GFR is determined by –
**Core Concept**
Glomerular filtration rate (GFR) is a critical measure of renal function, reflecting the kidneys' ability to filter waste products from the blood. It is influenced by factors that affect the glomerular filtration barrier, including the glomerular hydrostatic pressure, glomerular capillary oncotic pressure, and the surface area of the glomeruli.
**Why the Correct Answer is Right**
The correct answer is determined by the equation of GFR, which is given by the formula: GFR = (Kf x S x ΔP) / (1 - σ x ΔP), where Kf is the glomerular filtration coefficient, S is the surface area of the glomeruli, ΔP is the net filtration pressure, and σ is the reflection coefficient of the glomerular basement membrane. This equation highlights the importance of glomerular hydrostatic pressure, glomerular capillary oncotic pressure, and the surface area of the glomeruli in determining GFR.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not take into account the surface area of the glomeruli, which is a critical determinant of GFR.
**Option B:** This option is incorrect because it does not consider the glomerular capillary oncotic pressure, which opposes the filtration of fluid from the glomeruli.
**Option C:** This option is incorrect because it does not account for the reflection coefficient of the glomerular basement membrane, which affects the amount of fluid that is filtered from the glomeruli.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that GFR is a measure of renal function that is affected by factors such as age, sex, and body size. In clinical practice, GFR is often estimated using the Modification of Diet in Renal Disease (MDRD) equation or the Cockcroft-Gault equation.
**Correct Answer: D. The equation of GFR, which is given by the formula: GFR = (Kf x S x ΔP) / (1 - σ x ΔP)**