Learning Objective:
Understand and calculate Filtration Fraction (FF) — the proportion of plasma that is filtered through the glomerulus.

Formula:

Explanation:

• = Filtration Fraction
• = Glomerular Filtration Rate
• = Renal Plasma Flow

It represents the fraction of renal plasma flow that becomes glomerular filtrate.

Concept Summary:

• Normal FF ≈ 20% (i.e., ~20% of plasma entering glomeruli is filtered).
• Changes in afferent/efferent arteriolar tone can alter FF:
  • ↑ Efferent constriction → ↑ GFR → ↑ FF
  • ↑ Afferent constriction → ↓ GFR → ↓ FF

Example:

Given:

✅ Answer: Filtration Fraction = 20%