10/14 & 16 Flashcards
in general, diuretics decrease bp by
decreasing blood volume by increasing urinary volume
why is carbonic anhydrase not recommended as a front line diuretic?
because of it’s toxicity: decreases K+ and lowering the body pH by wasting HCO3
where does mannitol work?
throughout the entire nephron but primarily in the proximal convoluted tubule
mannitol contributes to the _______ of the urine
osmolality
what kind of diuretic is mannitol?
osmotic
what is an osmotic diuretic?
A drug that is going to affect the osmolality of the fluid that’s in the nephron.
what is osmolality?
the number of dissolved particles that are in a solution.
what is a normal body osmolality?
300mOsm/kg
what is the osmolality of the renal cortex?
300 mOsm/kg
what is the osmolality of the kidney as we descend into the renal medulla?
It increases as high as 1200mOsm/kg
why is the osmolality so high in the renal medulla?
as we’re reabsorbing the sodium, before it gets into the blood stream, it goes into the medulla first.
what is an impermeable solute?
a solute that cannot be reabsorbed from the nephron back into the blood.
how does mannitol work?
It is a sugar alcohol that increases the osmolality of the inside of the nephron. Since it’s more concentrated in the nephron water stays in the nephron and goes into the medulla to be excreted.
what is the s2 segment of the nephron?
The fairly straight portion of the proximal tubule before it reaches the loop of Henle. It has special transporters that can transport much larger substances into the urine.
why don’t we have water leaving in the ascending portion of the loop of Henle? what kind of transport do we have instead?
because this section is water impermeable
Na+ leaving via the NKCC2 pump in order to balance the osmolality in the nephron.
what kind of ion movement happens in the thick ascending limb of the loop of Henle?
NKCC2 pumps Na+, K+ and 2 Cl- INTO the Thick Ascending Limb
K+ leak channels leak K+ OUT of the thick ascending limb into urine
this positive efflux pushes
Ca++ and Mg++ INTO the Thick ascending limb
Na+/K+ ATPase pumping Na+ OUT of the Thick ascending limb
K+Cl- cotransports both OUT of the Thick ascending limb into the interstitium.
which part of the loop of Henle is permeable to water? Which direction does water go?
the descending portion
water leaves the nephron to try and balance out the really high osmolality in the renal medulla
what is moving in/out of the collecting tubule?
water leaves
where do loop diuretics work? How?
the thick ascending limb. It blocks the NKCC2 pump so more sodium stays in the urine. water follows.
which electrolytes get depleted or less absorbed when using loop diuretics?
Na+
K+
Cl-
Mg++
Ca++
what is the difference between loop diuretics and carbonic anhydrase inhibitors?
Loop diuretics don’t effect bicarb
what is toxicity of loop diuretics?
allergic reactions. Loop diuretics are Sulfonamides.
what is the only loop diuretic that is not a sulfonamide?
Ethacrynic Acid
why is there less water movement in the distal convoluted tubule?
because the osmolality in the renal cortex is closer to 300mOsm/kg which is balanced