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36 Cards in this Set
- Front
- Back
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where is Ca found? what is it important for?
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most in bone
More in ICF than ECF Bone, cell division, signaling, blood coagulation, contraction, hormone response couppling |
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what is a normal plasma conc
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2.5mM
**recall more ca in the cell than in plasma |
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how is ca found in the plasma
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1. free
2 with protein 3. with anions |
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how does the state of the Ca aftect if it is filtered or not
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most is free and will be filtered and reabs
**the stuff bound to protein is not filtered and remains in the blood |
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how do we determine filtered load of Ca
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we need to take into account that of the total plasma conc of Ca only 60% is filtered
Fl= (GFR)(P)(0.6) |
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where is Ca reabs, where is it not?
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every but descending limb
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is Ca reabs
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YES!!! 99% reabs
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how is Ca reabs in the PCT
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parracellular,
linked to na, when Na reabs is favored so is Ca reasb |
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when Na reabs is high in the PCT what else is?
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Ca
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what is going on int he thick Ascending limb in terms of transport, what does this do to the charge in the lumen
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Na/K/2Cl, even chagrege
*K leaks back into lumen making is POSTITVE **positive lumen potential *this positive lumen potential drives Ca OUT.of the lumen for reabs |
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what is a unique feature that drives Ca reabs
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the inside of the lumen is + so this favors Ca to leave
Paracellular |
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waht transporters drive Ca reabs in the ascending limb
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NONE, paracellular. Driven by the positive charge in the nephrin lumen
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what diuretic interfers with Ca reabs
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loop diuretics
**loop diuretics used to treat hypercalcemia |
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waht is a weird way to treat hypercalcemia
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loop diuretics.
**they block Ca reabs at the ascending limb |
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in the DCT how is Ca reabs
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1. apical, Ca channels
2. Basolateral -Ca ATPase - Na/Ca exchange |
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wht does parathyroid do
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stim Ca uptake in DCT
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so loop diuretics block Ca reabs, what do thiazide do?
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inhibit NaCL reabs and STIM Ca reabs
*increase Na, and consequently increaes Ca bc of the Na/Ca so transporter transporter on apical side that brings both Na and Ca into the tubule cell for areabs. BLOCKED |
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we give loop diuretics to inhibit Ca reabs, what do we give for increasing Ca reabs
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thiazides
*inhibit the Na/Ca transporter that brings these things across the apical membrane for reabs |
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what is PO4 good for (3)
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urinary bufer
bound to plasma protines bone |
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is PO4 filtered? it is reabs
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sure is
most is, but about 15% isnt bc of its role as a urinary buffer |
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where is PO4 reabs
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PCT
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how much PO4 is excreted
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about 15%
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what transporter in the apical membrane handles PO4? what about basolateral
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in PCT
**3Na/PO4 cotransport to enter the cell and then to leave the cell across the basolateral membrane there are 2 ways 1 Diffusion 2. PO4 anion transporter |
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reabs of PO4 is ties with reabs of what?
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Na
3 Na/PO4 transporter on apical side. |
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when is PTH released? how does it affect PO4 and Ca
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when plasma Ca is low
*stim plasma reabs in LOH and DCT to increase plasma Ca **decreases PO4 reabs in PCT and increase excretion of PO4 we dont want these meeting and forming bone in the kidney/blood |
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when PTH is released Ca is ___ in the ____. PO4 is ____ in the ____
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reabs LOH, DCT
not reabs, PCT |
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what does it mean when PO4 reabs is saturated
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no more can be reabs
*Tm is a little above normal filtered load **with PTH (inhibit PO4 reabs via 3Na/PO4 cotransport) the Tm is decreased |
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how does PTH affect the Tm of PO4
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decreases it
**Tm normally is just above filtered load. PTH blocks reabs of Na and decreases the Tm. Decrease the activity of 3Na/PO4 transporter |
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wht decreases the activity of the 3Na/PO4 tranporter in the PCT
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PTH
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is the kidney th only Mg regulator
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nope, also Bone and GI
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how do we find Mg in the ECF. is much Mg stored in teh ECF
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lots is ionized (FILTRATABLE)
some with anions some with protein Relatively Not lots stored here. about 1.0mM |
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where is Mg stored
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LOTS in bone
in the cell small part in ECF where it is found free, bound to ions, and bound to protein. |
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what is the major site of reabs of Mg
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the ascending limb!!!
weird, most substances are secreted in abundance in the PCT |
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where all is Mg abs
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PCT 30%
ascending limb 60% 5% DCT 5% excreted |
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how is Mg reabs in the ascending limb
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same way as Ca, paracellular driven by a positive lumen
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is ALL Mg reabs
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nope, 5% is secreted
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