pressure gradient

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pressure gradient

The difference in hydrostatic pressure on either side of a membrane. As the difference in pressures rises, filtration increases from the area of high pressure to the area of low pressure.
See also: gradient

pressure

stress or strain, by compression, expansion, pull, thrust or shear.

arterial pressure
the blood pressure in the arteries.
atmospheric pressure
the pressure exerted by the atmosphere, about 15 lb per square inch (2.17 kPa) at sea level.
capillary pressure
the blood pressure in the capillaries.
central venous pressure (CVP)
see central venous pressure.
cerebrospinal pressure
the pressure of the cerebrospinal fluid, normally 100 to 150 mmHg.
diastolic pressure
the lowest pressure recorded in the arterial blood pressure cycle. Represents the minimal pressure in the left ventricle which can maintain its ejection phase. See also blood pressure.
pressure gauge
a device attached to the outlet of gas tanks to measure internal pressure which indicates the quantity of gas remaining.
pressure gradient
the rate of increase (or decrease) in the magnitude of the pressure being measured.
intracranial pressure (ICP)
see intracranial pressure.
intraocular pressure (IOP)
the pressure exerted against the outer coats by the contents of the eyeball.
pressure load
mean circulatory filling pressure
a measure of the average (arterial and venous) pressure necessary to cause filling of the circulation with blood; it varies with blood volume and is directly proportional to the rate of venous return and thus to cardiac output.
pressure natriuresis
thought to participate in regulating the volume of extracellular fluid levels when the normal neurohumoral mediators are impaired; the increase in water and sodium ion excretions which occur when blood pressure is elevated because of an increase in the circulating blood volume.
pressure necrosis
necrosis of tissue caused by exclusion of circulation by external compression, e.g. in prolonged recumbency, or due to too-tight bandage, collar, harness.
negative pressure
pressure less than that of the atmosphere.
oncotic pressure
the osmotic pressure of a colloid in solution.
osmotic pressure
the potential pressure of a solution directly related to its solute osmolar concentration; it is the maximum pressure developed by osmosis in a solution separated from another by a semipermeable membrane, i.e. the pressure that will just prevent osmosis between two such solutions.
pressure point granuloma
see pressure points (below).
pressure point pyoderma
see pressure points (below).
pressure points
parts of the body subject to pressure when the animal is recumbent, wearing harness or saddlery, or during restraint. Usually bony prominences such as the point of the hock, hip, shoulder, elbow and lateral aspects of limbs. These are predisposed to callus formation, infection pyoderma and granulomas.
positive pressure
pressure greater than that of the atmosphere.
pulse pressure
difference between systolic and diastolic pressures in arteries.
pressure receptors
e.g. the blood pressure receptors in the aortic arch and the carotid sinus.
pressure sore
decubitus ulcer.
systolic pressure
the highest reading in the arterial blood pressure cycle. A reflection of the ejection pressure of left ventricular systole, and the elasticity of the arterial system.
venous pressure
the blood pressure in the veins. See also central venous pressure.
wedge pressure
intravascular pressure as measured by a swan-ganz catheter introduced into the pulmonary artery; it permits indirect measurement of the mean left atrial pressure.
pressure wrap
bandages which apply pressure to underlying tissues; used after trauma to limit the development of edema, and in the management of lymphedema.
References in periodicals archive ?
Far downstream from the U-bend, it can be noticed that the pressure gradients at 141d and 59d are very close, especially at low and medium vapor qualities.
Due to this heterogeneity, the surface responds in a different manner to the solar cycle, yielding a differential heating (and cooling) of the ground, which produces horizontal pressure gradient based circulations (Dai and Wang, 1999).
A pressure gradient develops and accumulation of the gas continues under a constant pressure gradient within the system.
A hepatic venous pressure gradient of more than 20 mm Hg 24 hours after a variceal hemorrhage predicts higher rates of bleeding and 1-year mortality.
We've had some pretty strong pressure gradients here,'' said National Weather Service weather specialist Bill Hoffer.
Four pressure recording data loggers were set up to measure maximum air pressure and determine the difference in pressure gradients throughout the system.
Pressure gradients were run in the well, confirming that the gas zones are over-pressured, consistent with the higher than normal pressures encountered in the same sands in offsetting wells in the McCully field.
Follow-up was continued for two other patients because their peak pressure gradients were found to be 22 mmHg and 27 mmHg, respectively, with no obvious symptoms.
Measurements can be performed in the danger zone hydrogen sulphide and abnormally high reservoir pressure gradients and directional and horizontal holes.
The volume includes equations for problems such as mud weight, hydrostatic pressure, pressure gradients, annular velocity, control drilling, and circulating hydraulic horsepower.
These pressure gradients are encountered in many industrial applications like the flow over airfoils or hydrofoils, turbine blades, helicopter rotors, in diverging channels like diffusers, over aft hulls of ships and airships, submarines, etc.
Two-phase pressure gradients across a test section are measured for inlet quality of 0.