Filtration fraction

Filtration fraction

In renal physiology, the filtration fraction is the ratio of the glomerular filtration rate (GFR) to the renal plasma flow (RPF). RPF = 1-hematocrit(renal blood flow)

Filtration Fraction = GFR/(1-hematocrit)RBF

The filtration fraction therefore represents the proportion of the fluid reaching the kidneys which passes into the renal tubules.

The GFR on its own is the most common and important measure of renal function. However, in a condition such as renal stenosis, the blood flow to the kidneys is reduced. The filtration must therefore be increased in order to perform the normal tasks of the kidney in balancing fluid and electrolytes in the body. This would be reflected by a high filtration fraction, showing that the kidneys have to do more work with the fluid they are receiving.

Catecholamines (Norepinephrine and Epinephrine) increase the filtration fraction by vasoconstriction of Afferent and Efferent Arterioles which poss alpha 1 adrenergic receptors.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • filtration fraction — the portion of the plasma that is filtered through the renal glomerular capillary membrane, calculated as the fraction of total glomerular filtration rate divided by total renal blood flow …   Medical dictionary

  • fraction — 1. The quotient of two quantities. 2. An aliquot portion or any portion. 3. As a verb, to separate into portions. amorphous f. of adrenal cortex noncrystalline residue of an acetone extract of the ad …   Medical dictionary

  • Renal function — Diagram showing the basic physiologic mechanisms of the kidney Renal function, in nephrology, is an indication of the state of the kidney and its role in renal physiology. Glomerular filtration rate (GFR) describes the flow rate of filtered fluid …   Wikipedia

  • Renal physiology — This illustration demonstrates the normal kidney physiology. It also includes illustrations showing where some types of diuretics act, and what they do. Renal physiology (Latin rēnēs, kidney ) is the study of the physiology of the kidney. This… …   Wikipedia

  • renal system — ▪ anatomy Introduction  in humans (human body), organ system that includes the kidneys, where urine is produced, and the ureters, bladder, and urethra for the passage, storage, and voiding of urine.       In many respects the human excretory, or… …   Universalium

  • Clearance (medicine) — In medicine, the clearance is a measurement of the renal excretion ability. Although clearance may also involve other organs than the kidney, it is almost synonymous with renal clearance or renal plasma clearance. Each substance has a specific… …   Wikipedia

  • PAH clearance — Parameter Value renal blood flow RBF=1000 ml/min hematocrit HCT=40% renal plasma flow RPF=600 ml/min filtration fraction FF=20% glomerular filtration rate GFR=120 ml/min …   Wikipedia

  • FF — Abbreviation for filtration fraction. * * * degree of fineness of abrasive particles; fat free; father factor; fecal frequency; fertility factor; field of Forel; filtration fraction; fine fiber; fine focus; finger flexion; finger to finger;… …   Medical dictionary

  • Aminohippuric acid — Aminohippurate Systematic (IUPAC) name 2 [(4 Aminobenzoyl)amino]acetic acid Clinical data Pregnancy cat.  ? …   Wikipedia

  • Vasopressin — Arginine vasopressin Space filling model of arginine vasopressin …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”