretion the claret aggregate of the body.
There are two systems that actualize a hyperosmotic medulla and appropriately access the physique claret volume: Urea recycling and the 'single effect.'
Urea is usually excreted as a decay artefact from the kidneys. However, if claret claret aggregate is low and ADH is appear the aquaporins that are opened are aswell absorbent to urea. This allows urea to leave the accession aqueduct into the medulla creating a hyperosmotic band-aid that 'attracts' water. Urea can afresh re-enter the nephron and be excreted or recycled afresh depending on whether ADH is still present or not.
The 'Single effect' describes the actuality that the ascendance blubbery limb of the bend of Henle is not absorbent to baptize but is absorbent to NaCl. This agency that a countercurrent arrangement is created whereby the medulla becomes added concentrated ambience up an osmotic acclivity for baptize to chase should the aquaporins of the accession aqueduct be opened by ADH.
Blood burden regulation
Long-term adjustment of blood pressure predominantly depends aloft the kidney. This primarily occurs through aliment of the extracellular fluid compartment, the admeasurement of which depends on the claret sodium concentration. Although the annex cannot anon faculty claret pressure, changes in the supply of sodium and chloride to the distal allotment of the nephron adapt the kidney's beard of the agitator renin. If the extracellular aqueous alcove is broadcast and claret burden is high, the supply of these ions is added and renin beard is decreased. Similarly, if the extracellular aqueous alcove is apprenticed and claret burden is low, sodium and chloride supply is decreased and renin beard is added in response.
Renin is the aboriginal in a alternation of important actinic messengers that comprise the renin-angiotensin system. Changes in renin ultimately adapt the achievement of this system, principally the hormones angiotensin II and aldosterone. Anniversary hormone acts via assorted mechanisms, but both access the kidney's assimilation of sodium chloride, thereby accretion the extracellular aqueous alcove and adopting claret pressure. If renin levels are elevated, the concentrations of angiotensin II and aldosterone increase, arch to added sodium chloride reabsorption, amplification of the extracellular aqueous compartment, and an access in claret pressure. Conversely, if renin levels are low, angiotensin II and aldosterone levels decrease, application the extracellular aqueous compartment, and abbreviating claret pressure.
Hormone secretion
The kidneys bury a array of hormones, including erythropoietin, calcitriol, and renin. Erythropoietin is appear in acknowledgment to hypoxia (low levels of oxygen at tissue level) in the renal circulation. It stimulates erythropoiesis (production of red claret cells) in the bone marrow. Calcitriol, the activated analysis of vitamin D, promotes abdominal assimilation of calcium and the renal reabsorption of phosphate. Allotment of the renin-angiotensin-aldosterone system, renin is an agitator circuitous in the adjustment of aldosterone levels.
Development
The beastly annex develops from intermediate mesoderm. Kidney development, aswell alleged nephrogenesis, gain through a alternation of three alternating phases, anniversary credible by the development of a added avant-garde brace of kidneys: the pronephros, mesonephros, and metanephros.7
Evolutionary adaptation
Kidneys of assorted animals appearance affirmation of evolutionary adaptation and accept continued been advised in ecophysiology and comparative physiology. Annex morphology, generally indexed as the about medullary thickness, is associated with abode aridity a allotment of breed of mammals.8
Etymology
Medical agreement accompanying to the kidneys frequently use agreement such as renal and the prefix nephro-. The adjective renal, acceptation accompanying to the kidney, is from the Latin rēnēs, acceptation kidneys; the prefix nephro- is from the Ancient Greek chat for kidney, nephros (νεφρός).9 For example, surgical abatement of the annex is a nephrectomy, while a abridgement in annex action is alleged renal dysfunction.
Diseases and disorders
Congenital
- Congenital hydronephrosis
- Congenital obstruction of urinary tract
- Duplicated ureter occurs in about one in 100 reside births
- Horseshoe kidney occurs in about one in 400 reside births
- Polycystic annex disease
- Autosomal ascendant polycystic annex disease afflicts patients after in life. About one in 1000 bodies will advance this condition
- Autosomal backward polycystic annex disease is far beneath common, but added severe, than the ascendant condition. It is credible in utero or at birth.
- Renal agenesis. Abortion of one annex to analysis occurs in about one in 750 reside births. Abortion of both kidneys to analysis is consistently fatal.
- Renal dysplasia
- Unilateral baby kidney
- Multicystic dysplastic kidney occurs in about one in every 2400 reside births
Acquired
- Diabetic nephropathy
- Glomerulonephritis
- Hydronephrosis is the amplification of one or both of the kidneys acquired by obstruction of the breeze of urine.
- Interstitial nephritis
- Kidney stones (nephrolithiasis) are a almost accepted and decidedly aching disorder.
- Kidney tumors
- Lupus nephritis
- Minimal change disease
- In nephrotic syndrome, the glomerulus has been damaged so that a ample bulk of protein in the claret enters the urine. Added common appearance of the nephrotic affection cover swelling, low serum albumin, and top cholesterol.
- Pyelonephritis is infection of the kidneys and is frequently acquired by aggravation of a urinary amplitude infection.
- Renal failure
Kidney failure
Generally, bodies can reside frequently with just one kidney, as one has added activity renal tissue than is bare to survive. Alone if the bulk of activity annex tissue is abundantly beneath will chronic annex disease develop. Renal backup therapy, in the analysis of dialysis or kidney transplantation, is adumbrated if the glomerular filtration rate has collapsed actual low or if the renal dysfunction leads to astringent symptoms.
In added animals
In the majority of vertebrates, the mesonephros persists into the adult, admitting usually alloyed with the added avant-garde metanephros; alone in amniotes is the mesonephros belted to the embryo. The kidneys of fish and amphibians are about narrow, continued organs, application a cogent allocation of the trunk. The accession ducts from anniversary array of nephrons usually cesspool into an archinephric duct, which is homologous with the vas deferens of amniotes. However, the bearings is not consistently so simple; in cartilaginous fish and some amphibians, there is aswell a beneath duct, agnate to the amniote ureter, which drains the after (metanephric) locations of the kidney, and joins with the archinephric aqueduct at the bladder or cloaca. Indeed, in abounding cartilaginous fish, the antecedent allocation of the annex may base or cease to action altogether in the adult.10
In the a lot of archaic vertebrates, the hagfish and lampreys, the annex is almighty simple: it consists of a row of nephrons, anniversary elimination anon into the archinephric duct. Invertebrates may acquire excretory organs that are sometimes referred to as "kidneys", but, even in Amphioxus, these are never akin with the kidneys of vertebrates, and are added accurately referred to by added names, such as nephridia.10
The kidneys of reptiles abide of a amount of lobules abiding in a broadly beeline pattern. Anniversary lobule contains a alone annex of the ureter in its centre, into which the accession ducts empty. Reptiles accept almost few nephrons compared with added amniotes of a agnate size, possibly because of their lower metabolic rate.10
Birds accept almost large, continued kidneys, anniversary of which is disconnected into three or added audible lobes. The lobes consists of several small, anyhow arranged, lobules, anniversary centred on a annex of the ureter. Birds accept baby glomeruli, but about alert as abounding nephrons as analogously sized mammals.10
The animal annex is adequately archetypal of that of mammals. Distinctive appearance of the beastly kidney, in allegory with that of added vertebrates, cover the attendance of the renal abdomen and renal pyramids, and of a acutely apparent case and medulla. The closing affection is due to the attendance of continued loops of Henle; these are abundant beneath in birds, and not absolutely present in added vertebrates (although the nephron generally has a abbreviate intermediate segment amid the bizarre tubules). It is alone in mammals that the annex takes on its classical "kidney" shape, although there are some exceptions, such as the multilobed reniculate kidneys of cetaceans.10
History
The Latin appellation renes is accompanying to the English chat "reins", a analogue for the kidneys in Shakespearean English (e.g. Merry Wives of Windsor 3.5), which was aswell the time the King James Version was translated. Kidneys were already bargain admired as the bench of the censor and reflection1112, and a amount of verses in the Bible (e.g. Ps. 7:9, Rev. 2:23) accompaniment that God searches out and inspects the kidneys, or "reins", of humans. Similarly, the Talmud (Berakhoth 61.a) states that one of the two kidneys counsels what is good, and the added evil.
Animal kidneys as food
The kidneys of animals can be cooked and eaten by bodies (along with added offal).
Kidneys are usually broiled or sautéed, but in added circuitous dishes they are broiled with a booze that will advance their flavor. In abounding affairs kidneys are accumulated with pieces of meat or liver, like in mixed grill or in Meurav Yerushalmi. A allotment of the a lot of accounted annex dishes, the British Steak and annex pie, the Swedish Hökarpanna (pork and annex stew), the French Rognons de veau booze moutarde (veal kidneys in mustard sauce) and the Spanish "Riñones al Jerez" (kidneys broiled in sherry sauce), deserve appropriate mention.13
See also
References
- ^ Cotran, RS S.; Kumar, Vinay; Fausto, Nelson; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic base of disease. St. Louis, MO: Elsevier Saunders. ISBN 0-7216-0187-1.
- ^ a b c d Walter F., PhD. Boron (2004). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3.
- ^ "Kidneys Location Stock Illustration". http://www.indexedvisuals.com/scripts/ivstock/pic.asp?id=118-100.
- ^ http://www.bioportfolio.com/indepth/Kidney.html
- ^ Glodny B, Unterholzner V, Taferner B, et al. (2009). "Normal annex admeasurement and its influencing factors - a 64-slice MDCT abstraction of 1.040 asymptomatic patients". BMC Urology 9: 19. doi:10.1186/1471-2490-9-19. PMID 20030823. PMC 2813848. http://www.biomedcentral.com/1471-2490/9/19.
- ^ a b c d e Bard, Johnathan; Vize, Peter D.; Woolf, Adrian S. (2003). The kidney: from accustomed development to complete disease. Boston: Academic Press. pp. 154. ISBN 0-12-722441-6. http://books.google.com/?id=ctOm-cPwo60C&pg=PA154.
- ^ Bruce M. Carlson (2004). Human Embryology and Developmental Biology (3rd ed.). Saint Louis: Mosby. ISBN 0-323-03649-X.
- ^ Al-kahtani, M. A.; C. Zuleta, E. Caviedes-Vidal, and T. Garland, Jr. (2004). "Kidney accumulation and about medullary array of rodents in affiliation to habitat, physique size, and phylogeny". Physiological and Biochemical Zoology 77 (3): 346–365. doi:10.1086/420941. PMID 15286910. http://www.biology.ucr.edu/people/faculty/Garland/Al-kahtaniEA2004.pdf.
- ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Analysis and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.
- ^ a b c d e Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 367–376. ISBN 0-03-910284-X.
- ^ The Patient as Person: Explorations in Medical Ethics p. 60 by Paul Ramsey, Margaret Farley, Albert Jonsen, William F. May (2002)
- ^ History of Nephrology 2 p. 235 by International Association for the History of Nephrology Congress, Garabed Eknoyan, Spyros G. Marketos, Natale G. De Santo - 1997; Reprint of American Journal of Nephrology; v. 14, no. 4-6, 1994.
- ^ Rognons dans les recettes (French)
External links
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Wikimedia Commons has media accompanying to: Kidney |
- The Annex Foundation of Canada
- electron diminutive images of the annex (Dr. Jastrow's EM-Atlas)
- European Renal Genome activity annex action tutorial
- Kidney Foundation of Canada annex ache information
- Renal Fellow Network: Analysis & Action of Added Animals' Kidneys
- Kidney Diseases
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