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==Introducción==
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==Introduction==
Los riñones son órganos pares (derecho e izquierdo) que residen en el abdomen dorsal. Su función es filtrar la sangre a través de los glomérulos para formar el filtrado. Dicho filtrado es, a continuación, reabsorbido a lo largo de las nefronas, hasta que quedan los componentes innecesarios para el organismo. Algunos componentes, que se normalmente se absorben en su totalidad a nivel renal, se pueden encontrar en el organismo en exceso, en estas ocasiones los túbulos son capaces de responder, reabsorbiendo menor cantidad de dichos componentes. De este modo el riñón juega un papel importante en la homeostasis del organismo. También son capaces de interpretar el grado de hidratación del animal, excretando mayor o menos cantidad de agua según las necesidades.  
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The kidneys are paired organs which reside in the dorsal abdomen. One on the left and one on the right.  Their role is to filter the blood through the glomerulus to form what is known as the filtrate. This filtrate is then on the whole reabsorbed along the nephron until what is left comprises compounds superfluous to the requirements of the organism. Some compounds, normally fully reabsorbed, are on occasion present in the body in excess.  The kidney tubules are able to respond to this excess and excrete such compounds in greater amounts.  This is how the kidneys play a major role in the homeostasis of the organism. The kidneys also plays a vital role in the total water balance of the organism. Varying their excretion of water in relation to the hydration status of the animal.
  
Los riñones reciben el 25% del '''gasto cardíaco'''.  De éste filtran el 20% del plasma, formando el filtrado, del cual se reabsorbe todo excepto el 1%. Esto supone que todo el volumen sanguíneo es filtrado y reabsorbido cada 30 minutos. En este caso, los riñones se encargan de mantener el volumen y la composición del plasma, regulan la cantidad de agua, así como los niveles de iones y pH, retienen nutrientes y excretan desechos, toxinas y excesos de electrolitos. Realizan dichas funciones vía filtración glomerular, reabsorción de solutos, secreción tubular, balance hídrico y regulación ácido-base.
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The kidneys receive 25% of the '''cardiac output'''.  From this they filter 20% of the plasma forming a filtrate of which all but 1% is reabsorbed. This equates to all the circulatory volume being filtered and reabsorbed every 30 minutes. The functions of the kidneys are to maintain the volume and composition of plasma, regulate water, ion and pH levels, retain nutrients and excrete waste, toxins and excess electrolytes. The kidneys achieve these functions via; glomerular filtration, solute reabsorption, tubular secretion, water balance and acid-base regulation.
 
[[Image:sagkidlabelled.jpg|right|thumb|250px|<small><center>A labelled saggital section of a lamb kidney(Courtesy of Donal McNally - University of Nottingham)</center></small>]]
 
[[Image:sagkidlabelled.jpg|right|thumb|250px|<small><center>A labelled saggital section of a lamb kidney(Courtesy of Donal McNally - University of Nottingham)</center></small>]]
==Anatomía Común==
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==Common Anatomy==
 
[[Image:basicnormkidap.jpg|right|thumb|250px|<small><center>Histology section of a normal kidney (© RVC 2008)</center></small>]]
 
[[Image:basicnormkidap.jpg|right|thumb|250px|<small><center>Histology section of a normal kidney (© RVC 2008)</center></small>]]
 
[[Image:normkidcortap.jpg|right|thumb|250px|<small><center>Histology section of a normal renal cortex (© RVC 2008)</center></small>]]
 
[[Image:normkidcortap.jpg|right|thumb|250px|<small><center>Histology section of a normal renal cortex (© RVC 2008)</center></small>]]
 
[[Image:promaledogab.jpg|right|thumb|250px|<small><center>A prosection of the abdomen of a male dog (© UoN 2008)</center></small>]]
 
[[Image:promaledogab.jpg|right|thumb|250px|<small><center>A prosection of the abdomen of a male dog (© UoN 2008)</center></small>]]
 
[[Image:profemaledogab.jpg|right|thumb|250px|<small><center>A prosection of the abdomen of a female dog(© UoN 2008)</center></small>]]
 
[[Image:profemaledogab.jpg|right|thumb|250px|<small><center>A prosection of the abdomen of a female dog(© UoN 2008)</center></small>]]
* Los riñones son parte del tracto urinario, donde la sangre es filtrada produciendo la orina.
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* The kidney is the part of the urinary tract where blood is filtered and urine is produced.  
*Son pares y se encuentran en posición retroperitoneal.   
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* The kidneys are paired and lie in a retroperitoneal position.   
*Situados en la región caudo-dorsal del abdomen.
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* They are positioned in the caudo-dorsal abdomen.
*Descansan en una hendidura de la fascia sublumbar. Normalmente con abundante grasa que recubre y protege a los riñones de la presión de otros órganos.
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* They lie within a splitting of the sublumbar fascia. This also often contains a large quantity of fat to cushion and protect the kidneys from the pressure of other organs 
*El riñón derecho es más craneal que el izquierdo, excepto en el cerdo.
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* The right kidney is most cranial in all species except the pig.
*En las especies en las que el riñón derecho es más craneal, éste se encuentra en la fosa renal del lóbulo caudado del hígado.
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* In species where the right kidney is most cranial it lies in a small fossa of the caudate liver lobe.
*Asimismo el riñón izquierdo es más móvil.
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* However the left kidney is the most mobile.
*En los primeros estadios del desarrollo todos los animales tienen un riñón multi-lobulado, pero conforme se van desarrollando van adquiriendo las características típicas de la especie.
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* During development all species begin with a multi-lobed structure but a varying degree of fusion occurs between the species giving rise to the various different characteristics seen.
  
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==The Basic Components of the Kidney==
  
==Componentes Básicos del Riñón==
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===Outer fibrous capsule===
  
===Cápsula Fibrosa Externa===
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A tough outer capsule surrounds the parenchyma and this prevents the kidney expanding.  It is easily stripped away from a healthy kidney but adheres where pathology has occured.
  
Una gruesa cápsula recubre el parénquima previniendo la expansión del riñón. Se separa fácilmente en un riñón sano, pero se adhiere al parénquima en caso de patologías.
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===Renal Cortex===
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* 2 Parts
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* External zone
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* Internal zone (juxtamedullar)
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* Contains the following parts of the [[:Category:Nephron| nephron]]
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** [[Nephron Microscopic Anatomy #The Renal Corpuscle| Renal corpuscle]]
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** [[Nephron Microscopic Anatomy #Proximal Tubule| Proximal convoluted tubule]]
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** [[Nephron Microscopic Anatomy #The Distal Tubule| Distal convoluted tubule]]
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** [[WikiWords#Urinary Section| Medullary Rays]]
  
===Corteza Renal===
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===Renal Medulla===
*2 Partes
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* Contains medullary pyramids
*Zona externa
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* The part nearest the cortex is the base of the pyramid which narrows to form the inner part - renal papilla
*Zona interna (yuxtaglomerular)
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* The medulla can be split into two parts, the outer and the inner
*Contiene las siguientes partes de la [[:Categoría:Nefrona|nefrona]]
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* Different parts of the [[:Category:Nephron| nephron]] reside in these areas
** [[Nephron Microscopic Anatomy #Corpúsculo Renal|Corpúsculo renal]]
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====Outer Medulla====
** [[Nephron Microscopic Anatomy #Túbulo Contorneado Proximal|Túbulo contorneado proximal]]
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The outer medulla can be further divided into the outer and inner stripe
** [[Nephron Microscopic Anatomy #Túbulo Contorneado Distal|Túbulo contorneado distal]]
 
** [[WikiWords#Sección Urinario|Rayos Medulares]]
 
  
===Médula Renal===
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=====The Outer Stripe=====
*Contiene las pirámides medulares
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This section located just inside the cortex contains the following parts of the [[:Category:Nephron| nephron]]:
*La parte más próxima a la corteza es la base de la pirámide, que se estrecha para formar la parte interna -papila renal
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* [[Nephron Microscopic Anatomy #Proximal Tubule| Proximal straight tubules]]
*La médula se puede dividir en dos partes, la externa y la interna
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* [[Nephron Microscopic Anatomy #The Distal Tubule| Distal straight tubules]]
*Encontraremos diferentes partes de la [[:Categoría:Nefrona|nefrona]] en dichas áreas.
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* [[Nephron Microscopic Anatomy #The Loop of Henle| Thin descending and thick ascending limbs of the loop of henle]]
====Médula Externa====
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* [[Nephron Microscopic Anatomy #Collecting Duct| Outer medullary collecting ducts]]
Se puede dividir, a su vez, en franja externa e interna.
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* [[Nephron Microscopic Anatomy  #The Vasa Recta| Vasa recta]]
  
=====Franja Externa=====
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=====The Inner Stripe=====
Esta sección se encuentra adyacente a la corteza y contiene las siguientes partes de la [[:Categoría:Nefrona|nefrona]]:
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Located inside of the outer stripe this section contains the following parts:
* [[Nephron Microscopic Anatomy#Túbulos Rectos Proximales|Túbulos rectos proximales ]]
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* [[Nephron Microscopic Anatomy #The Loop of Henle| Thin ascending and thick ascending limbs of the loop of henle]]
* [[Nephron Microscopic Anatomy#Túbulos Rectos Distales|Túbulos rectos distales]]
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* [[Nephron Microscopic Anatomy #Collecting Duct| Outer medullary collecting ducts]]
* [[Nephron Microscopic Anatomy#Asa de Henle|Porción delgada descendiente y porción gruesa ascendiente del Asa de Henle]]
 
* [[Nephron Microscopic Anatomy#Túbulos Colectores|Túbulos colectores]]
 
* [[Nephron Microscopic Anatomy#Vasa Recta|Vasa recta]]
 
  
=====Franja Interna=====
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=====The Difference=====
Adyacente a la franja externa, esta sección contiene:
 
* [[Nephron Microscopic Anatomy #Asa de Henle|Porción delgada ascendente y porción gruesa descendiente del Asa de Henle]]
 
* [[Nephron Microscopic Anatomy#Túbulos Colectores|Túbulos colectores]]
 
  
=====Diferencias=====
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The outer stripe contains the straight proximal tubules and the inner does not.  However the inner contains thin ascending limbs and the outer does not.  This difference makes up the anatomical demarcation between the two stripes
  
La franja externa contiene los túbulos rectos proximales y la franja interna no. Asimismo la franja interna contiene las porciones delgadas ascendentes y la externa no. La diferencia pone de manifiesto la demarcación anatómica entre ambas.
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====Inner Medulla====
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* The inner medulla however only contains the following parts:
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** [[Nephron Microscopic Anatomy #The Loop of Henle| Loop of henle]]
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** [[Nephron Microscopic Anatomy #Collecting Duct| Collecting ducts]]
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** [[Nephron Microscopic Anatomy  #The Vasa Recta| Vasa recta]]
  
====Médula Interna====
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===Renal Pelvis===
* La medulla interna solo contiene las siguientes partes:
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* The renal sinus is located within an indentation on the medial side of the kidney
** [[Nephron Microscopic Anatomy#Asa de Henle|Asa de Henle]]
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* The renal pelvis is located within the renal sinus
** [[Nephron Microscopic Anatomy#Túbulos Colectores|Túbulos colectores]]
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* All papillary ducts open here
** [[Nephron Microscopic Anatomy #Vasa Recta|Vasa recta]]
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* The renal pelvis then drains into the ureters
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* The renal pelvis is lined with transitional epithelium
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* Varies between species
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* Absent in cow
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* Contains mucous glands in the horse
  
===Pelvis Renal===
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===Divisions of the Kidney===
*El seno renal se localiza en hendidura que deja la cara medial del riñón
 
*En él se encuentra la pelvis renal
 
*A ésta llegan todos los túbulos renales
 
*A continuación la pelvis drena  la orina a los uréteres
 
*La pelvis renal está cubierta con epitelio de transición
 
*Varía entre especies
 
*No se encuentra en bóvidos
 
*Contiene glándulas mucosas en équidos
 
  
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* The kidney is divided into [[WikiWords#Urinary Section| renal lobes]] from a structural point of view.
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* These can then be divided into a renal pyramid and the piece of cortex above it
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* Renal Pyramids are important descriptor of part of the kidney.
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**These structures are visible grossly and are the region of the medulla which appears triangular in cross section. They are actually cone shaped and the pointed part which faces towards the renal pelvis is termed the apex and the part against the cortex the base.
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* They can also be subdivided into [[WikiWords#Urinary Section| renal lobules]] comprising of [[:Category:Nephron| nephrons]], [[WikiWords#Urinary Section| a medullary ray]] and [[Nephron Microscopic Anatomy #Collecting Duct| a collecting duct]].
  
===Divisiones del Riñón===
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* In some species the kidneys are described as '''multipyramidal''' this means they have multiple lobes and pyramids.  Others are described as '''unipyramidal''' meaning they only have one lobe and pyramid.
  
* El riñón está dividido en dos [[WikiWords#Sección Urinario|lóbulos renales]] desde un punto de vista morfológico.
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===Innervation===
*Éstos pueden dividirse en una pirámide renal y una parte de corteza sobre ella
 
*Las pirámides renales son una parte importante del riñón.
 
**Son visibles macroscópicamente y se presentan como estructuras triangulares en la médula renal. La parte más estrecha apunta hacia la pelvis renal y se denomina ápex, mientras que la zona en contacto con la corteza se denomina base.
 
*También pueden encontrarse subdivididos en [[WikiWords#Sección Urinario|lóbulos renales]], que contienen [[:Categoría:Nefronas|nefronas]], un [[WikiWords#Sección Urinario|rayo medullar]] y un [[Nephron Microscopic Anatomy #Túbulo Colector|túbulo colector]].
 
  
*En algunas especies el riñón se describe como '''multipiramidal''', esto quiere decir que tiene varios lóbulos y pirámides. Otros se describen como '''unipirámidales''', es decir, con un solo lóbulo y pirámide.
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* Sympathetic and parasympathetic fibres from solar plexus
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* Travel with renal arteries
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* Sympathetic fibres synapse in coeliac ganglion and cranial mesenteric ganglion
  
===Inervación===
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===Lymphatic Drainage===
  
*Fibras simpáticas y parasimpáticas del plexo solar o celíaco.
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Renal lymph nodes
*Viajan junto a las arterias.
 
*Fibras simpáticas hacen sinapsis en el ganglio celíaco y en el ganglio mesentérico craneal.
 
  
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==Anatomical Species Differences==
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[[Image:lambpigkidcombDM.jpg|right|thumb|250px|<small><center>A picture showing a typical lamb and pig kidney. (Courtesy of Donal McNally - University of Nottingham</center></small>]]
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The various species have major and rather striking differences in the structure of their kidneys.
  
===Drenaje Linfático===
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===Canine, Feline, and Ovine===
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These species all have similar renal anatomy. Their kidneys are relatively short and thick and they are the traditional kidney bean shape. They have a smooth outer surface and have a single renal papilla.  The renal pelvis is large and irregular with recesses which are finger like processes.
  
Nódulos Linfáticos Renales
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The kidney of the feline is relatively bigger than the other species and is quite distinctive because the sub-capsular veins which run towards the hilum are visible. The size of the kidney can be estimated by palpation or via imaging. On a ventrodorsal radiograph, normal kidney size is usually between two to three times the length of second lumbar vertebra, 3 - 4.5 centimetres.
  
==Diferencias Anatómicas Entre Especies==
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===Bovine===
[[Image:lambpigkidcombDM.jpg|right|thumb|250px|<small><center>Imagen que muestra el riñón típico de un cordero y de un cerdo.  (Courtesy of Donal McNally - University of Nottingham</center></small>]]
 
Podemos encontrar diferencias importantes entre las especies domésticas.
 
  
===Caninos, Felinos y Ovinos===
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The kidneys of the bovine do not lose their foetal lobulation.  In fact the surface of each kidney is divided into approximately 12 lobules.    The right kidney is flattened and ellipsoidal where as the left kidney is thicker at the caudal end than the cranial. Each kidney is surrounded by the capsula adiposa; a layer of fat. Despite what it’s externally lobulated appearance may suggest the cortex of the bovine kidney is continuous and the kidney is of multipyramidal type. The bovine kidney has no renal pelvis but rather the [[Ureters - Anatomy & Physiology | Ureters]] enters the kidney and divide into a cranial and caudal branch.  These branches then subdivide and the papilla at the apex of the pyramids open and drain into these.
Todos ellos tienen una anatomía renal similar. Los riñones son cortos y gruesos y tienen la típica forma de judía. Tienen una superficie lisa y una única papila. La pelvis renal es grande e irregular, con recesos digitiformes.
 
  
El riñón de los felinos es relativamente mayor que el de otras especies y sus venas subcapsulares son visibles macroscópicamente.
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The right ureter leaves the kidney and passes along the roof of the abdomen to the pelvis in a fairly standard pattern. The left ureter however moves across the dorsal surface of its kidney to return to the midline and follow a course as if the kidney was located on the left.  (both kidneys in the bovine are located on the right see the anatomical landmarks section for further details)
  
The size of the kidney can be estimated by palpation or via imaging. On a ventrodorsal radiograph, normal kidney size is usually between two to three times the length of second lumbar vertebra, 3 - 4.5 centimetres.
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===Porcine===
  
===Bovino===
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The kidneys are dorsoventrally flattened.  The renal pelvis opens into quite a large space of two major calicyes from which bud about 10 minor calyces.  These attach to one renal papillae each.  The kidneys have a smooth surface.
  
Los riñones del Ganado bovino no pierden su lobulación fetal. De hecho la superficie de cada riñón está dividido en 12 lóbulos aproximadamente. El riñón derecho es plano y elipsoidal, mientras que el izquierdo es más grueso en la cara caudal que en la craneal. Cada riñón está rodeado por una capa de tejido adiposo. A pesar de lo que podríamos pensar por  su superficie lobulada, la corteza del riñón es continua y el riñón es de tipo multipiramidal. El riñón bovino no tiene pelvis renal pero los [[Uréteres - Anatomía & Fisiología| uréteres]] entran al riñón y dan una rama caudal y otra craneal. Estas ramas, a continuación se subdividen para recibir el contenido de la papila.
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===Equine===
  
El uréter derecho abandona el riñón y recorre el techo del abdomen hacia la pelvis. El uréter izquierdo, en cambio, recorre la superficie dorsal del riñón, retorna a la línea media y sigue su recorrido como si se encontrara en el lado izquierdo (en bóvidos ambos riñones se encuentran en el lado derecho, para más detalles ver localización anatómica).
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The equine kidneys not only have very different shapes compared to the rest of the domestic species but they also each have a different shape.  The right kidney is described as heart shaped whilst the left is described as being pyramidal.  Each organ weighs approximately 700g and both are dorsoventrally flattened.  The kidneys are basically unipyramidal and the only demarcation between what were the multiple pyramids of the foetus are the interlobar arteries.  This is not always the case in the foal where it is common to be able to identify lobes and the external surface is not always smooth. The horse has a single renal papilla like the dog and its renal pelvis is large and irregular with 2 recesses (finger like processes). The cells of its pelvis secret mucin giving the urine its cloudy appearance.
  
===Porcino===
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==Anatomical Landmarks==
  
Los riñones son aplanados dorsoventralmente. La pelvis renal se abre a dos cálices mayores, de los cuales brotan unos 10 cálices menores. Éstos se adhieren a una papila renal cada uno. Los riñones tienen una superficie lisa.
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Each species has a slightly different orientation of the kidneys within the abdomen.
  
===Equino===
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===Carnivores===
  
Los riñones de los équidos tienen una morfología muy distinta al resto de animales domésticos. El riñón derecho podemos decir que tiene forma de corazón, mientras que el izquierdo se describe como piramidal. Cada uno pesa aproximadamente 700g y ambos están aplanados dorsoventralmente. Son básicamente unipiramidales y la única demarcación que queda de su morfología fetal son las arterias interlobulares. En estadíos fetales se pueden identificar los lóbulos externamente y la superficie externa no siempre es lisa. El caballo tiene una única papila y su pelvis es grande e irregular con dos recesos digitiformes. Las células de la pelvis secretan mucina dándole una apariencia turbia a la orina.  
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The kidneys in these species are very mobile. Especially the left one and especially in the feline.  These anatomical landmarks describe the most common locations. The right kidney is more cranial than the left and tends to lie beneath L1 - L3 where as the left tends to lie under L2-L4. The reason the right kidney is less mobile than the left is that it tends to be almost entirely enclosed within the renal fossa of the caudate lobe of the [[Liver - Anatomy & Physiology|liver]]. The kidneys are enclosed within a layer of fat and this increases with the obesity of the animal.
  
==Localización Anatómica==
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Medially to the right kidney you will find the caudal vena cava and the right adrenal gland can be found dorsolateral to this structure but still medially to the kidney.  Ventrally can be found the Descending [[Duodenum - Anatomy & Physiology|duodenum]] with the right pancreatic limb more towards the ventromedial aspect.  In females the right ovary can be found caudoventrally.
  
Cada especie tiene una disposición ligeramente distinta de los riñones en el abdomen.
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The '''Cranial pole''' of the left kidney contacts the [[Monogastric Stomach - Anatomy & Physiology|greater curvature of stomach]] it also contacts the [[Spleen - Anatomy & Physiology|spleen]] on its dorsomedial aspect as well as potentially contacting the left limb of the pancreas.  The left adrenal gland can be found at the medial aspect of the cranial pole.  The '''Caudal pole''' of the left kidney contacts the [[Small Intestine Overview - Anatomy & Physiology|Small intestine]] and the Descending [[Colon - Anatomy & Physiology|colon]].  At its caudoventral aspect in females is found the left Ovary.
  
===Carnívoros===
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===Ruminants===
  
Los riñones en estas especies son muy móviles. Especialmente el izquierdo y sobretodo en los felinos.  
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Due to the rumen taking up most of the left side of the abdomen it is normal in the bovine to find both of the kidneys on the right side. In the ovine the kidneys are surrounded by very thick masses of fat which reduce the impact of the rumen on their location.  The kidneys in the living animal vary their position substantially with respiration and with the pressure of the other organs.
  
El riñón derecho es más craneal y tiende a situarse entre L1-L3, mientras que el izquierdo se sitúa entre L2-L4. La razón de que el derecho sea menos móvil es que se sitúa en la fosa renal del lóbulo caudado del [[Hígado - Anatomía & Fisiología|hígado]]. Además ambos riñones quedan cubiertos por una capa de grasa, muy aumentada en animales obesos.
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The right kidney has a retroperitoneal attachment to the "sublumbar" musculature.  Cranially it touches the liver. In the dead specimen the right kidney occupies the region between the last rib and somewhere between the 2nd and 3rd lumbar vertebrae’s transverse process. The right kidney usually contacts pancreas, duodenum, adrenal glands and colon as well as the afore mentioned liver.
  
Medialmente al riñón derecho encontramos la vena cava caudal, la glándula adrenal derecha podemos encontrarla dorsolateralmente a ésta y medialmente al riñón. Ventralmente hallamos el [[Duodeno - Anatomía & Fisiología|duodeno]] descendiente, con el lóbulo pancreático derecho en la cara ventromedial. En hembras también podemos observar el ovario derecho caudoventralmente.
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The left kidney in the bovine is to be found caudoventrally to the right one usually in the region between the 2nd and 4th lumbar vertebrae
  
El '''polo craneal''' del riñón izquierdo contacta con la [[Estómago Monogástrico - Anatomía & Fisiología|curvatura mayor del estómago]], así como con el [[Bazo - Anatomía & Fisiología|bazo]]y lóbulo izquierdo del páncreas, en su cara dorsomedial. La glándula adrenal izquierda la encontramos en la cara medial del polo craneal. El '''polo caudal''' del riñón izquierdo contacta con el [[Intestino Delgado - Resumen - Anatomía & Fisiología|intestino delgado]] y el [[Colon - Anatomía & Fisiología|colon]] descendente.  En su cara caudoventral, en hembras, se encuentra el ovario izquierdo.
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===Porcine===
  
===Rumiantes===
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The left and right kidneys are more or less aligned in the pig unlike other species. The kidneys of the pig are embedded in lots of fat and lie against the psoas muscle.  They span the distance between the last rib cranially and the 4th lumber vertebrae caudally.  The '''right kidney''' does not touch the liver unlike other species and is related ventrally to the descending duodenum and jejunum.  The '''left kidney''' is ventrally related to the ascending colon, the base of the caecum and the pancreas.
  
Debido al gran tamaño del rumen, situado en el lado izquierdo del abdomen, se ven desplazados todos los órganos de dicha cavidad hacia la derecha. Por tanto, encontramos en éste lado ambos riñones. En el caso del ovino se encuentran cubiertos por una gran cantidad de grasa que reduce el impacto del rumen sobre ellos. Los riñones, a su vez, pueden variar mucho de localización debido a los movimientos respiratorios y a la presión de otros órganos.
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===Equine===
  
El riñón derecho tiene una adherencia retroperitoneal a la musculatura "sublumbar"Cranealmente contacta con el hígado. En cadáveres ocupa la región entre la última costilla y la apófisis transversa de la  2ª-3ª vértebra lumbar. Asimismo contacta también con el páncreas, duodeno, glándula adrenal y colon.
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The kidneys of the horse are both enclosed in a fat capsuleDorsally they rest against the psoas muscle and against the diaphragm.
  
El riñón izquierdo en bovino se encuentra caudoventralmente al derecho y en la región entre la 2ª y 4ª vértebra lumbar.
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The right kidney is to be found ventrally to and between the last 2 ribs and first lumbar transverse process. Cranially it touches the liver and caudally it is attached to the pancreas and the base of caecum. The duodenum winds around its lateral and then ventral surfaces.  Medially is the caudal vena cava and adrenal gland.
  
===Porcino===
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The left kidney is between the last rib and 3rd transverse process.  Its ventral surface is almost completely covered by the peritoneum and contacts the small intestine and and small colon.  The spleen contacts it cranioventrally.  Medially is the left adrenal gland and aorta.
  
En porcino ambos riñones se encuentran más alineados. Están envueltos en mucha grasa y se encuentran junto al músculo psoas. Cubren la distancia desde la última costilla y la 4ª vértebra lumbar. El '''riñón derecho''' no llega a contactar con el hígado, como hace en el resto de especies, y se relaciona ventralmente al duodeno descendente y yeyuno. El '''riñón izquierdo''' se relaciona ventralmente con el colon ascendente, base del ciego y páncreas.
+
==Renal Blood Supply==
  
===Equino===
+
* Supplied by renal arteries
 +
* Arise from aorta
 +
* 3-4mm diameter - dog
 +
* Often divide into dorsal and ventral branches before entering kidney
 +
* Common to find double the normal number - dog
  
Los riñones del caballo están ambos envueltos en una cápsula grasa. Dorsalmente contactan con el músculo psoas y el diafragma.
+
===Left Renal Vessels===
  
El riñón derecho podemos hallarlo, ventralmente, entre las últimas 2 costillas y la primera apófisis transversa lumbar. Cranealmente se relaciona con el hígado y caudalmente está adherido al páncreas y a la base del ciego. El duodeno rodea sus caras lateral y ventral. Medialmente encontramos la vena cava caudal y la glándula adrenal.
+
* Left renal artery
 +
** Originates 2cm caudal to the right renal artery
 +
** ~3-4cm long - dog
  
El riñón izquierdo se encuentra entre la última costilla y la 3ª apófisis transversa lumbar. Su superficie ventral está cubierta, prácticamente en su totalidad, por peritoneo y contacta con el intestino delgado y el colon. El bazo contacta craneoventralmente y medialmente encontramos la glándula adrenal y la aorta.
+
* Left renal vein
 +
** Immediately ventral to artery
 +
** ~3-4cm long - dog
  
==Riego Sanguíneo==
+
===Right Renal Vessels===
  
*Llevado a cabo por las arterias renales
+
* Right Renal Artery
*Se ramifican de la aorta
+
** 2cm cranial to left renal artery
*3-4mm de diámetro en el perro
+
** 4 cm caudal to cranial mesenteric artery
*Se dividen en las ramas dorsal y ventral antes de entrar al riñón, normalmente
+
** Passes dorsal over the caudal vena cava
*Es frecuente encontrarlas duplicadas en el perro.
+
** ~4-5cm long - dog
  
 +
* Right Renal Vein
 +
** Ventral to artery
 +
** ~4-5cm long - dog
  
===Vasos del Riñón Izquierdo===
+
===Internal Vascularisation===
  
* Arteria renal izquierda
+
Once the renal artery enters the kidney is divides into the interlobar arteries.  These pass through the gaps between the renal pyramids as the reach the junctions between the cortex and medullar they branch into the arcuate arteries which move over the base of the pyramids.  From these come the interlobular arteries which supply the individual lobules of the cortex.  These arteries then branch many times to supply individual glomeruli.  The capillaries of the glomerulus then rejoin to form one vessel which then forms the [[Glomerular Apparatus and Filtration - Anatomy & Physiology#Pressure in the Peritubular Capillaries|peritubular capillaries]] of that nephron.  The interlobular arteries are examples of end arterioles and there are few anastomoses.  Obstruction of one of these arterioles causes ischaemic damage in the kidneys.  This is also potentially the case with the interlobar arteries.
**Se origina a 2cm caudalmente a la arteria renal izquierda
 
**~3-4cm de largo en el perro
 
  
  
* Vena renal izquierda
 
**Inmediatamente ventral a la arteria
 
**~3-4cm de largo en el perro
 
 
 
===Vasos del Riñón Derecho===
 
 
*Arteria renal derecha
 
**2cm cranealmente a la arteria renal derecha
 
**4 cm caudalmente a la arteria mesentérica craneal
 
**Pasa dorsalmente a la vena cava caudal
 
**~4-5cm de largo en el perro
 
 
 
* Vena renal derecha
 
**Ventral a la arteria
 
**~4-5cm de largo en el perro
 
 
 
===Vascularización Interna===
 
 
Una vez que la arteria entra en el riñón se divide en arterias interlobulares. Éstas pasan a través de huecos entre las pirámides renales para alcanzar la unión entre la corteza y la médula, a continuación se ramifican en arterias arqueadas que se mueven sobre la base de las pirámides. De éstas proceden las arterias interlobulares que riegan los lóbulos individuales de la corteza. A su vez, éstas se ramifican muchas veces para dar riego glomérulos individuales. Los capilares de los glomérulos, a continuación, se vuelven a unir para formar vasos que formarán los [[Aparato Glomerular Apparatus y la Filtración - Anatomía & Fisiología#Pressure in the Peritubular Capillaries|capilares peritubulares]] de la nefrona.  Las arterias interlobulares son ejemplos de arteriolas terminales y presentan anastomosis. La obstrucción de alguna de éstas causa daño isquémico a los riñones.
 
 
<br>
 
{{Translated
 
|por = '[[Usuario:Fa vet|Fanny Olsson]]'
 
|date = 16.09.2011
 
}}
 
  
 
[[Categoría:Riñón - Anatomía & Fisiología]]
 
[[Categoría:Riñón - Anatomía & Fisiología]]

Revisión del 17:09 30 oct 2011

Introduction

The kidneys are paired organs which reside in the dorsal abdomen. One on the left and one on the right. Their role is to filter the blood through the glomerulus to form what is known as the filtrate. This filtrate is then on the whole reabsorbed along the nephron until what is left comprises compounds superfluous to the requirements of the organism. Some compounds, normally fully reabsorbed, are on occasion present in the body in excess. The kidney tubules are able to respond to this excess and excrete such compounds in greater amounts. This is how the kidneys play a major role in the homeostasis of the organism. The kidneys also plays a vital role in the total water balance of the organism. Varying their excretion of water in relation to the hydration status of the animal.

The kidneys receive 25% of the cardiac output. From this they filter 20% of the plasma forming a filtrate of which all but 1% is reabsorbed. This equates to all the circulatory volume being filtered and reabsorbed every 30 minutes. The functions of the kidneys are to maintain the volume and composition of plasma, regulate water, ion and pH levels, retain nutrients and excrete waste, toxins and excess electrolytes. The kidneys achieve these functions via; glomerular filtration, solute reabsorption, tubular secretion, water balance and acid-base regulation.

A labelled saggital section of a lamb kidney(Courtesy of Donal McNally - University of Nottingham)

Common Anatomy

Histology section of a normal kidney (© RVC 2008)
Histology section of a normal renal cortex (© RVC 2008)
A prosection of the abdomen of a male dog (© UoN 2008)
A prosection of the abdomen of a female dog(© UoN 2008)
  • The kidney is the part of the urinary tract where blood is filtered and urine is produced.
  • The kidneys are paired and lie in a retroperitoneal position.
  • They are positioned in the caudo-dorsal abdomen.
  • They lie within a splitting of the sublumbar fascia. This also often contains a large quantity of fat to cushion and protect the kidneys from the pressure of other organs
  • The right kidney is most cranial in all species except the pig.
  • In species where the right kidney is most cranial it lies in a small fossa of the caudate liver lobe.
  • However the left kidney is the most mobile.
  • During development all species begin with a multi-lobed structure but a varying degree of fusion occurs between the species giving rise to the various different characteristics seen.

The Basic Components of the Kidney

Outer fibrous capsule

A tough outer capsule surrounds the parenchyma and this prevents the kidney expanding. It is easily stripped away from a healthy kidney but adheres where pathology has occured.

Renal Cortex

Renal Medulla

  • Contains medullary pyramids
  • The part nearest the cortex is the base of the pyramid which narrows to form the inner part - renal papilla
  • The medulla can be split into two parts, the outer and the inner
  • Different parts of the nephron reside in these areas

Outer Medulla

The outer medulla can be further divided into the outer and inner stripe

The Outer Stripe

This section located just inside the cortex contains the following parts of the nephron:

The Inner Stripe

Located inside of the outer stripe this section contains the following parts:

The Difference

The outer stripe contains the straight proximal tubules and the inner does not. However the inner contains thin ascending limbs and the outer does not. This difference makes up the anatomical demarcation between the two stripes

Inner Medulla

Renal Pelvis

  • The renal sinus is located within an indentation on the medial side of the kidney
  • The renal pelvis is located within the renal sinus
  • All papillary ducts open here
  • The renal pelvis then drains into the ureters
  • The renal pelvis is lined with transitional epithelium
  • Varies between species
  • Absent in cow
  • Contains mucous glands in the horse

Divisions of the Kidney

  • The kidney is divided into renal lobes from a structural point of view.
  • These can then be divided into a renal pyramid and the piece of cortex above it
  • Renal Pyramids are important descriptor of part of the kidney.
    • These structures are visible grossly and are the region of the medulla which appears triangular in cross section. They are actually cone shaped and the pointed part which faces towards the renal pelvis is termed the apex and the part against the cortex the base.
  • They can also be subdivided into renal lobules comprising of nephrons, a medullary ray and a collecting duct.
  • In some species the kidneys are described as multipyramidal this means they have multiple lobes and pyramids. Others are described as unipyramidal meaning they only have one lobe and pyramid.

Innervation

  • Sympathetic and parasympathetic fibres from solar plexus
  • Travel with renal arteries
  • Sympathetic fibres synapse in coeliac ganglion and cranial mesenteric ganglion

Lymphatic Drainage

Renal lymph nodes

Anatomical Species Differences

A picture showing a typical lamb and pig kidney. (Courtesy of Donal McNally - University of Nottingham

The various species have major and rather striking differences in the structure of their kidneys.

Canine, Feline, and Ovine

These species all have similar renal anatomy. Their kidneys are relatively short and thick and they are the traditional kidney bean shape. They have a smooth outer surface and have a single renal papilla. The renal pelvis is large and irregular with recesses which are finger like processes.

The kidney of the feline is relatively bigger than the other species and is quite distinctive because the sub-capsular veins which run towards the hilum are visible. The size of the kidney can be estimated by palpation or via imaging. On a ventrodorsal radiograph, normal kidney size is usually between two to three times the length of second lumbar vertebra, 3 - 4.5 centimetres.

Bovine

The kidneys of the bovine do not lose their foetal lobulation. In fact the surface of each kidney is divided into approximately 12 lobules. The right kidney is flattened and ellipsoidal where as the left kidney is thicker at the caudal end than the cranial. Each kidney is surrounded by the capsula adiposa; a layer of fat. Despite what it’s externally lobulated appearance may suggest the cortex of the bovine kidney is continuous and the kidney is of multipyramidal type. The bovine kidney has no renal pelvis but rather the Ureters enters the kidney and divide into a cranial and caudal branch. These branches then subdivide and the papilla at the apex of the pyramids open and drain into these.

The right ureter leaves the kidney and passes along the roof of the abdomen to the pelvis in a fairly standard pattern. The left ureter however moves across the dorsal surface of its kidney to return to the midline and follow a course as if the kidney was located on the left. (both kidneys in the bovine are located on the right see the anatomical landmarks section for further details)

Porcine

The kidneys are dorsoventrally flattened. The renal pelvis opens into quite a large space of two major calicyes from which bud about 10 minor calyces. These attach to one renal papillae each. The kidneys have a smooth surface.

Equine

The equine kidneys not only have very different shapes compared to the rest of the domestic species but they also each have a different shape. The right kidney is described as heart shaped whilst the left is described as being pyramidal. Each organ weighs approximately 700g and both are dorsoventrally flattened. The kidneys are basically unipyramidal and the only demarcation between what were the multiple pyramids of the foetus are the interlobar arteries. This is not always the case in the foal where it is common to be able to identify lobes and the external surface is not always smooth. The horse has a single renal papilla like the dog and its renal pelvis is large and irregular with 2 recesses (finger like processes). The cells of its pelvis secret mucin giving the urine its cloudy appearance.

Anatomical Landmarks

Each species has a slightly different orientation of the kidneys within the abdomen.

Carnivores

The kidneys in these species are very mobile. Especially the left one and especially in the feline. These anatomical landmarks describe the most common locations. The right kidney is more cranial than the left and tends to lie beneath L1 - L3 where as the left tends to lie under L2-L4. The reason the right kidney is less mobile than the left is that it tends to be almost entirely enclosed within the renal fossa of the caudate lobe of the liver. The kidneys are enclosed within a layer of fat and this increases with the obesity of the animal.

Medially to the right kidney you will find the caudal vena cava and the right adrenal gland can be found dorsolateral to this structure but still medially to the kidney. Ventrally can be found the Descending duodenum with the right pancreatic limb more towards the ventromedial aspect. In females the right ovary can be found caudoventrally.

The Cranial pole of the left kidney contacts the greater curvature of stomach it also contacts the spleen on its dorsomedial aspect as well as potentially contacting the left limb of the pancreas. The left adrenal gland can be found at the medial aspect of the cranial pole. The Caudal pole of the left kidney contacts the Small intestine and the Descending colon. At its caudoventral aspect in females is found the left Ovary.

Ruminants

Due to the rumen taking up most of the left side of the abdomen it is normal in the bovine to find both of the kidneys on the right side. In the ovine the kidneys are surrounded by very thick masses of fat which reduce the impact of the rumen on their location. The kidneys in the living animal vary their position substantially with respiration and with the pressure of the other organs.

The right kidney has a retroperitoneal attachment to the "sublumbar" musculature. Cranially it touches the liver. In the dead specimen the right kidney occupies the region between the last rib and somewhere between the 2nd and 3rd lumbar vertebrae’s transverse process. The right kidney usually contacts pancreas, duodenum, adrenal glands and colon as well as the afore mentioned liver.

The left kidney in the bovine is to be found caudoventrally to the right one usually in the region between the 2nd and 4th lumbar vertebrae

Porcine

The left and right kidneys are more or less aligned in the pig unlike other species. The kidneys of the pig are embedded in lots of fat and lie against the psoas muscle. They span the distance between the last rib cranially and the 4th lumber vertebrae caudally. The right kidney does not touch the liver unlike other species and is related ventrally to the descending duodenum and jejunum. The left kidney is ventrally related to the ascending colon, the base of the caecum and the pancreas.

Equine

The kidneys of the horse are both enclosed in a fat capsule. Dorsally they rest against the psoas muscle and against the diaphragm.

The right kidney is to be found ventrally to and between the last 2 ribs and first lumbar transverse process. Cranially it touches the liver and caudally it is attached to the pancreas and the base of caecum. The duodenum winds around its lateral and then ventral surfaces. Medially is the caudal vena cava and adrenal gland.

The left kidney is between the last rib and 3rd transverse process. Its ventral surface is almost completely covered by the peritoneum and contacts the small intestine and and small colon. The spleen contacts it cranioventrally. Medially is the left adrenal gland and aorta.

Renal Blood Supply

  • Supplied by renal arteries
  • Arise from aorta
  • 3-4mm diameter - dog
  • Often divide into dorsal and ventral branches before entering kidney
  • Common to find double the normal number - dog

Left Renal Vessels

  • Left renal artery
    • Originates 2cm caudal to the right renal artery
    • ~3-4cm long - dog
  • Left renal vein
    • Immediately ventral to artery
    • ~3-4cm long - dog

Right Renal Vessels

  • Right Renal Artery
    • 2cm cranial to left renal artery
    • 4 cm caudal to cranial mesenteric artery
    • Passes dorsal over the caudal vena cava
    • ~4-5cm long - dog
  • Right Renal Vein
    • Ventral to artery
    • ~4-5cm long - dog

Internal Vascularisation

Once the renal artery enters the kidney is divides into the interlobar arteries. These pass through the gaps between the renal pyramids as the reach the junctions between the cortex and medullar they branch into the arcuate arteries which move over the base of the pyramids. From these come the interlobular arteries which supply the individual lobules of the cortex. These arteries then branch many times to supply individual glomeruli. The capillaries of the glomerulus then rejoin to form one vessel which then forms the peritubular capillaries of that nephron. The interlobular arteries are examples of end arterioles and there are few anastomoses. Obstruction of one of these arterioles causes ischaemic damage in the kidneys. This is also potentially the case with the interlobar arteries.