1.

Explain nephron

Answer» It is the functional unit of kidney
*A kidney is composed of an enormous number of\xa0uriniferous tubules. They are also known as\xa0nephrons\xa0or\xa0renal tubules\xa0or\xa0kidney tubules.Nephrons are the structural and functional units of the kidney.Each kidney is formed of about 1 million nephrons.Nephrons are held together by a connective tissue*.Structure of nephron:Each nephron is made of a glomerulus and a renal tubule.Glomerulus:It is a\xa0tuft of anastomosing blood capillaries\xa0formed by the fine branches of the\xa0afferent arteriole.\xa0These capillaries of the glomerulus again unite to form the\xa0efferent arteriole.The afferent arteriole is wider than the efferent arteriole.The afferent arteriole brings blood into the glomerulus, while the efferent arteriole collects blood from the glomerulus.Renal Tubule:The renal tubule comprises the following regions:Bowman’s CapsuleThe Bowman’s capsule lies in the cortex.It is a thin double-walled, cup-like depression.It is the blind end of the nephron.The glomerulus is located in the concave depression of the Bowman’s capsule.The Bowman’s capsule and the glomerulus together are called Malpighian Capsule or Renal Capsule.The outer layer of the Bowman’s capsule is made of flattened epithelial cells.The inner layer is in close contact with the glomerulus and bears special cells called podocytes.Podocytes have many feet-like processes called pedicels and minute slit-like pores called slit pores. Proximal Convoluted Tubule (PCT)PCT lies in the\xa0cortex.It is also known as the\xa0first convoluted tubule.The Bowman’s capsule continues into the PCT.It is lined with a layer of columnar epithelial cells.The columnar cells are with numerous microvilli to increase the surface area of absorption. Loop of HenleIt lies in the\xa0medulla.It is U-shaped.It is not convoluted.It has a descending limb and an ascending limb.Each limb has a thick region towards the cortex and a thin region towards the medulla.Thick regions are lined with columnar epithelial cells.Thin regions are lined with flat epithelial cells. Distal Convoluted Tubule (DCT)It lies in the\xa0cortex.Its short terminal part is called a collecting tubule.The collecting tubule opens into the\xa0collecting duct.DCT in lined with ciliated columnar epithelial cells.The\xa0collecting duct\xa0receives the contents of many renal tubules.The\xa0collecting duct\xa0is a larger duct which receives collecting tubules of several nephrons.Collecting ducts pass into the renal medulla and join with each other to form the\xa0ducts of Bellini.The ducts of Bellini run through the renal pyramids and open into calyces.All calyces open into the pelvis.From the pelvis, urine is carried to the urinary bladder through the ureters.


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