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Terms in this set (53)

Most water & solutes are recovered by the blood (i.e. 179/180 L reabsorbed), leaving only a small volume of tubule fluid left to move on to the Henle loop.
1) Sodium --> ACTIVELY transported out of tubule fluid & into blood... As Na ions accumulate in the interstitial fluid, it creates an electrical gradient that drives the diffusion of negative ions from the filtrate, into the interstitial fluid, and eventually, into the peritubular blood. Thus, it drives transport of Cl-, phosphate (PO4) and other negative ions out of the tubule.
2) Glucose & amino acids --> PASSIVELY transported out of tubule fluid by "sodium cotransport" (facilitated diffusion) mechanisms (They HITCH A RIDE with Na); transport maximum (Tm or Tmax) is the maximum capacity of reabsorption & depends on # of cotransport carrier availability. VERY little glucose is lost in urine. Almost ALL of it is reabsorbed... unless the blood glucose level was really high, then excess remains in urine. "Glucose rides the coat-tails of sodium".
3) Chloride, phosphate, & bicarbonate ions --> PASSIVELY move into blood because of an imbalance in electrical charge (positive Na ions have already moved out, thus making plasma positive & the tubule fluid negative)
4) Water --> movement of sodium & chloride into blood causes an osmotic imbalance (blood hypertonic to filtrate), moving water passively into blood, thus making the two fluids isotonic.
5) Urea --> approx. half of urea PASSIVELY moves out of the tubule with the remaining half of urea moving on to the Henle loop