Jan3 M2-Tubular function Flashcards
daily urine production
1.5L
renal perfusion fraction (renal blood flow over cardiac output)
20%
PCT function
most reabso
loop of Henle fct
salty interstitium
CD fct
reabso or secretion of K, Na and acid
reabso (or not) of H2O
secretion def and stuff comes from where
from blood to tubules. from peritubular capillaries
nephron blood flow
AA, glom caps, EA, along nephron, peritub caps, venous drainage
Na in PCT
(60%) Na K ATPase on basolateral side so Na comes in via cotransporters and exchangers on luminal side
water in PCT
(60%) osmotic flow out of tubules via aquaporins or tight junctions (between cells)
glucose in PCT
(99%) via Na-glucose cotransporter (SGLT2) at lumen and via GLUT2 at basolateral
PO4 in PCT
(99%) via Na-PO4 cotransporter
a.a in PCT
(99%) via Na-a.a cotransporter
Ca in PCT
flows down conc gradient
K in PCT
flows down conc gradient in tight junctions
Cl in PCT (2)
flows down conc gradient via Cl-base exchanger (lumen) and Cl-K cotransporter (basolateral)
OR tight junctions
HCO3 in PCT
(90%) via Na-H exchanger
how HCO3 reabsorbed in PCT
- H20 + CO2 in the cell give H and HCO3 via CA and HCO3 enters the body
- NH4 or H+ exit cell via Na-H or NH4 exchanger
- outside, H joins base that exited via Cl base exchanger. Hbase
- Hbase can enter cell and H can separate from base and reexit.
why glucosuria in diabetics
maximal tubular reabsorption (Tmax) is reached. (SGLT2 reaches its max)
glucosuria (3 ex of conditions where it’s seen)
diabetics, normal people with low SGLT2 amount, pregnant woman (pregnancy = high GFR)
2 components of water regulation in the nephron
- high osmotic gradient in medullary interstitium
2. ADH action in CD for aquaporins insertion
tDL fct (t thin T thick)
permeable to water
TAL fct
NaK ATPase on basolateral side. Na out of tubule via Na-K-2Cl cotransporter
loop of Henle other fct
Ca, Mg reabso in tight junctions
loop of Henle channels
baso: NaK ATPase and Cl channel (Cl back in blood)
lumen: Na-K-2Cl cotransporter and ROMK (renal outer medullary K channel) for K out and for cotransporter not to run out of K)
distal tubule 2 main fcts
reabso of Na, Cl and Ca
distal tubule: how Na reabso works
NaK ATPase (baso) and then Na enters with Na channel (lum) or Na-Cl exchanger (lum)
Cl in distal tubule
moves with Na at lumen via Na-Cl exchanger. Cl channel (baso)
Ca in distal tubule
NaK ATPase (baso) drives Na Ca exchanger (baso). Ca enters cell via Ca channel (lum)
hormones and drugs in distal tubule
thiazides act on Na-Cl cotransporter (lum)
PTH acts on Ca channels (lum)
3 cell types in collecting tubules
principal cells, alpha and beta intercalated cells
Na in collecting tubules
principal cells, Na K ATPase (baso) and Na channel (lum) both controlled by aldo
K in collecting tubules
channels (lum andd baso) to let it out of the cell (to tubule or interst)
acid base balance where in the CT
alpha (mainly) and beta intercalated cells
H2O in CT
under ADH control: allows insertion of aquaporins
2 tissue origins of the nephron and cell type + structure of each
ureteric bud (tubule, epithelial) and metanephric bud (glomeruli. endothelium. but podocytes are epith)
