Sangeetha Pulapaka

It is easy to think of the kidneys as simply excretory organs that produce urine to remove waste products from the body. In fact, they are much more complex, performing many functions which have wide ranging physiological effects. The main functions of the kidney are: To regulate:

  1. Extracellular fluid volume
  2. Extracellular fluid electrolyte composition
  3. Total body water volume
  4. The body’s acid-base balance
  5. Arterial blood pressure

The above figure is a  concentration of a typical nephron with each distinct region labelled.

The basic functional unit of the kidney is the nephron. Each kidney contains approximately 1 – 1.5 million nephrons. Each nephron is basically a folded up tube; situated proximally is a complex capillary network and capsule where plasma is filtered (the glomerulus and Bowman’s capsule), which produces the glomerular filtrate, and situated distally are the collecting ducts from which urine drains. Between Bowman’s capsule and the collecting duct is the proximal convoluted tubule (PCT), the loop of Henle and the distal tubule, each of which serve specific functions. The nephrons are all orientated such that the glomerulus and Bowman’s capsule lie in the cortex with their loop of Henle and collecting duct pointing towards and entering the medulla.

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