Kidney ( Part -1 )

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Synonyms

The kidneys are also called renes from which we have the derivative renal; and nephros from which we have the terms nephron, nephritis, etc.


Definition

Kidneys are a pair of excretory organs situated on the  posterior abdominal wall, one on each side of the vertebral column, behind the peritoneum. They remove
waste products of metabolism and excess of water and salts from the blood, and maintain its pH.


Location

The kidneys occupy the epigastric, hypochondriac, lumbar and umbilical regions. Vertically they extend from the upper border of twelfth thoracic vertebra to the centre of the body of third lumbar
vertebra. The right kidney is slightly lower than the left, and the left kidney is a little nearer to the median  plane than the right.
The transpyloric plane passes through the upper part of the hilus of the right kidney, and through the lower part of the hilus of the left kidney.


Shape , size , weight and orientation

Each kidney is about L1 cm long, 6 cm broad, and 3 cm thick. The left kidney is a little longer and narrower than the right kidney. On an average the kidney weighs
150 g in males and 135 g in females. The kidneys are reddish brown in colour.
The long axis of the kidney is directed downwards and laterally, so that the upper poles are nearer to the  medianplane than the lower poles. The transverse axis is directed laterally and backwards.
In the foetus the kidney is lobulated and is made up  of about 12 lobules. After birth the lobules gradually fuse, so that in adults the kidney is uniformly smooth.
However, the evidence of foetal lobulation may persist.

External features

Each kidney is bean-shaped. It has upper and lower poles, medial and lateral borders, and anterior and posterior surface.


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