Renal Reabsorption Flashcards
what is the normal extracellular sodium concentrations
133-146 mM
what is the normal extracellular potassium concentrations
3.5-5.3 mM
what is the normal intracellular sodium concentrations
10-12 mM
what is the normal intracellular potassium concentrations
140-155 mM
what is the normal extracellular calcium concentrations
2.1-2.6 mM
what is the normal intracellular calcium concentrations
10(-7) M
what is the normal extracellular chloride concentrations
95-108 mM
what is the normal intracellular chloride concentrations
4.2mM
what is transcellular reabsorption
where substances move through the cell wall (e.g. through transporters)
what is paracellular reabsorption
where substances move between cells due to concentration gradients
what is the primary active transporter in the nephron
the sodium potassium ATPase
what does the sodium potassium ATPase do
pump 3 sodium out and 2 potassium in
where does sodium uptake in the nephron occur
in the ascending loop of Henle, distal convoluted tubule, collecting duct, proximal convoluted tubule
how is sodium reabsorbed in the loop of Henle
NKCC2 - cotransporter transports sodium, potassium and chloride in
how is sodium reabsorbed in the DCT
NCCT - sodium and chloride co transporter
ENaC - epithelial sodium channel
what drug blocks NCCT
thiazides
what drug blocks ENaC
amiloride
how is sodium reabsorbed in the collected duct
ENaC
what percentage of bicarbonate ions are reabsorbed in the kidneys
100%
where is bicarbonate reabsorbed
proximal convoluted tubule
describe bicarbonate reabsorption
the sodium hydrogen exchange allows sodium in and hydrogen out. the hydrogen combines to make carbonic acid which then splits into carbon dioxide and water. the carbon dioxide moves back into the luminal cell and helps form bicarbonate which is take. up by an anion exchanger
how is water reabsorbed in the collecting duct
through aqua porins
what hormone increases the expression of aqua porins
anti diuretic hormone
what do diuretics do
block sodium reabsorption to give a loss of sodium and water in the urine
how much sodium is reabsorbed
99%
through what transporters is water reabsorbed
aqua porins
what hormones controls the expression of aqua porins
anti diuretic hormone
why can reabsorption occur in the nephron
the luminal and basolateral surfaces of the epithelia lining the tubules are polarised
through which transporters is glucose absorbed into the epithelia from the lumen
sodium glucose transporter 2
what transporter takes glucose from the epithelia to the blood
GLUT 2 transporters
at what plasma glucose levels are the glucose transporter saturated
11 mmol/L
what happens when all the glucose transporters are saturated
glucose is lost into the urine
how is phosphate reabsorbed
through a sodium dependant transporter
how are amino acid reabsorbed
through a sodium dependant transporter
how is urea reabsorbed
through a sodium dependant transporter
how is albumin reabsorbed
RME
how are vitamins B12 and D3 reabsorbed
RME
how is calcium reabsorbed
once it enters the epithelia, a vitamin D receptor then activates it to be reabsorbed into the blood
which part of the nephron reabsorbs the most sodium
PCT
what channels are found in segment 1 of the PCT
NHE
Na glucose symport
Na-Pi co-transporter
Na-AA co-transporter
what is pressure natriuresis
where sodium is lost in the urine due to an increase in pressure
what is pressure diuresis
where more water is lost in the urine due to an increase in pressure
what transporters are found in segments 2 and 3 of the PCT
NHE
what drug blocks NHE
amiloride
what is reabsorbed in the descending limb of the loop of henle
water
what transporters are found in the descending limb of the loop of Henle
aqua porins 2,3 and 4
what is reabsorbed in the ascending limb of the loop of henle
sodium
what channels are found in the ascending limb of the loop of henle
NKCC2 and ROMK
what channels are in the early DCT
NaCl symporters
what channels are found in the late DCT
ENaC
what are NaCl sensitive to
thiazide diuretics
what are ENaC sensitive to
amiloride
what 2 cell types are found in the collecting duct
principal cells and intercalated cells
what do principal cells do
reabsorb Na through ENaC channels
what do intercalated cells do
secrete H+ or bicarbonate to alter blood pH
what drives the movement of chloride ions throughout the nephron
the electrical gradient set up by the movement of sodium allows a passive paracellular movement of chloride
