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Nu624 chem phys
Pascal Laplace flow pressure force tension
Question | Answer |
---|---|
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. |