EasyBiologyHigh School (9–10)GeneralLife Processes › ExcretionHuman Body › Excretory SystemConceptual
Glucose passes from the glomerulus into Bowman's capsule, together with the water.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Glucose passes from the glomerulus into Bowman's capsule, together with the water. Yet the urine of a healthy person has no glucose. Where does the glucose go? Why may glucose appear in the urine of a person whose blood sugar stays very high?
Need a reminder? The key ideaShow
In each nephron, the glomerulus inside Bowman's capsule filters water, glucose, amino acids, salts and urea out of the blood. The tubule takes back glucose, amino acids, salts and much of the water. What is left is urine. An artificial kidney removes wastes by dialysis, but takes nothing back.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Where it goes. As the filtrate flows along the tubule, all the glucose is reabsorbed into the capillaries around it. None is left for the urine.
Step 2. Too much sugar. If the blood holds far too much glucose, the filtrate holds too much as well. The tubule cannot take all of it back, so some stays in the urine.
Answer: In a healthy person, all the filtered glucose is taken back into the blood in the tubule. With very high blood sugar there is more than the tubule can take back, so some glucose passes into the urine.
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