What are kidneys? functions and embryonic development of kidney along disorders related to kidneys


The bodies of living organism are very complex. In the bodies of living organism there are many organs and systems working simultaneously to sustain life and those various organs that are working in the body and as a result of their actions body can work these organs and various systems in the body carry out various process along the same time there are countless metabolic activities occurring in the body and as result of all these activities and cycles of the body various types of waste are produced that may be nitrogenous wastes metabolites urea ammonia or any other type of such waste and if they get accumulated in the body for some time they can be harmful for the body in many ways so they should be continuously removed from the body and for this purpose there is structure present in the body that goes by the name of kidney. These kidneys are responsible for the filtration of blood and removing these harmful waste from the blood and hence removing them from the body in the form of urine. If we talk about the composition of the body than the component that makes about 70 % of the body is water and there should be system or organ that should be responsible for the regulation of water in the body along with water there are also many electrolytes salts in the bodies of living organisms that very crucial for the life and perform a lot of functions in the body. Kidney is also responsible for the regulation of these salts electrolytes and water in the body by removing extra in the form of urine so that a balance can be maintained in the body. In normal humans there is a pair of pair located highly in the posterior side of the abdomen cavity one on each side of the spine or we can also say that they are present left and right in the retro-peritoneal space or we can also describe the position of the kidneys in the body than we can also say that humans have two kidneys placed in the abdominal cavity on both sides of the vertebral column attached to the dorsal abdominal wall. There also have a shape similarity with beans that why they are also known as the bean shape organs kidneys are about 4-5 inches long. There is a minor difference in the position of both of the kidneys and it is that the right kidney is slightly lower than the left kidney and the reason for this unequal position is that as the right lobe of the liver is above the right kidney and this right lobe of the liver puts a slight pressure on the right kidneys if we talk more about the position of kidney than we can say that the left kidney is about the level of some of the vertebrates and they are between the T-12 and L-3. The right kidney is below the diagram and posterior to the spleen. The upper parts of the kidneys are partially protected of two of the ribs and they are also known as the floating ribs and these are the 11th and the 12th rib. The superior pole of the right kidney is adjacent to the liver as for the case of left kidney it is next to the spleen. Kidneys are not only the major excretory organs of humans but also act as an osmo-regulatory. The bean shape structures of the body that are the kidneys have two boarders one is the concave border and the other is the convex boarder. On the concave boarder or side of the kidney there is a depression that is known by the name of the renal hilum and this is the point of the kidneys from where everything enters and exit such as from the point the renal artery rein ureters enter as well as the exit also the blood supply given to the kidney from the filtration enters from here and after filtration goes out from here. On a cross two regions of kidney or layers of the kidney are prominent are they as following

  • renal cortex
  • renal medulla
renal cortex is the outside or the outskirt of the kidney whereas inner to this cortex is the medulla cortex is pale in color as compared to the medulla and the reason for this is that there is a more blood vessel concentration in the medulla also there is a greater interstitium in the medulla region of the kidney as compared to the cortex. On the supra position of the kidney or on the top of the kidneys there is a very important gland present that is known as the adrenal gland. If we talk about the main structures present in the kidneys then they are as following

  • renal cortex
  • renal medulla
  • renal pelvis
  • minor calyx 
  • major calyx 
  • papilla 
  • renal sinus
  • renal column
  • renal pyramids
  • capsule of the kidney 
  • ureter that carries the urine out of the kidneys and into the bladder
 both of the kidneys and the adrenal glands present on the is covered by two layer of fats and the name of these fat layers  are as following

  • perirenal fat
  • pararenal fat
if we talk about the weight of the kidneys as compared to the rest of the body than they are just 1%  of the total body weight. Like the neurons that are the structural and the functional unit of the nervous system similarly nephrons are the structural and the functional unit of the renal system or the kidneys and these are these structures in the kidney where the filtration of blood and production of urine takes places there are about million of these nephrons in each kidney. There are two different types nephrons in the kidneys and they are as following

  • cortical nephrons 
  • juxtramedullary nephrons 
other than filtration of the blood kidney perform various other functions and if we talk to conclude these all functions of the in points than we can describe them as

  • urine formation 
  • osmoregulation in the body 
  • regulation of arterial pressure 
  • regulation of erythrocyte production 
  • regulation of acid base balance
  • regulation and production of 1,25 dihydroxyvitamin D-3 
  • glucose synthesis
every organ of the body for its proper functions needs bloods supply as well as the nervous supply. If we talk about the blood supply of the kidney than we say that kidneys on each heart beat receives 20% of the blood if we consider the oxygenated blood supply of the kidneys than we can say kidneys gets there oxygenated blood from the

  • renal artery
which further divides into

  • interlobar arteries 
  • arcuate arteries 
  • interlobular arteries 
and hence ultimately into the supply of the glomerular

  • afferent arterioles 
and if we talk about the removal of the deoxygentaed blood from the kidney than it is removed from the kidney through the

  • renal vein 
and it form in such a way that the glomerular capillaries form the

  • efferent arterioles 
than after this there is formation of the

  • interlobular arteries 
  • arcuate vein 
  • interlobar vein 
  • and hence ultimately renal vein 
  • which than goes into the inferior vena cava 
if we talk about the nervous supply of the kidneys than we can say that kidney and the nervous communicates through the renal plexus such that the sympathetic nervous supply cause vasoconstriction in the kidneys where as the kidneys gets parasympathetic nervous supply from the vague nerve there is also sensor input of the kidney that comes from the spinal cord and specially from the levels of the spinal cord that is near the vertebrates T-10 an T-11.

embryonic development of kidneys
Development of kidneys during the embryo development is known by a specific term and that is nephrogenesis and the development of kidneys in an embryo is from the mesoderm during the development of the kidneys there are three main structures initially which derive from intermediate mesoderm and these structures are as following 
  • pronephros
  • mesonephros
  • metanephros
human kidney development begins as early as the third week of the embryonic development followed by the formation of the pronrphrons than is than followed by the formation of mesonephrons at 4 week and the metanephrons at the 5th week of the gestation. The first glomeruli appears at 9th week of gestation in humans and the development of kidney or nephrogenesis is completed by the 36th week of the gestation. Fetal kidneys does not produces urine not until the birth. The mesonephrons begins to develop as the pronephros is regressing during the 4th week of the gestation it starts as a series of S shaped tubules which acquire capillaries to become a glomerulus and the tubules around the glomerulus will form a bowmann's capsule this final urinary organ appears during the fifth week the collecting system of ducts from the ureteric bud which in turn is an outgrowth of the mesonephric duct this bud than dilates forming the renal pelvis than the renal pelvis will differentiate into the major calyx which will do the same for 12 or more generations to form the minor calyx by the fifth generation renal pyramids are formed. Than these tubules and the glomeruli will form the or give rise to the nephron which is the structural and the functional unit of the renal system continuous expansion of these tubules will from the convulated tubules of the kidney and the loop of henle.

functions of the kidney
In living organisms also such as in humans kidney or renal system perform a lot of important functions and some of the important functions that kidneys perform in the bodies of living organisms are ass following 
  • urine formation 
  • osmoregulation in the body 
  • regulation of arterial pressure 
  • regulation of erythrocyte production 
  • regulation of acid base balance
  • regulation and production of 1,25 dihydroxyvitamin D-3 
  • glucose synthesis
formation of urine 
One of the main and the most important functions of the kidney is the urine formation by which kidney excretes a variety of waste products that are mainly produced from the metabolism such all of the urine formation in the kidney takes places through the structural and the functional unit of the kidney that are the nephrons in which there is first filtration than re-absorption than is than followed by the secretion and by this there is urine formation and the urine that is formed leaves the kidneys and goes to the urinary bladder through ureters. One of the main and crucial function of kidney is maintain proper level of waste salts and electrolyte in the body and for this purpose to ensure that there is proper amount of water in the body kidneys adopts some mechanisms one of which is 
  • counter current multiplier 
along with this mechanism to ensure proper levels of water and salts in body kidneys uses many hormonal mechanism and some of the hormones used for this purpose are as following 
problems related to kidney
like any other organ of the body problems can also arise in the kidneys and it can be due to various reasons such as it may be associated with the life style it may be some kind of infection some kind of stone formation destruction of some of the levels of the kidney genetic disorders or there can be various other factors that can can lead to kidney disorders. In all of the kidney disorders there are some symptoms that are common or there are symptoms that can appear as a result of any sort of problem in the kidney and some of these symptoms are as following 

  • reduced amount of urine 
  • pain or pressure in your chest
  • confusion
  • seizures 
  • persistent nausea
  • swelling of legs ankles and feet
  • dry and itchy skin
  • less energetic than normal 
  • having trouble sleeping 
  • urine is foamy 
  • experience persistent puffiness around eyes
these were some of the common symptoms that may appear as as a result of any sort of renal disorders but there are some specific test to detect any type of renal abnormality in the body and these test are as following

  • kidney ultrasound
  • urinalysis
  • computed tomography
  • ureteroscopy
  • magnetic resonance imaging 
  • urine and blood cultures
  • kidney biopsy
where if we talk about some common methods of medications given to patients with renal disorders than that are as following

  • antibiotics
  • lithotripsy 
  • nephrostomy 
  • dialysis
  • peritoneal dialysis
  • hemodialysis
  • kidney transplant 
there were the common symptoms associated with kidney disorders or general treatment methods or the test by which we can detect any type of kidney disorders or kidney abnormalities in the body but there are some specific disorders of the kidneys that are as following

  • renal cyst
  • nephrogenic diabetes insipidus 
  • minimal change disease
  • interstitial nephritis 
  • kidney cancer
  • hypertensive nephropathy
  • papillary necrosis
  • end stage renal disease
  • chronic renal failure
  • acute renal failure
  • polycystic kidney disease
  • nephrotic syndrome 
  • kidney stones
  • glomerulonephritis
  • pyelonephritis  

renal cyst
Renal cyst are sacs of fluid that forms in the kidneys they are called as cyst as they have a thin wall that contains a water like fluid in it. Some of the renal cysts may appear more complex and have a thicker wall or contain a solid material instead of fluid some of the symptoms that are shown in the renal cyst are as following 
  • fever
  • pain between ribs and pelvis 
  • upper abdominal pain
  • blood in urine 
  • dark urine 
  • swelling of abdomen 
the methods that are adopted for the treatment of renal cyst are as following 
  • surgery 
  • sclerotherapy  
exact reason for the formation of renal cyst is not clear but it is believed they are caused as the surface layer of the kidney weakens and forms a pouch that is than filled with filled which than develops into a cyst 

nephrogenic diabetes insipidus
Nephrogenic diabetes insipidus is a rare kidney disorder that may be inherited or acquired it is caused by complete or partial resistance of kidneys to vasporesin or ADH most cases of nephrogenic diabetes insipidus are inherited as X- linked recessive disorder it is not that in this disease ADH is not produced ADH is produced by kidneys become partially or complete;y resistant to this hormone. Some of the symptoms that is generally related to this disorder are as following 
  • excessive thirst 
  • polyuria
  • muscle pain
  • irritability
  • lethargy
this disorder is generally treated by the following 
  • changing lifestyle by taking a salt a low protein dirt that reduces urine output 
  • diuretics
  • non-steroidal anti inflammatory drugs 
minimal change disease

Minimal change disease is a kidney disease is a kidney disease in which large amounts of protein is lost in the urine such that large amount of protein is found in the urine that is not normal. Normally kidneys can filter blood without losing any of the proteins that is supposed to remain in the circulatory system but in such cases when the kidney filters are damaged than protein slips through them and gets into thee urine which and this is known as the proteiuria

interstitial nephritis
Interstitial nephritis is a kidney disorder in which the spaces between the kidney tubules becomes swollen this can interfere with the normal functioning of the kidneys some of the symptoms that are associated with this disorder are as following 
  • increased urine output 
  • blood in urine 
  • dark urine
  • nausea
  • vomiting
  • fever 
  • rashes
  • elevated blood pressure
  • confusion 
  • drowsiness
  • sudden weight gain
some of the test are used for the detection of this disorder are as following
  • kidney biopsy 
  • urinalysis
  • complete blood count 

renal papillary necrosis 
Renal papillary necrosis is a form of nephropathy involving the necrosis of the renal papilla lesions that characterizes the renal papillary necrosis come from an impairment of the blood supply some of the common symptoms of this disorder are as following 
  • painful urination 
  • frequent urination
  • fever
  • tissue pieces in the urine 
  • cloudy urine 
  • back pain 


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