All are part of glomerular filtration barrier except

Ans:a (Mesangial cells) Ref: Robins 7th ed/p.957, 958Glomerular filtration barrier consists of the following structures1) Fenestrated endothelial cells2) Glomerular basement membrane (consists of type IV collagen)3) Visceral epithelial cells (podocytes)Mesangial cells are stellate cells located between the basement membrane and the endothelium. They are of mesenchymal origin.Functions of Mesangial cells* Support the entire glomerular tuft* Secrete mesangial matrix* Have contractile function (have role in regulation of glomerular filtration and not as a barrier)* They are phagocytic* Capable of proliferationOther cells in kidneyPrincipal cells - found in collecting ducts, concerned with Na reabsorption and vasopressin stimulated water reabsorption.Intercalated cells - found in collecting ducts, concerned with acid secretion and HC03 transport.NoteEach kidney contains -1 million nephronsPCT- 15 mm longDCT- 5 mm longNormal GFR-125 ml/minInulin and creatinine are used to measure GFR.PAHA (P- amino hippuric acid) is used to measure renal plasma flow.