Which of the following substances would pass through the filtration membrane to become part of the filtrate under normal circumstances? (Circle all that apply.)

a. Sodium ions

b. Albumin

c. Glucose

d. Erythrocytes

e. Leukocytes

f. Amino acids

g. Urea

Video transcript

Hi everybody. Our next question says which of the following substances cannot pass through the filtration membrane during the glom, glomerular filtration process. A proteins, B water CN A plus or sodium ion D creatinine or E bicarbonate. Well, you can get to this answer. If looking at these, you can recall which of these makes the largest molecule because it makes sense that the largest molecule would be the least one able to pass through a filtration membrane. And that is choice a proteins. And that is indeed our answer. Uh think of the openings in the filtration membrane as a series of if you ever uh played with like little sieves as a child, like to sift sand or things and imagine a series of them stacked together with different size openings. But proteins are just too large to pass through any of them. And in fact, under normal circumstances, uh protein is filtered out right at the beginning. It should not ever appear in urine. If it does, it's always an indication that something's gone wrong with that filtration process. So choice B water can of course freely go through until you get to the non water permeable portion of the collecting duct or excuse me of the convoluted tubule. Choice CN A plus those ions very small can pass through. Creatinine is a waste product that also is small enough to pass through the fil into the filtrate. And choice E bicarbonate is another ion that can also pass through. So some of these things water and ions will then get reabsorbed but initially will pass through and the filtrate. The one that just cannot pass through at all in the glomerular filtration process is choice a proteins. See you in the next video.