filtration

filtration /fil·tra·tion/ (fil-tra´shun) passage through a filter or other material that prevents passage of certain molecules, particles, or substances.

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fil·tra·tion (fl-trshn)

n.

The process of passing a liquid through a filter.

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filtration

[filtrā′shən]

Etymology: Fr, filtrer, to strain

the addition of sheets of metal to a beam of x-rays for the purpose of altering the energy spectrum and thus the imaging characteristics and penetrating ability of the radiation. Filtration is generally accomplished with aluminum or copper at low to medium energy and with tin, copper, or aluminum at higher energy.

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filtration

(filtrā´shn),
n the use of absorbers for the selective attenuation of radiation of certain wavelengths from a useful primary beam of x-radiation.

filtration, built-in,

n the filtration put into effect by nonremovable absorbers deliberately built into the tube-head assembly to increase the inherent beam filtration.

filtration, external,

n the action of absorbers external to the tube-head assembly, consisting of added filtration plus the attenuating effect of materials of which any closed-end cone such as a pointer cone may be made. See also filter, added.

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filtration

passage through a filter or through a material that prevents passage of certain molecules, e.g. capillary wall, blood-brain barrier, radiographic grid.

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filtration angle

developmental or acquired distortion of this part of the eye is the common cause of glaucoma. It is the space bounded by the sclera externally, the ciliary muscle posteriorly, the root of the iris medially and the anterior chamber of the eye anteriorly. Within the space is the filtering mechanism, a mass of anastomosing mesodermal spindle cells with many perforations between them.

filtration barrier

the physiological function which limits the passage of small molecules through the renal corpuscle.

glomerular filtration

the process by which glomerular filtrate is formed, involving the balance of pressures across the walls of the glomerular capillaries.

inherent filtration

attenuation of the primary x-ray beam as a result of its passage out of the x-ray tube through the insulating medium and tube window.

filtration membrane

the membrane which stretches across the filtration slits in the renal corpuscle.

filtration pressure

the net driving force which pushes fluid into tissue spaces and out of vascular sites; the net result between capillary osmotic pressure and intravascular hydrostatic pressure.

filtration slits

openings in the glomerular corpuscle which are part of the filtration process in the renal glomerulus.