Albumin is the large protein molecule found in egg white and blood plasma. Table salt dissociates into sodium and chloride ions. Urea is assembled in the liver. In a healthy person, what is the fate of the majority of these molecules as they pass through a nephron?
A) All three remain in the bloodstream.
B) All three pass across to the glomerular capsule and are excreted in urine.
C) All three pass across to the glomerular capsule, but the salt ions are mostly reabsorbed.
D) Albumin remains in the blood; salt ions and urea are passed across and excreted.
E) Albumin remains in the blood, salt ions pass across but are reabsorbed, and the urea is passed across and excreted.

Question

Quizplus · Accepted Answer

Albumin remains in the blood because it is too large to pass through the filtration barrier of the glomerulus. Salt ions (sodium and chloride) do pass through the filtration barrier, but they are mostly reabsorbed in the proximal tubule and loop of Henle, and only a small portion is excreted in the urine. Urea, on the other hand, is freely filtered and is mostly excreted in the urine, but a small amount may also be reabsorbed depending on the body's needs. Therefore, the majority of these molecules will have albumin remaining in the blood, salt ions being reabsorbed or excreted in small amounts, and urea being excreted in the urine.

Albumin Is the Large Protein Molecule Found in Egg White