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Urinary System
N/A
49
Histology
Undergraduate 4
04/21/2012

Additional Histology Flashcards

 


 

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Term
erythropoietin (EPO)
Definition
secreted by kidneys; acts on erythrocyte progenitors in bone marrow and regulates RBC formation in response to decreased O2 conc.; produced by endothelial cells of peritubular capillaries in renal cortex; used to treat severe anemia
Term
renin
Definition
produced by juxtaglomerular cells in kidney; acid protease involved in control of blood pressure and blood volume; cleaves circulating angiotensin to release ANGIOTENSIN I
Term
kidney capsule
Definition
connective tissue covering kidney surface; two distinct layers: outer layer of fibroblasts/collagen fibers & inner layer of myofibroblasts
Term
medullary rays
Definition
section cut through kidney cortex at angle perpendicular to surface reveals series of vertical striations that emanate from medulla; each ray contains straight tubules of nephrons and collecting ducts; one ray with collecting duct for group of nephrons that drain into that duct constitutes RENAL SECRETORY UNIT
Term
cortical labyrinths
Definition
regions bet. medullary rays; contain renal corpuscles, convoluted tubules of nephrons, and colecting tubules
Term
uriniferous tubule
Definition
each nephron and its collecting tubule which connects to a collecting duct in the medullary ray
Term
vasa recta
Definition
capillary network in medulla that runs in parallel with the tubules; represent vascular part of countercurrent exchange system that regulates the concentration of urine; efferent arterioles from corpuscles descend into medullary pyramid - ARTERIOLAE RECTAE, make hairpin deep in medullary pyramid, ascend as VENULAE RECTAE
Term
medullary pyramid
Definition
tubules in the medulla collectively form these conical structures; caused by tubules' arrangement and differences in length; usually 8-12 in human kidney; bases face cortex, apices toward renal sinus; divided into outer/inner medulla; outer medulla subdivided into outer/inner stripes
Term
renal columns
Definition
caps of cortical tissue that lie over pyramids, extend peripherally around lateral portion of pyramid; components of cortical tissue, yet considered medullary;
Term
kidney lobes
Definition
reflect number of medullary pyramids (1 pyramid=1 lobe); subdivided into lobules consisting of a central medullary ray and surrounding cortical material;
Term
nephron
Definition
fundamental structural and functional unit of the kidney; about 2 million per kidney; production of urine; collecting ducts responsible for final concentration of urine;
Term
renal corpuscle
Definition
beginning of the nephron; consists of glomerulus
Term
glomerulus
Definition
tuft of capillaries composed of 10-20 capillary loops, surrounded by Bowman's capsule; glomerular capillaries produce GLOMERULAR ULTRAFILTRATE; supplied by an AFFERENT ARTERIOLE and drained by EFFERENT ARTERIOLE
Term
Bowman's capsule
Definition
double-layered epithelial cup surrounding glomerulus; initial portion of nephron
Term
distal convoluted tubule
Definition
in cortical labyrinth; connects to collecting tubule, often through a connecting tubule, forms uriniferous tubule; 1/3 length of PCT; reabsorption of Na+, bicarbonate; secretion of K+, H+ (acidification of urine), ammonium
Term
order of nephron tubular segments
Definition
proximal convoluted tubule, proximal straight tubule, thin descending limb (including hairpin turn of loop of Henle), thin ascending limb, distal straight tubule, distal convoluted tubule
Term
renal papilla
Definition
apex of medullary pyramid; papillary ducts open into MINOR CALYX on AREA CRIBROSA of papilla.
Term
endothelium of glomerular capillaries
Definition
numerous fenestrations; large number of aquaporin water channels that allow fast movement of water through epithelium
Term
glomerular basement membrane (GBM)
Definition
thick basal lamina; product of endothelium/podocytes of visceral layer of Bowman's capsule; PAS prominent; mostly type IV collagen, proteoglycans, mutiladhesive glycoproteins; LAMINA RARA EXTERNA, LAMINA RARA INTERNA, LAMINA DENSA
Term
visceral layer of Bowman's capsule
Definition
podocytes, visceral epithelial cells; podocytes extend processes around capillaries - PEDICELS; pedicels interdigitate with one another, spaces between - FILTRATION SLITS
Term
filtration slit diaphragm
Definition
ultrathin zipper-like sheet that spans the filtration slits of pedicel interdigitation; NEPHRIN - transmembrane protein, key structural/functional component of slit diaphragm; nephrin molec's from opposite pedicels interact in center of slit
Term
glomerular filtration barrier
Definition
endothelium of glomerular capillaries, visceral layer of Bowman's capsule, glomerular basement membrane, endothelial surface layer (glomerular capillaries), subpodocyte space; active structure that can remodel and modify permeability - not passive
Term
parietal layer of Bowman's capsule
Definition
parietal epithelial cells forming simple squamous epithelium;
Term
Bowman's space
Definition
space between visceral and parietal layers of Bowman's capsule; receptacle for the glomerular ultrafiltrate produced by the filtration apparatus of the renal corpuscle; continuous with proximal convoluted tubule
Term
mesangium
Definition
mesangial cells + their ECM; enclosed by GBM; phagocytosis/endocytosis - removed residues, immune complexes from FSD; structural podocyte support (ECM); secretion of molec's in response to glomerular injury; modulation of glomerular distension in response to blood pressure
Term
lacis cells
Definition
mesangial cells located outside the corpuscle along vascular pole; part of juxtaglomerular apparatus
Term
juxtaglomerular apparatus
Definition
includes macula densa, juxtaglomerular cells, and extraglomerular mesangial cells; regulates blood pressure by activating renin-angiotensin-aldosterone system
Term
macula densa
Definition
cells of wall of terminal distal straight tubule; narower, taller than other distabl tubule cells; appear crowded; monitor Na+ concentration in tubular fluid, regulating glomerular filtration rate and renin release; decrease in Na = renin secretion
Term
juxtaglomerular cells
Definition
modified smooth muscle cells of afferent (sometimes efferent) arteriole; contain secretory granules containing renin; circular nuclei
Term
renin-angiotensin-aldosterone system (RAAS)
Definition
maintains Na+ homeostasis and renal hemodynamics; renin released into bloodstream by juxtaglomerular cells, cleaves angiotensinogen to angiotensin I, converted by ACE to angiotensin II, stim's release of aldosterone from zona glomerulosa of adrenal gland and induces vasoconstriction controlling renal and systemic vascular resistnace, increases reabsorption of Na (& H2O) in collecting ducts = increases blood volume/pressure; increase in blood volume and stretching of juxtaglomerular cells may stop renin secretion
Term
glomerular ultrafiltrate
Definition
water, Na, bicarbonate partially reabsorbed ; glucose completely reabsorbed; creatine, organic acids/bases added by secretory activity of tubule cells
Term
proximal convoluted tubule
Definition
receives ultrafiltrate from Bowman's capsule; cuboidal cells with elaborate specializations: brush border, junctional complex, plicae/folds on lateral surfaces, interdigitation of basal processes of adjacent cells; basal striations
Term
amount of reabsorption
Definition
120 L/day out of 180 L/day reabsorbed - approx. 65% ultrafiltrate
Term
Na+/K+-ATPase pumps
Definition
active reabsorption of Na+ (and H2O), passive diffusion of Cl- to maintain neutrality; increase in NaCl in intercellular spaces creates osmotic gradient for H2O, lateral folds separate for distension; cotransport amino acids, glucose for reabsorption
Term
AQP-1
Definition
H2O transmembrane channel protein; does not require high energy of Na+/K+-ATPase pumps
Term
loop of Henle thin segment
Definition
type I epithelium: descending/ascending limbs of short-looped nephrons, no interdigitations, few organelles
type II epithelium: thin descending of long-looped nephrons, taller, abundant organelles, microvilli
type III epithelium: thin descending in inner medulla, thinner epithelium
type IV epithelium: bend of long-looped nephrons & thin ascending, low, flattened, no microvilli
Term
loop of Henle:
thin descending limb
Definition
highly permeable to water, much less permeable to solutes (NaCl, urea); PASSIVE movement of H2O into peritubular CT, no ion transport
Term
loop of Henle:
thin ascending limb
Definition
highly impermeable to water; no active ion transport; highly permeable to NaCl - passive diffusion into interstitium; Cl- diffuses into interstitium across gradient via Cl- channels, Na+ K+ follow; cells produce UROMODULIN
Term
uromodulin
Definition
produced by thin ascending loop epithelial cells; influences NaCl reabsorption and urinary concentration ability
Term
distal straight tubule (thick ascending limb)
Definition
electroneutral synporters transport Cl-, Na+, K+ into cell; large cuboidal cells with indistinct lateral margins; nuclei at apical portion, bulges into lumen; extensive basolateral plications with many mitochondria
Term
light cells/collecting duct cells
Definition
principle cells of collecting tubules/ducts; single cilium; small, spherical mitochondria; abundance of ADH; aquaporin-2 channels
Term
dark cells/intercalated cells
Definition
small numbers in collecting tubules/ducts; many mitochondria; microplicae on apical surface (mistakable for microvilli); secrete H+ or bicarbonate depending on needed pH;
Term
interstitial tissue
Definition
cortex: cells that resemble fibroblasts, occasional macrophages
medulla: cells that resemble myofibroblasts
Term
countercurrent multiplier system
Definition
allows excretion of hyperosmotic urine; LOOP OF HENLE (multiplier; osmotic gradients established along axis of loop), VASA RECTA (exchangers of water/solutes; loops parallel to loop of Henle, maintains osmotic gradient of medulla), COLLECTING DUCT (osmotic equilibrating device; depneds on ADH-dependent AQP-2
Term
countercurrent multiplier effect
Definition
NaCl conc. in interstitium gradually increases down length of LOH and through thickness of medulla from corticomedullary junction to papilla
Term
countercurrent exchange system
Definition
both arterial and venous sides of vasa recta loop are thin-walled vessels forming plexuses of fenestrated capillaries in medulla. descend - blood loses H2O to interstitium, gains salt; ascend - loses salt, gains H2O
Term
peritubular capillary network
Definition
efferent arterioles of renal corpuscles in cortex branch to form capillary network surrounding tubular portions of nephron in cortex
Term
ADH
Definition
when present, distal convoluted tubules, collecting tubules, and collecting ducts are highly permeable to water
Term
organization of kidney blood supply
Definition
renal artery into each kidney; banches in renal sinus to INTERLOBAR ARTERIES; travel bet. pyramids, turn and follow arched course at pyramid base bet. medulla/cortex - ARCUATE ARTERIES; branch into INTERLOBULAR ARTERIES, ascend toward capsule; branch into AFFERENT ARTERIOLES; after glomerulus, EFFERENT; then peritubular capillaries
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