Renal Anatomy

What are kidneys? 


Kidney is particularly a wrist size organ present in our renal system. It works as a natural filter in our body and removes excess toxins and waste fluids from our body in the form of urine. It also filters the deoxygenated blood before sending it back to heart. 


Some critical roles which are performed by our kidneys in our body, includes: 

  • Producing hormones which are responsible for production of red blood cells, maintaining bone health and regulating blood pressure. 
  • Filtration of waste products from our body. 
  • Balancing fluids in our body.
  • Filtration of excess minerals from our blood. 




Nephrons are the one of the most necessary parts of our both kidneys. Around 1 million of nephrons are present in each kidney and each of it has its own internal set of structures. Nephrons specifically perform the function of taking in blood and metabolizing nutrients and helping the waste products and toxins to pass out from the filtered blood. 


Renal corpuscle 


The renal corpuscles are also known as malpighian bodies. After getting passed from nephrons the blood enters the renal corpuscle.  Renal corpuscle comprises two structures additionally: 

  • The glomerulus: Glomerulus are nothing else than the bunch of capillaries which helps in the absorption of protein from the blood passing through the renal corpuscle. 
  • The bowman capsule: The fluids which remained left after the absorption of the protein is called capsules urine which pater passes from the Bowman capsule to the renal tubules. 


Renal tubules 


The renal tubules are the group of tubules which starts just after the Bowman capsule and ends at the collecting duct. 


Renal tubules consists many parts which mentioned below: 


  • Proximal convoluted tubules: This is the part of renal tubules which is responsible for the absorption of the sodium, water and glucose from the blood. 
  • Loop of Henle: This is the part of renal tubules which is responsible for the absorption of the chloride, potassium and sodium from the blood. 
  • Distal convoluted tubules: Lastly these tubules absorb more sodium from the blood and assimilate urine and potassium. 


After getting to the last tubule the leftover fluid gets diluted and filled with urea which is a byproduct of protein metabolism that later gets released in the form of urine. 


Renal cortex 


Renal cortex is the most outer part of the kidney in which glomerulus and convoluted tubules are present. 


The renal capsules which is a layer of fatty tissue surrounds the renal cortex from its outer edges. Inner structures of the kidney are protected by the renal capsule and the cortex. 


Renal medulla


Renal medulla is a smooth tissue which is present in kidneys. Loop Henle and renal pyramids are present in them. 


Renal pyramids


Renal pyramids are the small structures present in kidneys which contain the strings of nephrons and tubules, these tubules help in transportation of fluids into the kidney.  Afterwards the fluid moves from the nephrons to the inner structure which transports and collects urine out of the kidney. 


Collecting ducts


At the end where filtered fluids exit nephrons a part of the renal system known as collecting duct is present. 


Once the fluid reaches the collecting duct it moves to its final stop in the renal pelvis. 


Renal pelvis 


Renal pelvis is an organ which appears like a funnel in shape present in the innermost part of the kidney. It performs the role of pathway for the fluid to reach the bladder. 



Calyces is present in the first part of the renal pelvis. Calyces are the cup shaped spaces which perform the role of collecting the fluid before it moves to the bladder. It is also the place where extra fluids and urine are converted into urine. 




It is a small opening which is present at kidney’s inner edge, the renal pelvis gets pass through it with: 

  • Renal arteries: It performs the role of bringing the oxygenated blood from the heart to the kidney for the process of filtration. 
  • Renal vein: It performs the role of carrying filtered blood back from the kidney to the heart. 




Ureter is the tube made up of muscle which sends urine to the bladder where it is collected and later exits the body. 


Renal conditions 


As many of us know that the kidney performs the critical functions and confronts many toxins because of which they can be prone to assorted problems. 


Various renal conditions includes: 

  • Renal failure
  • Kidney stones 
  • Nephrotic syndrome 
  • Uremia 
  • Hydronephrosis 
  • Kidney cysts 
  • Pyelonephritis 
  • Acidosis 
  • Azotemia 
  • Polycystic kidney disease 
  • Urinary tract infections 
  • Acute nephritis 
  • Chronic kidney disease 
  • Caliectasis 


Symptoms of kidney problems 


A variety of problems can be caused by kidney conditions. Some common symptoms of kidney problems includes: 

  • Trouble in sleeping 
  • Skin problems 
  • Swelling in foot or ankles 
  • Appetite loss
  • Muscle cramps 
  • Blood in urine 
  • Foamy urine 
  • Unable to concentrate
  • Tiredness 
  • Sudden increased or decrease in urination 


If you have any of these symptoms 

visible  in you then you should contact a doctor as soon as possible. Your doctor will suggest you some kidney function tests to make a diagnosis depending upon your symptoms. 


Know the risk factors 


A variety of things can be responsible for the development of kidney conditions in you. You should always have a routine kidney function test if you are suffering from any of these diseases: 

  • Excess weight 
  • Diabetes 
  • Genetic history of kidney disease 
  • High blood pressure 


Renal pyramids


Renal pyramids also known as malpighian pyramids are particularly the funnel shaped kidney tissue. Around 8 to 17 renal pyramids are present in the innermost part of the kidney, which is known as renal medulla. Only 7 renal pyramids are present generally in humans. The outer portion of the kidney which is faced by the base of each pyramid is known as the renal cortex. In between renal medulla and renal capsule the renal cortex is located. Renal cortex is a hard layer of tissue which surrounds the kidney. A thick layer of connective  fatty tissue is present in the renal capsule.  Renal pyramids have strip-like appearance because they are present in the parts of parallel nephrons. Nephrons are the most elemental operational unit of kidney which performs the process of filtration of blood and it also helps in maintaining the water density and soluble substance such as sodium salt in the body. After the completion of the filtration process the required substances are reabsorbed and others are removed from the body in the form of urine. The waste elimination helps the body for regulating blood pressure and volume. 


Renal veins 


Two distinct renal veins is present in body, which are left and right. These two renal veins are part of inferior vena cava. These renal veins particularly perform the sending of deoxygenated blood back from the kidney to the heart. Each renal vein gets separated into two parts when it enters the kidney, while the front part is assisted by the anterior veins. These are the veins which are responsible for draining blood from the ureter, which works for the transportation of urine from the kidney to Urinary bladder. This veins differ from the renal aorta. The renal aorta works for delivering the oxygenated blood to the kidney unlike other veins. Renal aorta carries blood to the kidney while other veins send the blood away. 


Two common diseases which are notably involved with renal veins are, in the case of blood clot renal vein thrombosis can be caused. Symptoms of renal vein thrombosis include blood in urine and diminished flow of urine. This disease can be treated by the clot removal surgery or anticoagulants. Another disease which is related with the renal veins is nutcracker syndrome (NCS), this disease occurs when the renal veins get suppressed by the abdominal aorta and the superior mesenteric artery. 


Renal artery


Renal artery is one of the vessels which lead off from the abdominal aorta that go to the kidneys. 


Hilum is  the entrance point for the renal artery. Normally after entering through the hilum the renal artery gets divided into two different branches, which later gets split into the number of small arteries, which are known as nephrons and work for sending blood to different parts of the kidneys. 


After the completion of this process then the blood gets again sent to the inferior vena cava and right side of the heart with the help of renal vein. 


Usually it is noticed that the average person’s kidney gets around one fourth blood of the heart’s output which is appropriately 1.2 liters every minute. Self regulating system is present in the body, which helps the body by increasing or decreasing the blood flow for adapting to stress. To compensate low or high blood pressure receptors are present in the smooth muscular layer of the renal arteries which allows the arteries to expand or contract. 


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