docdoc9 wrote:
D.Phosphate
Correct answer is D.
Clearance of a substance will change with increasing plasma concentration if that substance is secreted or reabsorbed by facilitated mechanism.
As the concentration of the substance increases, the transporter becomes saturated, and its contribution to excretion changes, changing the clearance.
If the substance is reabsorbed by facilitated mechanism, clearance will eventually increase with increasing plasma concentrations.
Approximately 80% of filtered phosphate is reabsorbed in the proximal tubule by a Na-phosphate cotransporter,which is a facilitated mechanism.
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| taipei817
Forum Junior
Topics: 2
Posts: 78
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if glucose were filtered in a healthy individual, all will be reabsorbed. as a result, the clearance for glucose is zero, the body hasnt gotten rid of any glucosein the urine. JR: dont quite understand your explanation.
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| maoudoody
Forum Elite
Topics: 23
Posts: 435
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he said if u saturated the transporters so clearance will increase cause actually u will be losing more substance from the plasma
so we can say that for substance with high clearance like pah or creatinine if u icrease their conc in plasma we r actually saturating their transporters and so a portion will not be secreted so clearance decreses
the opposite is for substances that r reabsorbed like glucose or phosphate
the increses in their concentration will reach a level where the transporters r saturated so we will lose glucose or phosphate and thus the clearance increases but wont reach that of inulin
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