Urinary System Histology

URINARY SYSTEM A pair of kidneys. → Urinary bladder A pair of ureters. → urethra Functions: Produce, store, eliminate urine Aad-Base balance.. Excretion of metabolic wastes, drugs Secretion of renin, erythropoetin Vit D synthesis Gluconcogenesis. KIDNEYS Two bean shaped, organs in backpart of abdominal cavity. → Capsule: Thin but tough. Dense irregular connective tissue (collagen fibers, fibroblasts, myofibroblasts) → Hilum: Depression medial side of kidney. → Renal Pelvis: Upper dilated part of ureter Parenchyma Renal cortex Renal Medulla Outer reddish brown Inner light pink Granular Striated 90% of blood flow 10% of blood flow Contains renal pyramids → Renal lobe: Each renal pyramid with its associated overlying cortex The neighbouring renal pyramids are separated by renal columns Cextension of cortical tissue into medullary part) Medullary rays. are the longitudinal shiations which radial into renal corter.. Blood Supply of Kidney: Renal artery Segmental arkry Inkrlobor arkry Arwate artery Inkilobular artery Peritubular Capillaries / vasarecta Stellale vein Interlobular vein Arcuate vein Interlobar vein Punal vein PARENCHYMA OF KIDNEY consists of uriniferous tubules Nephrons Collecting duct NEPHRON Chief Structural and functional unit of kidney Long epithelium lined tube Highly tortuous for greater part of its course.. Parts of Nephron → Renal corpuscle/Malpighian corpuscle Glomerulus and Bowmann's capsule → Proximal Convoluted tubule. Highly convoluted part → Proximal Straight tubule (shorter, straight) ج Loop of Henle (Nephron loop) → Distal Tubule Straight (thick part) → Distal convoluted tubule Clong and tortous.) → Connecting tubule (cortical collecting tubule) Classification of Nephrons Superficial Cortical Mid cortical Justunnedullary Renal corpuscles Outer part of cortex Middle part of cortex Loop of Henle Deepest part of cortex Short Intermediate Long Lextend deep into medulla) →Renal Corpuscle: Spherical bodies. 2 poles (vascular pole & urinary pole) Bowmann's Capsule: (Glomerular Capsule) Double walled cup like structure Layers Parietal layer Visceral Layer Outer wall Inner wall Simple squamous epithelium Single layer of Podocytes → space blu parieral and visceral layers is caued urinary/capsular space. Poducytes: Large, irregulary star shaped cells Common basement membrane with glomerular capilla-les Cell bodies give rise to primary processes. Primary process give rise to secondary processes / pedicels/foot processes. Foot processes are sepcuated by neighbouring processes via narrow gaps called filtration slits. Thin membrane covering filbarion slits is called slit diaphragm/slit membrane... Slit diaphragm. contain special prokins called nephrins, Podocalyxin, P-cadherin which allow passage of only Small molecules. Podocycs contain. → Roughly oval nucleus. →I mitochondria, ribosomes, RER... → Microtulbules, actin filaments. Glomerular Basement Membrane: "The basal Lamina of visceral layer of Bowmann's capsule b/w podocytes and endothelial cells. of glomeruker capillaries is called glomerula, basement memb. 3 layers Lamina rara externa Lamina densa Lamina rava intema Electron lucent Electron derse Electron wrent Heparan sulfate, Adhesive glycoprokios Collagen IV Same Composition as of externa Filter on the basis of size, weight, chage Physical slit (sieve like filter) → Heporan sulfate repels rely charged molecules → laminin, fibronectin anchor padocytes to basement memb.. → Glomerulus: Tuft of foresterated capillaries connecting afferent artaide with efferent crtcriole... Glomerular capillaries have I bydrostatic pressure... Endothelich cells of glomerular capillaries have large pores not covered by siet diaptiragoms Lumen is covered by thick glycocalyx coat. Mesangial cells: Irregular shaped cells present. b/w glomerular capillaries contain actin and myosin filaments... These cells and their extracellular matrix is collectively called mesangium. Functions: →Phagocytosis of unwanted macromolecules → Structural support for glomerular capillaries Secretion of cytokines and other substances →Regulation of blood flow. FILTRATION BARRIER Endothelium of glomerular capillanes Glomerular basement membrane. Slit diaphragm covering filtration slit CUNICALS →Proteinuria: Excretion of higher amount of protein in urine → Glomerulonephritis: Inflammation within glomeruli →Polycystic kidney disease: Mutiple, large, fluid filled cysts arising from epithelium of nephron