partial pressure

pressure /pres·sure/ (P ) (presh´er) force per unit area.

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arterial pressure  blood p. (2).

blood pressure 

1. the pressure of blood against the walls of any blood vessel.

2. the pressure of blood on the walls of the arteries, dependent on the energy of the heart action, elasticity of the arterial walls, and volume and viscosity of the blood; the maximum or systolic pressure occurs near the end of the stroke output of the left ventricle, and the minimum or diastolic late in ventricular diastole.

central venous pressure  (CVP) the venous pressure as measured at the right atrium, done by means of a catheter introduced through the median cubital vein to the superior vena cava.

cerebrospinal pressure  the pressure or tension of the cerebrospinal fluid, normally 100–150 mm. as measured by the manometer.

detrusor pressure  the pressure exerted inwards by the detrusor urinae muscles of the bladder wall.

diastolic pressure , diastolic blood pressure see blood p.

end-diastolic pressure  the pressure in the ventricles at the end of diastole, usually measured in the left ventricle as an approximation of the end-diastolic volume, or preload.

intracranial pressure  (ICP) pressure of the subarachnoidal fluid.

intraocular pressure  the pressure exerted against the outer coats by the contents of the eyeball.

intravesical pressure  the pressure exerted on the contents of the urinary bladder; the sum of the intra-abdominal pressure from outside the bladder and the detrusor pressure.

maximum expiratory pressure  (MEP) a measure of the strength of respiratory muscles, obtained by having the patient exhale as strongly as possible against a mouthpiece; the maximum value is near total lung capacity.

maximum inspiratory pressure  (MIP) a measure of the strength of respiratory muscles, obtained by having the patient inhale as strongly as possible with the mouth against a mouthpiece; the maximum value is near the residual volume.

mean arterial pressure  (MAP) the average pressure within an artery over a complete cycle of one heartbeat.

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.

negative pressure  pressure less than that of the atmosphere.

oncotic pressure  the osmotic pressure due to the presence of colloids in solution.

osmotic pressure  the pressure required to prevent osmosis through a semipermeable membrane between a solution and pure solvent; it is proportional to the osmolality of the solution. Symbol π.

partial pressure  the pressure exerted by each of the constituents of a mixture of gases.

positive pressure  pressure greater than that of the atmosphere.

positive end-expiratory pressure  (PEEP) a method of mechanical ventilation in which pressure is maintained to increase the volume of gas left in the lungs at the end of exhalation, reducing shunting of blood through the lungs and improving gas exchange.

pulmonary artery wedge pressure  (PAWP), pulmonary capillary wedge pressure (PCWP) intravascular pressure as measured by a catheter wedged into the distal pulmonary artery ; used to measure indirectly the mean left atrial pressure.

pulse pressure  the difference between systolic and diastolic pressures.

systolic pressure , systolic blood pressure see blood p.

Valsalva leak point pressure  the amount of pressure on the bladder by a Valsalva maneuver at which leakage of urine occurs; a measure of strength of the urethral sphincters.

venous pressure  the pressure of blood in the veins.

wedge pressure  blood pressure measured by a small catheter wedged into a vessel, occluding it, e.g., pulmonary capillary wedge p.

wedged hepatic vein pressure  the venous pressure measured with a catheter wedged into the hepatic vein; used to locate the site of obstruction in portal hypertension.

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partial pressure

n.

The pressure that one component of a mixture of gases would exert if it were alone in a container.

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Partial pressure

The pressure exerted by one of the gases in a mixture of gases. The partial pressure of the gas is proportional to its concentration in the mixture. The total pressure of the gas mixture is the sum of the partial pressures of the gases in it (Dalton's Law) and as the total pressure increases, each partial pressure increases proportionally.

Mentioned in: Nitrogen Narcosis

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partial pressure,

the pressure exerted by any one gas in a mixture of gases or in a liquid, with the pressure directly related to the concentration of that gas to the total pressure of the mixture. The concentration of oxygen in the atmosphere represents approximately 21% of the total atmospheric pressure, calculated at 760 mm Hg under standard conditions. Therefore, the partial pressure of atmospheric oxygen is about 160 mm Hg (760 mm Hg × 0.21).

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pressure,

n a stress or strain that may occur by compression, pull, or thrust; an applied force.

pressure area,

n See area, pressure.

pressure atrophy,

n See atrophy, pressure.

pressure, biting,

n the actual or potential power used in bringing the teeth into contact. See also pressure, occlusal.

pressure, blood,

n See blood pressure.

pressure, deeper,

n a pressure to the body–in excess of that which stimulates Meissner's corpuscles, Merkel's disks, or the hair receptors of light touch–that stimulates the deeper receptors such as Pacini's corpuscles. These latter deep-pressure perception organs lie in the inner layers of the dermis and in the muscle and tendon groups.

pressure, equalization of,

n the act of distributing pressure evenly.

pressure, hand,

n force applied by an instrument held in the hand.

pressure, hydraulic,

n pressure transmitted by a liquid trapped between the tooth and a restoration being cemented.

pressure, hydrostatic,

n the pressure in the circulatory system exerted by the volume of blood when it is confined in a blood vessel. The hydrostatic pressure, coupled with the osmotic pressure within a capillary is opposed by the hydrostatic and osmotic pressure of the surrounding tissues. Fluids flow from the higher pressure areas to the lower pressure areas.

pressure, intrapleural,

n pressure within the pleura.

pressure, occlusal,

n any force exerted on the occlusal surfaces of teeth. See also force, occlusal and load, occlusal.

pressure, osmotic,

n the stress that develops when solutions containing different concentrations of solute in a common solvent are separated by a membrane that is permeable to the solvent but not the solute.

pressure, partial,

n the pressure exerted by each of the constituents of a mixture of gases.

pressure, pulse,

n the difference between systolic and diastolic pressure.

pressure sensibility,

n the ability to detect light touch and deep pressure. See also corpuscle, Meissner's; corpuscle, Merkel's; and corpuscle, Pacini's.

pressure sore,

n a decubitus ulcer caused when the bony protuberances of the body are subjected to chronic pressure from the weight of the body without breaks.

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partial

pertaining to or having the characteristics of a part of something.

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partial budget

see partial budget.

partial pressure

the pressure exerted by a specific gas in a mixture of gases. Because the amount of the gas dissolved in a liquid is proportional to the pressure of the gas on the fluid the concentration of a gas in a fluid is expressed as its partial pressure.

partial thromboplastin time (PTT)

see activated partial thromboplastin time.