Give a reason why glucose does not normally appear in urine even though its filtered in mammalian bowman's capsule
One reason why glucose does not normally appear in urine is because it is efficiently reabsorbed by the renal tubules. After filtration in the Bowman's capsule, glucose is quickly reabsorbed back into the bloodstream through specialized glucose transporters present on the apical membrane of the renal tubular cells. These transporters actively transport glucose from the tubular lumen into the tubular cells, and then it is transported out of the tubular cells into the peritubular capillaries. This reabsorption prevents the glucose from being excreted in urine.
However, in certain conditions such as diabetes or when the renal threshold for glucose reabsorption is exceeded, the capacity of these transporters is overwhelmed, leading to the appearance of glucose in urine, a condition known as glucosuria.