Transport of stuff besides NaCl Flashcards
what types of things are completely recovered and where?
PT. Glucose, AAs, TCA intermediates
How is glucose recovered?
Apical-electrogenic Na/glucose. Early-1 Na, Late-2 Na
What is normal plasma glucose and what is the threshold (Tm)?What is splay>
5, 15 mM. Gradual transition due to differences in glomerulus size and PT length
How are reuptake of AAs and TCA intermediates different from glucose?
Lower thresholds. Competitive inhibition (eg. ^argenine=decrease lys and orn). Apparent competition due to global dependence on Na gradient (glucose loading).
where does secretion occur?
PST
What is PAH used for and why?
Renal plasma flow b/c it is completely secreted.
What do you do in case of weak acid overdose? why? weak base overdose?
Alkalinize urine. Wk acids are unionized at low pH and can diffuse across membrane. Alkaline tubule causes dissociation and trapping. Acidify urine
What is normal plasma [Pi] and what is the threshold?
.7-1.3; Threshold is just below that. Regulated at upper end by excretion
How is uptake of Pi regulated? Mechanism?
PTH decreases Pi uptake when you need to reabsorb Ca so you dont get precipitation in urine. Apical channel endocytosis.
How is Ca resorbed
Transcellular: apical Ca channel and basolat Na/Ca ATPase. Paracellular: PT-conc gradient. TAL(most important)-lumen potential via Paracellin1
How is Ca regulated? What else is lost?
PTH. ^time apical Ca channels are open. Vit D by unknown mechanism. Paracellular: High Ca leads to closure of apical K channels and Na/K/Cl transporter. Lumen becomes more (-). Concomitant Na loss
effect of Loop diuretics on Ca.
block Na/K/Cl, reduced lumen (+) potential, decreased paracellular Ca flux
effect of thiazide diuretics on Ca
block Na/Cl transport, hyperpolarization, ^ transcellular Ca uptake, reduced Na uptake
effect of Amiloride on Ca
blocks Na channels, hyperpolarize cell, ^ transcellular Ca flow, decrease Na flow
magnesium resorption
paracellular so loop diuretics also interfere with this
