− | Transport capacity is well above what is needed for normal plasma concentrations to ensure that adequate absorption occurs and that there is little/no wastage. As you are getting transport of sodium, chloride and water simultaneously the concentration does not increase along the proximal tubule. However the volume of filtrate does decrease | + | Transport capacity is well above what is needed for normal plasma concentrations to ensure that adequate absorption occurs and that there is little/no wastage. As sodium, chloride and water are reabsorbed at the same rate, the filtrate concentrations remains the same along the proximal tubule. Only the volume of the filtrate decreases. |