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The filtration fraction is the amount of plasma that is actually filtered through the kidney. This can be defined using the equation: FF= GFR / RPF FF is the filtration fraction; GFR is the glomerular filtration rate; RPF is the renal plasma flow; Normal human FF is 20%.
The glomerular filtration rate (GFR) describes the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. [3] Creatinine clearance (C Cr ) is the volume of blood plasma that is cleared of creatinine per unit time and is a useful measure for approximating the GFR.
In renal physiology, the filtration fraction is the ratio of the glomerular filtration rate (GFR) over the renal plasma flow (RPF). Filtration Fraction, FF = GFR/RPF, or =. The filtration fraction, therefore, represents the proportion of the fluid reaching the kidneys that passes into the renal tubules. It is normally about 20%.
This is the numerator in the equation. The denominator is the total amount of sodium filtered by the kidneys. This is calculated by multiplying the plasma sodium concentration by the glomerular filtration rate (GFR) calculated using creatinine filtration. The flow rates then cancel out, simplifying to the standard equation: [1]
In physiology, filtration coefficient (Kf) is the product of a biological membrane's permeability to water and the surface area of the membrane. Typical units of Kf are mL/min/mmHg. The rate of filtration across the membrane is, by definition, the product of Kf and the net filtration pressure across the membrane.
This is performed at the microscopic level by many hundreds of thousands of filtration units called renal corpuscles, each of which is composed of a glomerulus and a Bowman's capsule. A global assessment of renal function is often ascertained by estimating the rate of filtration, called the glomerular filtration rate (GFR).
Renal professionals consider the glomerular filtration rate (GFR) to be the best overall index of kidney function. [33] The National Kidney Foundation offers an easy to use on-line GFR calculator [34] for anyone who is interested in knowing their glomerular filtration rate. (A serum creatinine level, a simple blood test, is needed to use the ...
Clearance of a substance is sometimes expressed as the inverse of the time constant that describes its removal rate from the body divided by its volume of distribution (or total body water). In steady-state, it is defined as the mass generation rate of a substance (which equals the mass removal rate) divided by its concentration in the blood.