Lecture 22: Renal histology Flashcards
Cortical nephrons
Glomeruli empty into peritubular capillary networks
Short loops of Henle-do not extend deep into medulla
Juxtamedullary nephrons
Glomeruli empty into vasa recta
Long loops of Henle extend deep into medulla
Sequence of branches of the renal artery
Interlobar arteries Arcuate arteries Interlobular arteries Afferent arterioles Gomeruli Efferent arterioles Vasa recta or peritubular capillaries Interlobular veins Arcuate veins Interlobar veins Renal vein
Glomerulus is a
Capillary bed inserted between two arterioles
Afferent and efferent arterioles
Efferent arteriole of glomerulus feeds into either
A capillary loop- the vasa recta
A capillary network- the peritubular capillaries
Renal corpuscle glomerulus includes
Afferent arteriole w/juxtaglomerular cells (secrete renin)
Efferent arteriole
Renal corpuscle Bowmans capsule structure
Parietal layer- outer layer- simple squamous continuous with epithelium of proximal convoluted tubule
Visceral layer- inner layer of podocytes in contact with endothelium of glomerular capillaries
Bowmans space
Located between parietal and visceral layers and is continuous with the lumen of the proximal convoluted tubule
Renal corpuscle is involved in
Producing a filtrate of blood
Intraglomerular mesangial cells
Located between nearby capillaries in the glomerulus and cover endothelium not covered by podocytes
Extraglomerular mesangial cells
Located between the afferent and efferent arterioles at the vascular pole and are associated with the juxtaglomerular apparatus
Mesangium characteristics
Contractile- utilize cytoskeletal contractile proteins to modify blood flow through glomerular capillaries
Phagocytic- take up worn out glomerular basal lamina for recycling and phagocytize immunoglobulins
Proliferative
Mesangium functions
Synthesize matrix and collagen
Secrete prostaglandins and endothelins
Respond to angiotensin II
Provide mechanical support and regulate blood flow
Macula dens
Found at the thick ascending limb-distal convoluted tubule junction
Cells of macula densa are in contact with extraglomerular mesangial cells
Signals renin release from juxtaglomerular cells
Involved in fluid-electrolyte balance and BP regulation
Juxtaglomerular apparatus components
Macula dnesa
Extraglomerular mesangial cells
Juxtaglomerular cells
Juxtaglomerular cells
Associated with macula densa and afferent arteriole
Secrete renin into blood when stimulated by macula densa
Innervated by sympathetic nerve endings which cause increased renin release
Components or renal tubule, in order
Proximal convoluted tubule (First part)
Descending limb of Henle (w/thick and thin portions)
Loop of Henle
Ascending limb of Henle (w/thick and thin portions)
Distal convoluted tubule (continuous w/collecting duct)
Renal filtration barrier components
Fenestrated endothelium of capillaries
Basal lamina
Filtration slits created by adjacent pedicels of podocytes
Selectivity of renal filtration barrier
Water, glucose and most ions pass through
Proteins are typically excluded
Molecules with a large negative charge are excluded
Characteristics of proximal convoluted tube
Simple cuboidal epithelium Apical tight junctions and brush border Basolateral infoldings Basal striations w/abundant mitochrondira Eosinophilic cytoplasm Large, pale staining nuclei
Functions of proximal convoluted tubule
Reabsorb most of filtrate, including water
Remove essentially all glucose and amino acids from filtrate
Reabsorb most sodium and chloride ions
Contains transporters, cotransporters, channels, exchangers
Thick segment of loop of Henle epithelium
Simple low cuboidal
Thin segment of loop of Henle epithelium
Simple squamous
Ascending limb of Henle is _____ to water
Ascending limb is IMPERMEABLE to water
Function of loop of Henle
Descending thin limb is permeable to water, Na+, Cl-
Ascending thin limb is impermeable to water and actively pumps Cl- out, allowing Na+ to follow
Major function is to establish counter-current exchange system which creates osmotic forces necessary to pull water out of distal convoluted tubule and collecting duct in presence of ADH
Distal convoluted tubule characteristics
Smaller cells than proximal convoluted tubule
Larger lumen than PCT and no brush border
Cytoplasm is less eosinophilic than the PCT
Impermeable to water except in presence of ADH
Principal cells
Found in collecting duct
Reabsorb sodium ions and water and secrete potassium via ATPase pump
Intercalated cells
Found in collecting duct
Secrete either hydrogen ion or bicarbonate ion
Prostatic urethra
Passes through prostate
Transitional epithelium
Highly vascularized with veins and abundant elastic tissue
Membranous urethra
Pseudostratified columnar
Forms external sphincter of bladder
Cavernous urethra
Pseudostratified epithelium w/patches of stratified squamous
