Question

Which of the following is not filtered out of the blood by the glomerulus:red blood cells, electrolytes, water, or glucose?

Answer 1

Red Blood Cells, due to their large size.

Explanation:

The glomerulus is a meshy network of capillaries at the start of the nephron in our kidneys. They are the first step in blood filtration, as substances can go through the capillary endothelial cells, basement membrane, and finally podocytes into Bowman's Capsule to be filtered outside the body.

This filtration process relays on size-dependent permeability. Meaning that small molecules can pass while large molecules can't.

Small molecules include: water, electrolytes, glucose and small proteins.
Large molecules include: cells and large proteins.

So large molecules like Red Blood Cells can't pass through.

I hope that answered your question.

Further Reading:

1. Permeability Table of Different Substances
2. Glomeruslus Structure
3. Bowman's Capsule