Basic of Kidney

Kidneys are a pair of solid organ situated on either side of the spine across T 11 to L 3 vertebra. The functioning unit of kidney is called a “nephron” . Each kidney contains about 1 million nephrons. Each nephron has a network of capillaries called ‘glomeruli’ where blood filters out the wastes. This filtrate is collected in the ‘Bowman’s space’ from where it travels through the ‘tubules’, where the filtrate is reprocessed to finally make the urine which is discarded

Renal failure is loss of excretory function of the kidneys, leading to solute accumulation in the blood. However, there are several other kidney diseases, where excretory function is intact but other kidney functions may be abnormal for e.g. nephrotic syndrome, renal tubular acidosis, renal rickets, salt losing nephropathy, etc. Hence, kidneys are not only an organ of excretion but have many other important functions which may be impaired without affecting the excretory function. It is important to know the different functions of kidneys which can be enlisted as follows:

1. Solute or waste removal, which also includes removal of drugs, metabolites, toxins, and certain poisons. Hence, we need to modify the dose of certain drugs in presence of kidney failure.

2. Fluid balance.

3. Acid Base balance. is one of the most important organs for acid-base regulation. In certain diseases, patients may have renal tubular acidosis with no abnormality in excretory function.

4. Electrolyte (Na, K) regulation. This is a very important function of the kidneys and when impaired can give rise of different electrolyte disturbances like hyponatremia or hypernatremia, and hypokalemia or hyperkalemia.

5. Secretory function – Kidneys secrete various enzyme and hormones which has important role in human physiology.

    a. Renin – This regulates blood pressure in an individual.

    b. Erythropoeitin – This regulates hemoglobin levels.

    c. Active vitamin D – by virtue of 1-α hydroxylation of 25 (OH) vitamin D, it forms active form of vitamin D.