CHAP 15: DIURETICS Flashcards
what is diuretics
increase production of urine
or
increase the amount of water and salt expelled from the body as urine
what is natriuretic
increase in renal sodium excretion
what is aquaretic
increase excretion of solute free water
what do you call these agents result in increased urine output and increased urea excretion but not increased excretion of electrolytes.
aquaretics
Sodium bicarbonate (NaHCO3), sodium chloride (NaCl),
glucose, amino acids, and other organic solutes are reabsorbed via specific transport systems in the early proximal tubule
sodium bicarbonate, sodium chloride co-transporter
potassium ions are reabsorbed via?
paracellular pathway
what channel absorbs water passively
through a transcellular pathway ( aquaporin-1 [AQP1])
and
paracellular pathway (claudin-2)
As tubule fluid is processed along
the length of the proximal tubule, the luminal concentrations of most solutes decrease relative to the concentration of ____, an experimental marker that is filtered but neither secreted
nor absorbed by renal tubules.
inulin
approximately __% of filtered sodium ions, __% of the NaHCO3, __% of the potassium, __% of water and virtually all of the filtered glucose and amino acids are reabsorbed by the proximal tubule in normal
humans
66%
85%
65%
60%
drug that blocks sodium bicarbonate (NaHCO3) reabsorption in the proximal tubule
carbonic anhydrase inhibitors
sodium bicarbonate (NaHCO3) reabsorption by the PCT is initiated by the action of
sodium hydrogen exchanger
Na+/H exchanger (NHE3)
where does sodium hydrogen exchanger located
in the luminal membrane of the proximal tubule epithelial cell
function of sodium hydrogen exchanger
allows Na+ to enter the cell from the tubular lumen in exchange for H+ proton from inside the cell
sodium in, hydrogen out
why does the body need to pump Na+/K-ATPase in the basolateral membrane?
to maintain a low intracellular Na concentration
hydrogen is secreted into the lumen and combines with bicarbonate to form?
carbonic acid
on the lumen, the carbonic acid is rapidly dehydrated to ___ and ___ by ___
carbon dioxide and water by carbonic anhydrase
Carbon dioxide produced by dehydration of carbonic acid enters the proximal tubule cell by what diffusion?
simple diffusion
carbon dioxide is rehydrated back to carbonic acid by what enzyme?
intracellular carbonic anhydrase
after dissociation of carbonic acid in the PCT, the hydrogen is available for transport by what exchanger?
and the HCO3 or bicarbonate is transported out of the cell by what transporter?
sodium hydrogen exchanger (NHE3)
basolateral membrane transporter
bicarbonate reabsorption by the proximal tubule is dependent on what enzyme activity?
carbonic anhydrase
what drug can inhibit carbonic anhydrase
acetazolamide
where can we find the Na/K ATPase in the PCT?
in the basolateral membrane
purpose?
to maintain intracellular sodium and potassium levels within the normal range
a cotransporter that is responsible for reabsorbing much of the glucose that is filtered by the glomeruli?
sodium-glucose cotransporter SGLT2
what disease is approved in treating diabetes mellitus in blocking SGLT2?
diabetes mellitus
in what part of the PCT does it secrete organic acids such as uric acid, NSAID, diuretics, etc.
in the middle third
of the straight part of the proximal tubule (S2 segment).
organic base secretory system of PCT is located in what segment of the PCT
early S1 and middle S2 segments of the proximal tubule
transporter or organic acid and base in PCT
acid transport and base transporter
___ is extracted from the descending limb of this loop by osmotic forces found in the hypertonic medullary interstitium
water
thin ascending limp is relatively ___ impermeable but is permeable to some sloutes
water impermeable
function of thin ascending limb?
passive reabsorption of water
transporter found in thin ascending limb?
aquaporins
thick ascending limb reabsorbs ___ from the lumen
NaCl sodium chloride
nearly impermeable to water
thick ascending limb
why is thick ascending limb called a diluting segment?
because salt reabsorption dilutes the tubular fluid
The NaCl transport system in the luminal membrane of the TAL
Na+/K+/2CL+ cotransporter (NKCC2 or NK2CL)
term called for diuretic agents that blocks NKCC2 transporter
“loop” diuretics
since NKCC2 contributes to excess potassium accumulation within the cell. what do you call the channel for potassium to diffuse back into the tubular lumen?
ROMK channel
Renal Outer Medullary Potassium channel
back diffusion of potassium into the tubular lumen causes?
causes a lumen positive electrical potential that provides the driving force for reabsorption of magnesium and calcium via paracellular pathway
only 210% are filtered NaCl is reabsorbed
DCT
primary transporter in the luminal membrane
NKCC2
primary sodium and chloride transporter in the luminal membrane
(NCC) Na / Cl transporter
sodium chloride cotransporter
is there a lumen positive potential in the DCT segment?
no. therefore calcium and magnesium are not driven out of the tubular lumen by electrical forces
what ions are actively reabsorbed by DCT epithelial cell?
calcium
what channels are used in actively reabsorbed calcium
apical calcium channel
and
basolateral Na / Ca exchanger
this process is regulated by parathyroid hormone
collecting tubule system connects the DCT to the?
renal pelvis and the ureter
How many % does the collecting tubule system reabsorbs NaCl by the kidney?
2-5%
The final site of NaCl reabsorption
Collecting tubule system
A part of the tubule transport system where it is tightly regulated by the body fluid volume for determining he final Na concentration of urine
Collecting tubule system
A site at which mineralocorticoids exert a significant influence
Collecting system
The most important site of potassium section by the kidney and the site at which virtually all diuretic-induced changes in potassium balance occur
Collecting system
What cells are the major sites of sodium, potassium and water transport
Principal cells and the intercalated cells
