Part II DR IMRANA EHSAN Solute and water reabsorption inLoop of Henley Tubular fluid PCT reabsorbed 65 of the filtered water so chemical composition of tubular fluid in the loop of ID: 600076
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Slide1
TUBULAR REABSORPTION Part II
DR .IMRANA EHSANSlide2Slide3
Solute and water reabsorption
inLoop
of HenleySlide4
Tubular fluid
PCT reabsorbed 65% of the filtered water so chemical composition of tubular fluid in the loop of
Henle
is quite different from plasma since many nutrients were reabsorbed as well,
osmolarity
of tubular fluid is close to that of blood
Sets the stage for independent regulation of both volume & osmolarity of body fluids.THIN DESCENDING LIMB: Highly permeable to water and moderately permeable to solutes.20% of fluid reabsorbed
Reabsorption in the Loop of
HenleSlide5
Symporters in the Loop of Henle
ASCENDING LIMB :
THIN ASCENDING LIMB: impermeable to water.
Thick ascending limb: has Na+ K-
Cl
-
symporters on liminal side that reabsorb these ionsK+ leaks through K+ channels back into the tubular fluid leaving the interstitial fluid and blood with a negative charge Na/Kpump on basolateral
membrane
Ca, Mg, Na ,K passively move to the vasa recta BY PARACELLULAR ROUTE.
info@abl.com.pkSlide6
DESCENDING LOOP OF HENLE: No active transport of salt out of the descending loop of
Henle
.
ASCENDING LOOP OF HENLE: Chlorine ions actively transported out of loop
into the interstitial space
. Oppositely charged sodium ions follow. However,
water does not move out of the ascending loop.A concentration gradient IN THE INTERSTITIAL SPACE has been set up by the chlorine ( plus sodium) transport.Slide7
Early distal convulated tubule:
Reabsorption
on the early distal convoluted tubule
Na
+
-
Cl- symporters reabsorb Na+ and Cl-, Ca,Mg
.
Na/K Pump at
basolateral
membraneNa Cl cotransport on luminal surface Major site where parathyroid hormone stimulates reabsorption of Ca+ depending on body’s needsReabsorption
and secretion in the late distal convoluted tubule and collecting duct
90-95% of filtered solutes and fluid have been returned by now
Principal cells reabsorb Na
+
and secrete K
+
Intercalated cells reabsorb K
+
and HCO
3
-
and secrete H
+
Amount of water
reabsorption
and solute
reabsorption
and secretion depends on body’s needsSlide8
Early distal covulated tubuleSlide9
DISTAL TUBULE AND CORTICAL COLLECTING DUCTSSlide10
Medullary collecting ductsSlide11
Hormonal regulation of tubular reabsorption and secretion
Glomerulotubular
balance
Increased tubular load increases
reabsorption
rates
Angiotensin II - when blood volume and blood pressure decreaseDecreases GFR, enhances reabsorption of Na+, Cl-
and water in PCT
Aldosterone
- when blood volume and blood pressure decrease
Stimulates principal cells in collecting duct to reabsorb more Na+ and Cl- and secrete more K+ Parathyroid hormoneStimulates cells in DCT to reabsorb more Ca2+2
nd
line of
defence
Prevents overloading of distal tubular segmentsSlide12
Fluid flow in pertubular compartment