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The Kidneys

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The Kidneys





The kidneys are an important part of the endocrine system. The main function of the two kindeys is to filter blood, produce waste products called urine and maintain the body's fluid composition (Daniels, 2007). The kidneys are also responsible for converting vitamin D into an enzyme called renin which helps maintain blood pressure. The kidneys are bean shaped organs that are situated behind the abdominal cavity and are protected by the lower part of the ribcage (Roberts, 2010).


A link below has been provided on the kidneys function -




Kidney Facts



  • An adult kidney weighs approx 4-5 ounces
  • The standard size kidney is 4-5 inches long and approximately 1 inch thick
  • The kidneys make up less than 0.5 percent of the body's weight.
  • 3600 pints of blood is received by the kidneys every 24 hours.


Inside the Kidneys


The outside part of the kidneys contains approximately a million nephrons that are responsible for filtration. The nephrons are responsible for filtering approximately 180 litres of blood plasma per day and expelling 1-2 litres of urine as an excretory product (Roberts, 2010). Roberts (2010) notes the 85 percent of nephrons are short-looped whilst the other 15 percent is long-looped. The excretory products from the nephrons is carries by collecting ducts to renal pelvis where urine flows into the ureter and the bladder for excretion.



Kidney Anatomy


The kidney is surrounded by three layers of tissue. The innermost layer of the kidney is the renal capsule which covers the kidneys. The next layer is a fatty layer called adipose which supports and protects the kidneys. The third and outer layer is called the connective tissue which anchors the kidneys to the surrounding structures (Daniels, 2007). 


The internal structure of the kidneys consist of two regions. The first region known as the renal cortex is reddish and smooth where as the second region is the renal medulla which a dark red in colour. The renal medulla contain renal pyramids which comprise of tiny urine gathering sacs. Within the renal cortex, are glomerulas which are the key filtering networks.


 Kidney Failure


When kidneys fail they can no longer effectively filter the waste products from the blood. Nitrogenous wastes build in the blood increasing the PH acidic rates to a dangerous level. Symptoms of kidney failure include nausea, vomiting, edema and fatigue (Daniels, 2007). A regular blood test shows high levels of urea (protein) and creatine (muscle metabolism). Kidney failure occurs when 85-90% of the kidney's nephrons are destroyed. Nephrons may deteriorate for a number of reasons which include:









Daniels, P et al. (2007) Body: The Complete Human - How it grows, How it works and how to keep it healthy and strong. National Geographic Society USA.




Roberts, DR A. (2010) The Complete Human Body: The definitive visual guide: DK Publishing - New York.




Read 2659 times Last modified on Thursday, 17 September 2015 09:35

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