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 help with renal question  



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Author5 Posts
  #1

Hi, I need some help regarding inulin PAH, mannitol, donot completely understand reabsorption filtration and secretion, if someone doesnot mind going into detail regarding this it has me somewhat confused. THANks




  #2

Filitration-plasma that enters kidneys that goes thru Bowmens capsule.
mathematically its GFR times plasma conc.


Secretion- As I understand is what travels from the plasma into the kidney tubules


Reabsorption is what goes from the kidney tubules back to the plasma.
mathematically reabsorbtion =filtration -excretion

Mannitol-Retards Na andH20 reabsorbtion merely because of its osmotic contribution to the tubular fluid(Its NOT reabsorbed)

PAH is used to measure effective renal plasma flow using the formula we all know uv/p.{PAH IS ONLY USED WHEN PLASMA PAH LEVELS ARE
RELATIVELY LOW AND DO NOT EXCEED PAH SECRETORY Tm!

Hope this helps maybe phuluong, ssrpk, or SDK can add something.
By the way ssrpk congrats on your 10,000th post!


  #3

well thnx for tht mjl .....btw it's 1000 posts! grin

ofcourse there is'nt much to add......but tubular transport for most organic substances in PCT except urea shows wht we call transport maximum which can get saturated .


  #4

thank you for your explanantion, you both have helped in clarifying this question, one more thing though, I understand tm transport, so gradient time transport is only for sodium then. Also when calculating for problem solving should you assume that since filtration fraction is 20%. If for example substance x is in plasma , we should asssume that only 20% of this gets filtered . Is that right or wrong. thankyou once again


  #5

well u can assue filtered load to be approx. 20% for a freely filtered substance but it won't be too helpful as ff varies it's not a constant variable (depends upon renal plasma flow)

filtered load= GFR X P





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