The presence of a concentration
gradient for urea is crucial for successful blood purification using an artificial
kidney, or dialysis. To which of the following does that
also apply? (A) Glucose, (B) amino acids, (C)
glycogen, or (D) none of the answers are correct.
This question is asking us about
the process of dialysis. Dialysis is used when a patient has
kidney failure. This means that their kidneys have
stopped functioning properly. The kidneys are a pair of organs
that are primarily responsible for filtering wastes from the blood. Dialysis replaces the function of
the kidneys by removing wastes from the blood. The blood is pumped out of the
patient and through a network of semipermeable tubing. Semipermeable means that some
molecules can pass through and others cannot.
You may recall that molecules move
down their concentration gradient from areas of high concentration to areas of low
concentration. There is no waste in the dialysis
fluid, and there is some waste in the blood. So, the waste moves from the blood
and into the dialysis fluid. The dialysis fluid carries it
away. This is how the process of dialysis
removes waste from the bloodstream.
Urea is a type of metabolic waste
generated by the metabolism of proteins. It is one of the waste materials
removed from the blood by kidney dialysis. The correct answer choice would be
another type of waste that needs to be removed from the bloodstream.
Let’s look at our choices. Glucose is a molecule that is used
to generate cellular energy. It is not a waste product. Amino acids are the building blocks
of proteins. They are not a waste product. Glycogen is a macromolecule used
for the storage of glucose, which our cells need. It is not a waste product. That means that the correct
response is “None of the answers are correct.”