Physics and Chemistry Flashcards by Brandon Taylor

The closer the vapor pressure is to atmospheric pressure, the more easily it _____.

boils

*this is why desflurane is placed in a heated vaporizer

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Vapor pressure is a function of _______.

temperature

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The % concentration of any gas is found by _______.

dividing the pressure of the gas over the total pressure. (760 for 1 atm)

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If halothane was added to an isoflurane vaporizer, what would happen to the delivered concentration? halothane added to sevo?

added to iso: it would be about the same because the VP of halothane is 244 and Iso is 240mmHg

added to sevo: the delivered concentration would be more than what was dialed because the VP of halothane is 244mmHg versus Sevo VP of 170mmHg

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To remember what happens to a volatile agent that was added to the wrong vaporizer, just remember:
HLH
LHL

HLH= if a HIGHER VP agent is placed in a LOWER VP vaporizer, the concentration will be HIGHER

LHL= if a LOWER VP agent is placed in a HIGHER VP vaporizer, the concentration will be LOWER

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Desflurane vaporizer is heated to _____. What is the vapor pressure at this temperature?

39 degrees C; approximately 2 atm or 1500mmHg

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Name some units of pressure.

mmHg, cm H2O, atm, psi, kPa, bar

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What is the conversions for the following:
mmHg–> cm H2O
atm–> mmHg–> psi–> kPa–> bar
psi–> mmHg

1 mmHg= 1.36 cmH2O
1 atm=760 mmHg=14.7 psi=101 kPa= 1 bar
1 psi= 54 mmHg

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What type of gauges measure high pressures?

Bourdon gauge
measures the pressure relative to atmospheric pressure, not the absolute pressure–> when it reads 0… the pressure inside is equal to the atmosphere

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Define tension.

“force” along a straight line

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T= P x r is what law?

Law of LaPlace
as a structure expands (ie: radius increases–>cylindrical– blood vessel), the tension (force) in the wall of the structure increases

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In regards to the Law of LaPlace…. If you have a small soap bubble on one end of a straw and a large one on the other end, what will happen?

The small one will collapse because it has a greater pressure

this is ONLY true when there is a liquid-air interface….. this happens in ARDS, when smaller alveoli collapse due to lower than normal surfactant and empty into alveoli with lower pressures–> causing atelectasis
- normal alveoli with normal surfactant–> tension would increase with the radius

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According to Poiseuille’s Law, doubling the radius increases flow _____ times.

16 times
tripling the radius= increases flow 81 times
halving the radius= decreases flow to 1/16th of original

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Changing what single factor, according to Poiseuille’s Law, has the most impact on flow?

the radius

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What property of a fluid determines flow, when flow is laminar?

viscosity

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When does flow become turbulent?

If:

1) velocity of flow is high
2) tube wall is rough (corrugated)
3) kinks, bends, narrowing, or branches (RAE tube)
4) fluid flows through an orifice
* does not become turbulent when flowing through an angled tube if the angle is <25 degrees
5) reynolds # exceeds 1500-2000

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Resistance to flow ______ when flow becomes turbulent.

increases

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What explains why the temperature of a cylinder of compressed gas decreases as the gas is released?

Joule-Thompson effect

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How to remember the common gas laws???

Can the gay people possible b—- v—–.

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What is the generalized ideal (universal) gas law?

PV=nRT

where P= pressure, V=volume, T=temperature, n=moles of gas, and R=universal gas constant

One ____ is the molecular weight of a substance in grams.

mole

_______ described the relationship between the amount of gas and volume of gas.

Avogadro

What is Avogadro’s number?

the number of molecules in one mole of a substance is 6.022 x 10 to the 23rd

What was Avogadro’s hypothesis?

one mole of gas at standard temperature (0C) and standard pressure (1atm) occupies a volume of 22.4 liters

2 moles of gaseous N2O occupy what volume under standard conditions?

22.4 x 2= 44.8 liters

What is critical temperature?

gases liquefy if sufficient pressure is applied and the temperature is below a critical value called the critical temperature ex) critical temperature of N2O is 36.5C, so it can be compressed and stored as a liquid at room temperature ex) critical temperature of O2 is -119C, O2 cannot be liquefied at room temperature no matter how much pressure is applied

Adiabatic means______.

heat cannot be dissipated ("constant heat")

What is the Joule-Thompson effect?

"Joule is Cool" when compressed gas is allowed to escape freely into space, the process is adiabatic and cooling occurs (explains why condensation forms after opening a valve)

At 20C, a full E-cylinder of O2 has a pressure of ~ _______psi and contains approximately ______L.

1900-2200psi; 660L

What law is all about diffusion?

Ficks

Diffusion rate of a gas is directly proportional to:______

1) partial pressure gradient 2) membrane area 3) solubility of gas in membrane

Diffusion rate of a gas is inversely proportional to:______

1) membrane thickness | 2) the square root of the molecular weight

Fick's law explains what 4 clinical scenarios?

1) concentration effect 2) second gas effect 3) diffusion hypoxia 4) why turning on N2O leads to an increase in volume (or pressure) in gas spaces in the patients body

What does Graham's law explain?

why smaller substances diffuse in greater quantities (so does Fick's law)

What crosses the alveolar and capillary membrane the fastest... CO2 or O2?

CO2 diffuses 20 times faster than O2 d\t its fluid solubility

Equilibration of an inhalational agent occurs in the body when the partial pressure of the gas is _______.

the same everywhere

The process by which the fetus receives O2 and drugs is ________.

simple diffusion across the placental barrier

Diffusion of gas from alveoli to blood requires:______.

a difference in partial pressure

Agents that poorly penetrate the BBB or placental barrier have what characteristics?

1) lipid INSOLUBLE (ionized, etc) | 2) large (high molecular weights)

A membrane that is impermeable to one or more solutes is said to be _________.

a semipermeable membrane

What does osmosis require?

1) semipermeable membrane | 2) difference in concentration of solutes

________ that accompanies liver disease is the cause of ascites.

hypoalbuminemia---> less osmotic pressure keeping the fluid in albumin is the major determinant of intravascular volume

Who's law explains the pulse-ox?

Beer-Lambert

How is the majority of heat lost?

radiation 60%

List the routes of heat loss from greatest to least.

1) radiation 60% 2) convection 15-30% 3) evaporation 20% 4) conduction <5%

What happens to relative humidity as temperature falls?

relative humidity increases as temperature falls because saturated vapor pressure falls relative humidity (%)= actual vapor pressure ________________ x 100% saturated vapor pressure

What is the partial pressure of saturated water vapor at 37C?

47mmHg

What happens to the air when temperature falls?

air has reduced capacity to hold water vapor, so water condenses

REVIEW PAGES 316-317 for all of the LAWS