Chapter 23.4, Problem 4AYLO

Summary Introduction

To discuss:

How tubular reabsorption is limited by the transport maximum (T_m); how this relates to glycosuria in diabetes mellitus.                     

Introduction:

In the whole of the glomerular filtrate, about 65% are reabsorbed by the proximal convoluted tubule. The proximal convoluted tubule removes wastes present in the blood and excretes them through the urine. Due to the presence of microvilli (its greater length), the proximal convoluted tubule has the benefits of increasing its surface area for absorption. Proximal convoluted tubule cells are equipped with a rich source of large mitochondria that produce ATP, which supports active transport. Of all the calories that are consumed in a day, only 6% of ATP is needed by the proximal convoluted tubule.