new_n_lost
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Aldosterone increases Na+ absorption and the negative intratubular potential. It also increases luminal membrane permeability to potassium and stimulates basolateral Na+/K+/ATPase, causing increased urinary potassium losses. Because aldosterone also directly stimulates the proton pump, aldosterone deficiency or resistance would be expected to cause hyperkalemia and acidosis.
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| new_n_lost
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Hyperkalaemia is due not only to reduced urinary excretion, but also to potassium release from cells—either as a consequence of cell death or as a result of metabolic acidosis.
Its a multitude effect on the Kidney in any form of Acidosis AS always its all inter- related there has to be a reason for everything. Initially anything which changes the content of Potassium content in the body will result in high K excretion. conversely low excretion when the feedback is inhibited. Just Remember in the Kidney the only thing maintaining ur K ion is the presence of Na ion. Since Na+ is also reabsorbed in association with H+ secretion, there is competition for the Na+ in the tubular fluid. K+ excretion is decreased when the amount of Na+ reaching the distal tubule is small, and it is also decreased when H+ secretion is increased. When total body K+ is high, H+ secretion is inhibited, apparently because of intracellular alkalosis; K+ secretion and excretion are therefore facilitated. Conversely, the cells are acidic in K+ depletion, and K+ secretion declines. Apparently the K+ secretory mechanism is capable of "adaptation," because the amount of K+ excreted gradually increases when a constant large dose of a potassium salt is administered for a prolonged period.
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| clementjincy
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hi ,
new_n_lost ,thanks for the explanation.......bt i am kind of lost....
can u pl explain a bit more clearly.......
acute acidodis......decreased pot excreation...why.?
in ch. it increases?
what i know is.....
in acido there is hyperkalemia and filtered load of pot in high.....and when it reaches distal tubule, again pot is secterted into the tubule in exchange of Na?
and also the negetive charge in the lumen attracts the pot......
so more of pot secreated?
and later on when kidney has to compensate for this acidosis, it stasts secreating more and more H+ ions, which will neutralise the negative intraluminal charge.......
so pot excreation is decreased.....this is what i under stood....
in kaplan physio,chapter 3 of renal....there is a small table givan....
pl anyone explain...thanks alot
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| new_n_lost
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The Normal mechanism in Acidosis is for the Kidney to decrease Secretion of K ions right that part is easily understood. Now considering that original cause of Acidosis still exists n further hampers the potassium uptake by the Cells which Leads to further decrease in K uptake by the cell. Acidosis raises serum potassium by ion transfer out of cells and interference with renal excretion. Hypoxia causes hyperkalaemia by impaired uptake of potassium from extracellular fluid. So in the GFR K ion is more increased than normal n the kidney reacts to preserve the H ion concerntration n thus leading to more loss of K ion even though there is more of acidosis rather than alkalosis. Acidosis of any type is resultant of the increased K dynamics. If can Find the Cause of Acidosis then u can easily understand how the K ion is effected
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| Sayulita
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cool
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| clementjincy
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okey.....thanks a lot.....
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| SmokyWaters
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wel clement.. I dunno if you get this or not...but lemme try too :P
here is it...
H ions are positive charged and K ions are positive charged as well..when there is ACIDOSIS...K leaks MORE than usual from the cells ...
so it causes HYPERKALEMIA...so more excretion of K from kidneys in Glomerular filterate...this K is exchanged with H ions ACTIVELY...more H ions excreted...and more K preserved...
so K excretion is decreased..
while if in case of chronic acidosis...these K H ATPase pump protein is down regulated as a part of homeostasis due to unknown mechanism.....and K is excreted more...as it cant be exchanged ...
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| goodies
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the whole Na, H, and K movement really confuses me. do H and K usually move in the same or opposite directions? i thought that when you reabsorb Na, then you secrete H and K. and when you secrete Na, then you retain H and K? is that wrong? for some reason, i have been able to get all questions right using this kind of generalization, but it sounds like i might be wrong. PLEASE explain!
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