Question

What do you meant by Kidney??​

Answer 1

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There is a pair of kidneys in the human body.Each kidney is brick red in colour and is bean shaped.They filter out waste products from the blood.These wastes form a light yellow coloured liquid called the urine. In this way,the blood gets purified by the kidneys.Kidneys help in removing not only harmful substances, such as urea, but also excess water, from the blood.

Answer 2

Answer:

Kidneys :

• Shape and Size: Kidneys are reddish brown, bean-shaped structures situated between the level of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity. Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120-170 g. Left kidney is little higher than the right one because of more space being occupied by the liver on right side. So, only in human beings is the right kidney placed slightly below the left one but in other mammals, e. g., rabbit, the left kidney is lower than the right kidney.
• Towards the centre of the inner concave surface of the kidney is a notch called hilum through which the ureter, blood vessels and nerve pass.
• Kidney is covered by 3 protective layers which are as follows :

1. Renal Capsule : It is the innermost, tough protective cover made up of white fibrous connective tissue, with few elastic fibres and few muscles.
2. Adipose Capsule : It is the middle cover involving adipose tissue and acts as shock absorber.
3. Renal Fascia : It is the outermost fibrous cover linking it with the abdominal wall.

• As the kidneys are fused with the body wall on the dorsal side, peritoneal cover is present only on the ventral side. This arrangement is called retroperitoneal arrangement.
• Internal structure : Inner to the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces. The outer layer of kidney is a tough capsule. Inside the kidney, there are two zones, an outer cortex and an inner medulla. The medulla is divided into a few conical masses projecting into the calyces. The cortex extends in the between the medullary pyramids as renal columns called Columns of Bertini.

Each renal pyramid has a broad base towards the cortcal side. Apex is pointed and is called renal papilla. 1 – 3 renal papillae project into a cavity called minor calyx, which join up and form major calyces. Interstitial fluid of medulla region has a higher osmotic concentration equal to some 1200 mOsm/L due to higher quantity of two solutes, NaCl and urea. Cortical region close to medulla is called juxtamedullary area. The major calyces open into a broad funnel shaped structure called renal pelvis placed inner to hilum. It is lined by transitional epithelium. It leads into the ureter.