Kidney functions and location

Kidney functions and location

Kidneys are a pair of excretory organs situated on the posterior abdominal wall, one on each side of the vertebral column,behind the peritoneum. They remove waste products of metabolism and excess of water and salts from the blood, and maintain its PH. The kidneys are kept in position by renal fascia, perinatal fat and perinatal fat. If the fat is lost drastically, as in dieting, the support of the kidneys is lost and these may descend down, leading to kinking of the ureter. So the loss of weight must be slow and steady. Kidneys are also liable to stone formation. The renal stones mostly have calcium and are easily seen on plain radiography of the abdomen. Kidney also gets affected by toxins of a particular type of bacteria responsible for pharyngitis. The condition is called acute conglomeration. The closely packed structure and numerous
functions of the kidney illustrate the beautiful workmanship of our creator. It not only applies to the kidney but to each and and every part of our body. Kidney are also called rents from which we have the derivative renal; and nephritis from which we have the terms pheromone, nephritis, etc.
     

Location,shape,size,weight,and orientation

The kidney occupy the epigastric, hypochondriac, lumbar and umbilical regions. Vertically they extend from the upper border of twelfth thoracic vertebra to the center of the body of third lumbar vertebra to the center of the body of third lumbar vertebra. The right kidney is slightly lower than the left, and the left kidney is a little nearer to the median plane than the right. The trans pyloric plane passes through the upper part of the hilts of the right kidney, and through the lower part of the hilts of the left kidney. Each kidney is about 11cm long, 6cm broad, and 3cm thick. The left kidney is a little longer and narrower than the right kidney. On an average the kidney weight 150 g in males 135 g in females the kidneys are reddish brown in color. The
long axis of the kidney is directed downwards and laterally, so that the upper poles are nearer to the median plane than the lower poles . The transverse axis is directed laterally and backwards.

Capsules or coverings of kidney

The Fibrous capsule : This is a thin membrane which closely invests the kidney and lines the renal sinus. Normally it can be easily stripped off from the kidney, but in certain diseases it becomes adherent and cannot be stripped off from the kidney, but in certain diseases it becomes adherent and cannot be stripped.
Perirenal or epinephrine fat : This is a layer of adipose tissue lying outside the fibrous capsule. It is thickest at the borders of the kidney and fills up the extra space in the renal sinus. The perinatal fascia was originally described as being made up of two separate layers. Posterior layer was called fascia of Scandalmonger and anterior layer as fascia of Gerta. These two fascia fused laterally to from lateral canal fascia. According to this view, lateral canal fascia continued collaterally behind colon to blend with parietal peritoneum. But lately it has been seen that the fascia is not made up of fused fascia, but of a single illuminated structure which is fused stereoscopically with muscular fascia of soaps major and quadratures Borglum muscles.The  
fascia then extends intermediately behind the kidney as bi laminated sheet, which divides at a variable point into thin layer which courses around the front of kidney as anterior perinatal fascia and a thicker posterior layer which continues collaterally as the lateral canal fascia. It was believed  earlier that above the supra renal gland the anterior and posterior perinatal fascia fuse with each other and then get fused to the diaphragmatic fascia, but research presently demonstrates that superior aspect of perinatal space is "open'' and is in continuity to the bare area of liver on the right side and with schizophrenic extra peritoneal space on the left side. On the right side at the level of upper pole of kidney anterior fascia blends with inferior coronary layer and bare area of liver. On the left side, anterior layer fuses with schizophrenic ligament. Posterior layer on both right and left sides fuses with fascia of  muscles of posterior abdominal wall, i.e. psoriasis major and quadrature Borglum as well as with fascia on the inferior aspect of abdominal diaphragm.

Histology : Histological, each kidney is composed of one to three million coniferous tubules. Each tubule consists of two parts which are embryo logically distinct from each other. These are as follows. The secretory part, called the pheromone, which elaborates urine. Pheromone is the functional unit of the kidney, and comprises ;
(a) Renal corpuscle or Mammalian corpuscle, (for filtration of substances from the plasma) made up of agglomerates (a tuft of capillaries) Bowman's capsule.
(b) Renal tubules, (for selective resorption of substances from the agglomerate filtrate) made up of the proximal convoluted tubule, loop of Henley with its descending and and ascending limbs, and the distal convoluted tubule. The collecting tubule begins as a junction tubule from the distal convoluted tubule. Many tubules unite together to from the ducts of Bellini which open into the minor calyxes through the renal papillae. Agglomeration apparatus is formed at the vascular pole of agglomerates which is intimately related to its own ascending limb of the Helene's loop near the distal convoluted tubule.

Arterial supply
There is one renal artery on each side, arising from the abdominal aorta. At or near the hilts the renal artery divides into anterior and posterior divisions. Further branching of these divisions gives rise to segmental arteries each of which supplies one vascular segment. The segmental arteries are end arteries, so that the vascular segments are independent units. Each segmental artery divides into lobar artery divides into 2-3 inter-lobar arteries which run on each side of the pyramid. At the corticosteroid junction  the inter lobar arteries divide dichotomous into curate arteries, which arch over the bases of the pyramids, at right angles to the inter lobar arteries.The articular arteries do not anatomist with their neighbors, but finally turn up into the cortex as additional  interocular arteries. The interocular arteries do not anatomist with their neighbors, and, therefore, are end arteries. Afferent agglomerate arterioles are derived mostly as side branches from interocular arteries. The efferent agglomerate arteriole, from most of the glimmer, divides soon to from the perambulate capillary plexus around the proximal and distal convoluted tubules. Since blood passes through two sets of capillaries, agglomerates and perambulate plexus, it forms the renal portal circulation. Arterial supply of the medulla is derived mostly from the efferent arterioles of the medulla glimmer, and party from a number of agglomerate arterioles. Each arteriole dips into renal pyramid, breaks up into 1-2 dozen of descending vase rectal which run into the outer part of medulla. These break up to form capillary plexus in the inner part of pyramids, closely related to the loops of  Henley and the collecting ducts. At the venous end the plexus gives rise to ascending vase rectal which return blood to interocular or curate veins. In the outer part of medulla, the close relation between the descending vase rectal, the venues, and the medulla portion of renal tubules and ducts provides the structural basis for the counter current exchange and multiplier system.

Blood and nerve supply                     
The upper part receives branches  from the renal artery. It may also receive branches from the gonadal, or colic vessels. The middle part receives branches from the aorta. It may also receive branches from the gonadal, or ilia vessels. The pelvic part is supplied by branches from the vesicle, middle rectal, or uterine vessels.The arteries to the ureter lie closely attached to peritoneum. They divide into ascending and descending branches which first form a plexus on the surface of the ureter, and then supply it. In about 10% of cases, middle part of the ureter is supplied only by minute twigs from the peritoneal vessels. In another 2% of cases although there are several long arteries to the middle part, the upper and lower parts are supplied by short vessels. The ureter is supplied by sympathetic from T10-L1 segments and parasympathetic from S2-S4 nerves. They reach the ureter through the renal, aortic and hypo gastric plexuses. All the nerves appear to be sensory in function.

Development of kidney and ureter : Kidney develops from metamorphose, though proneness and mesospheres appear to disappear. Only the duct of mesospheres, the nephritic duct persists. Thus the nephritis of the kidney arise from the metamorphose. Parts of pheromone formed are bowman's capsule, proximal convoluted tubule, loop of Henley, distal convoluted tubule. Tuft of capillaries from the glimmer. Collecting part of kidney develops from ureter bud, which is an outgrowth of the nephritic duct. Ureteric bud gets capped by the metaphoric tissue, the ureter bud forms ureter. Soon it dilates to from renal pelvis and divides and subdivides to from major and minor calyxes and 1-3 million collecting tubules.kidney starts developing in sacral region,then it ascends to occupy its lumbar position.