Hisology Of The Kidney Flashcards
Histology of collecting systems
Renal calyces, pelvis, ureter, bladder, most of urethra->urothelium-> transitional epithelium
Stratified squamous->
Cells near basement membrane-> cuboidal
Cells near lumen-> squamous
Shape changes as urothelium becomes distended
Surface specialisations that enable it to resist the toxins and acidic pH
Impermeable so urine can’t leak out and water can’t leak in
Functions of the kidney
Filtration of blood, urine production
Endocrine-> renin
Erythropoietin-> erythrocyte production
Synthetic-> active metabolism of vit D
Vascular system
Supplied by renal artery Anterior and posterior inter lobar Arcuate arteries Inter lobar arteries Afferent arterioles Two capillary systems
Capillary systems
Afferent arterioles (larger diameter) Glomerular capillary bed-> efferent arteriole-> peritubular capillary bed-> associated with proximal and distal tubules At corticomedulary junction efferents also produce vasa recta-> follow loop of henle-> drain into intelobar and accurate veins
Histology of blood vessels
Glomerulus-> fenestrated epithelium
Descending vr-> continuous epithelium
Ascending vr-> fenestrated
Glomerular filtration barrier
Capillary-> fenestrated-> 70nm holes
Basement membrane->collagen, lamin, fibrocontectin! negatively charged glycocalyx
Diaphragm-> covers filtration slits of podocytes-> impermeable to molecules larger than 14nm, contains nephrin
Glomerular disease
Endothelial cells of glomerular tuft may enlarge and proliferate-> blocks cappilaries-> hypertension
Increased blood urea, creatine, oedema
RBCs leak from capillaries in to nephron-> haematuria-> nephritis syndrome
Basement membrane may allow protein through-> protienuria! hypoalbuminemia, oedema
Foot processes may be lost from podocytes-> filtration slits enlarge-> protiens leak out-> minimal change nephropathy-> usually seen in children
Glomerulonephritis and pyelonephritis
Glomerulonephritis-> immunologically mediated damage to glomeruli
Pyelonephritis-> refers to bacterial induced inflammation of renal tissue, usually due to urethra infection
Mesangial cells
Support of capillary loop system
Contract and regulate blood flow
Secrete prostaglandins and agiotensin 2
Phagocytosis
Juxtaglomerular location
Glomerulus is next to ascending limb which crosses the afferent and efferent arterioles and becomes distal tubule
Juxtaglomerular apparatus
Wall of ascending limb-> macula densa cells
Juxtaglomerular cells
Afferent and efferent arterioles
Auto regulation of renal blood flow and GFR-> feedback
Renin producing (myoepithelial) cells:
Regulates plasma volume and BP
Catalysed RAA
Stimulates adrenal cortex to release aldosterone-> regulates sodium and potassium levels
Lacis cells:
Extra glomeruli mesanglial cells
Regulate luminal size of afferent and efferent arterioles
Altria pressure difference and filtration capacity
Macula densa:
Different epithelial lining
Nuclei more lumenally placed
Golgi facing vascular pole
Act ass sensors of Na and Cl levels
Can communicate with the extra glomerular cells-> help maintain BP
Proximal convoluted tubule histology
Cuboidal/columnar epithelial cells
Luminal brush border, long micro villi
Basal and lateral interdigital ions between cells
Tight junctions at luminal side of lateral border
Loop of henle
Begins and ends with thick walls
Simple squamous
Non specific cytoplasm
Distal tubule
Cuboidal epithelium
Sparse microvilli
Central nuclei
Rich in mitochondria
Collecting duct
Cuboidal epithelium in collecting tubules becomes taller and columnar in ducts
