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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.
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%.
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).
Para-aminohippurate (PAH) clearance is a method used in renal physiology to measure renal plasma flow, which is a measure of renal function. [citation needed]PAH is completely removed from blood that passes through the kidneys (PAH undergoes both glomerular filtration and tubular secretion), and therefore the rate at which the kidneys can clear PAH from the blood reflects total renal plasma flow.
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%.
Effective renal plasma flow (eRPF) is a measure used in renal physiology [1] to calculate renal plasma flow (RPF) and hence estimate renal function.. Because the extraction ratio of PAH is high, it has become commonplace to estimate the RPF by dividing the amount of PAH in the urine by the plasma PAH level, ignoring the level in renal venous blood.
The "Hepatic Extraction Ratio" is a similar measurement for clearance of a substance (usually a pharmacological drug) by the liver. It is defined as the fraction of drug removed from blood by the liver, and depends on 3 factors— the hepatic blood flow, the uptake into the hepatocytes, and the enzyme metabolic capacity.
The threshold at which the loop of Henle flow rate initiates feedback responses is affected. A high protein diet affects the feedback activity by making the single nephron glomerular filtration rate higher, and the Na and Cl concentrations in early distal tubule fluid lower. The signal eliciting the TG feedback response is affected.