Each nephron consists of four main parts :-
(1) Bowman capsule
(2) PCT (Proximal Convoluted Tubule)
(3) DCT (Distal Convoluted Tubule)
(4) Loop of Henle
(1) Bowman's capsule :-
- Located in the cortex part of kidney.
- Internally lined by simple squamous epithelium which is divided into two layer - outer parietal layer and inner visceral layer.
- The space in between these layer is called capsular space, into which the blood gets filter.
- In the concavity of bowman's capsule located a bunch of capillary called glomerulus.
Glomerulus + Bowman's capsule = Malpighian body / Renal corpuscle
- Blood in glomerular capillary has to pass through the filtration bed, so that it can reach the capsular space.
- This filtration bed is made up of three main layers :-
(i) Endothelium of capillary - A type of simple squamous epithelium.
(ii) Basement layer includes basement membrane of capillary and basement membrane of visceral layer.
(iii) Cells of visceral layer of bowman's capsule.
• At the basement of visceral layer some modified cells are present.
(A) Mesanglia cell :- They help in phagocytosis.
(B) Podocytes / food shape :- These cells have projection called canaliculi which get arranged in such intricate manner that they result in formation of slit pores / filtration slits.
(2) PCT :-
- Located in cortex part of kidney.
- Internally lined by brush bordered cubical epithelium (it has large no. of microvilli which increase the surface area).
- PCT caused maximum reabsorption and secretion of substances, active as well as passive.
- Cells of PCT are also rich in mitochondria and store large amount of glycogen granules.
(3) Loop of Henle :-
- Located in medulla part of kidney.
- Consists of a descending limb and as ascending limb.
- Descending limb has a longer thin segment but ascending limb has longer thick segment.
- Thin segment is internally lined by simple squamous epithelium but thick segment lined by simple cubical epithelium.
- Loop of Henle can only cause reabsorption of H2O in blood. So longer is the loop of Henle more will be the conservation of H2O.
DCT -
- located in cortex part of kidney.
- Like PCT, it also cause reabsorption and secretion.
- Internally lined by brush bordered cubical epithelium but no. of microvilli are very less as compared to proximal convoluted tubule(PCT).
- Cells of DCT also have few mitochondria and store some glycogen granules.
- DCT open into collecting tubule which further opens into collecting duct.