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Nu624 chem phys

Pascal Laplace flow pressure force tension

QuestionAnswer
Pressure equals Force exerted by atoms and molecules
Pressure is generated by Ke
Speed direction and movement of atoms and molecules Not constant and varies
Pressure equation Pressure = force/area
English unit of pressure Pound
Pound is not a unit of Mass
English unit of force Lbs per sq feet or lbs per sq inch
Si means System international
Si unit of pressure Newton per sq meter
Newton per sq meter is aka Pascal or kilo pascal kPa
One atmosphere equal 101.3 Kpa or 14.69 lbs per sq inch
Desflurane is under how much pressure? 2atm or 1500mmhg ( why mmHg?)
Cylinder pressure Sum of all molecular forces in a close container
Pressure in cylinder is measured in Psig
Empty cylinder pressure inside is what 750 psig same as atmospheric pressure
Full tank of n20 745psig
Full tank of O2 1900 to 2200 psig
Gauge that measure pipeline or cylinder Bourdon gauge
Bourdon gauge has no fluid so it's a Aneroid
Mechanism of bourdon gauge Hollow metal bent into curve sealed and linked to clock like mechanism As pressure increases tube straightens out causing into read higher pressure
Who regulated bourdon gauge ASTM aka American society for testing and measuring
What are the regulation set forth by the ASTM Must have a 38 mm diameter, loweest pressure between 6 and 9 o'clock and name and color of gas been gauge
Other units of pressure which isn't gas MmHg or torr or cmH2o
Mmgh or torr used for Tourniquet or BP cuff
On anesthesia machine high pressure or continuos pressure is measured in what? Cm of water
Three physics principles in liquids 1. Proportional pressure and height. High then high pressure and vice versa 2. Pressure in liquid increases with depth below surface 3. At given depth pressure is equal in all directions
Turp can cause what Dilutional hypo natremia
Etiology of dilutional hypo natremia due to Turp Absorption of irrigating fluid by open venous channels Due to the height of irrigating fluid. Higher the bag higher the absorption .
Pressure reliefe valve anesthesia machine is located where? Near common gas outlet,
Pressure relieve valve opens To atmosphere and releases fresh gas when preset gas is exceeded
Reliefe valve limit the machine to do what? Deliver jet ventilation
Inspiratory andexpiratory valves are what? Unidirectional
Unidirectional valves contain what Disks that rise and fall.
Incompetence of unidirectional is not Uncommon! System can be cleaned.
Pressure reducing valves aka Pressure regulators
Mechanism of pressure regulators Balance the force of spring against force from compressed gas
Where does surface tension occur At air/liquid interface
Surface tension is what The attractive forces between molecules at surface of liquid
Surface tension creates what? Barrier between air and liquid, fast prevents liquid evaporation, allows certain insects to walk on water
Measurement of surface tension Dynes per cm at 20 deg C
Dynes is a unit of what? Force
Thin film of liquid in lungs tends to do what Create surface tension and collapse the lung
What prevents collapse of lung Surfactant
Surfactant is secreted by? Type 2 alveolar epithelial cells
Surfactant works how? Decrease surface tension, decrease cohesive forces
3 physiological benefits of surfactant? 1.increase overall lung compliance 2. Reduce tendency of small alveolar to dump into larger 3. Reduce fluid leak from pulmonary capillaries (pulmonary edema)
Si unit of pressure? Pascal or newton per sq meter or Kpa
Pascals principle states? Pressure applied to a completely enclosed fluid ( water balloon) that pressure is transmitted undiminished to all parts of the fluid and the enclosing wall
Pascals pressure principles has to do with what? Aneurism
Pressure exerted by force of heart contraction is distributed Undiminished throughout vascular system
Pressure at a weak point of a vessel Has higher pressure acting upon it, may cause rupture and dissect
Law of Laplace has to do with what? Pressure, surface tension, radius
Laplace law and alveoli Magnitude of inward pressure is equal to twice the surface tension divided by the radius
Laplace equation P = 2T/R P is dynes/cm pressure T is surface tension dynes/cm R is radius
Laplace implies what in respect to alveoli Larger surface tension involves a larger force pushing inward into alveoli
Relationship of radius and force Small radius = large force so it's inversely related
Smaller alveoli with higher pressure does not collapse and fill larger alveoli why? Surfactant
Surfactant acts on both small and large alveoli BUT Has greater effect on smaller alveoli
Outcome of surfactant? Surfactant reduces increased wall tension
During ohs what diverts the blood to cardio-bypass? Aortic cross clamp
Mechanical response of left vent aortic cross claming is determined how? Largely by intrinsic length tension velocity of myocardium
Tension equals? Pressure x radius ( think after load)
After load is determined by? Ventricular radius and systolic intra ventricular pressure
Cross clamping occurs during what? OHS, abdominal aortic aneurysmectomy and infrarenal aortic cross clamping
Tube is? Longer length than diameter
Orifice is? Larger diameter than length
Rate of fluid flow through a tube is based on what 5 things? 1. Radius or cross section 2. Pressure gradient difference between p1 and p2 3. Length of tube 4. Viscosity 5. Density of fluid
Flow equation of gas or liquid Flow = quantity of liquid / time F = Q / time Quantity of material per unit of time is flow.
Flow rate is proportional to what? Pressure
Flow in respect to diameter ? Halfing the diameter reduces flow to one sixteenth 1/16 of original
Length of tube in respect to flow? Cut length in 1/2 and you DOUBLE the flow
Most profound impact on flow comes from? Diameter
Meniscus shapes? Convex or concave
Convexity or concoveity based on what? Molecular interaction of liquid and glass.
Convex meniscus Hg for example to interaction with glass does not wet glass
Concave meniscus Surface tension of Liquid like water interact with glass and sides are pulled up, " wets" the glass.
Created by: Rooz