Which of the following substances is not normally found in the glomerular filtrate?

• A. Glucose
• B. Urea
• C. Proteins
• D. Sodium ions

Answer: (C)

Verified step by step guidance

1. Understand the process of glomerular filtration: The glomerulus is a network of capillaries in the kidney where blood is filtered. The filtration process allows water and small molecules to pass through while retaining larger molecules and cells.
2. Identify the components of normal glomerular filtrate: Typically, the filtrate includes water, glucose, ions (such as sodium), and waste products like urea. These are small enough to pass through the filtration barrier.
3. Consider the size and charge of molecules: Proteins are generally large molecules. The filtration barrier in the glomerulus is designed to prevent large molecules, such as proteins, from passing into the filtrate.
4. Recognize the role of the filtration barrier: The barrier consists of endothelial cells, a basement membrane, and podocytes. These structures work together to prevent large molecules and cells from entering the filtrate.
5. Conclude which substance is not normally found in the filtrate: Given the size exclusion properties of the glomerular filtration barrier, proteins are not typically found in the glomerular filtrate under normal conditions.