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Board Review CRNA (Sweat Book) > Physics and Chemistry > Flashcards

Physics and Chemistry Flashcards

1
Q

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

A

boils

*this is why desflurane is placed in a heated vaporizer

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2
Q

Vapor pressure is a function of _______.

A

temperature

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3
Q

The % concentration of any gas is found by _______.

A

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

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4
Q

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

A

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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5
Q

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

A

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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6
Q

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

A

39 degrees C; approximately 2 atm or 1500mmHg

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7
Q

Name some units of pressure.

A

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

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8
Q

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

A

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

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9
Q

What type of gauges measure high pressures?

A

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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10
Q

Define tension.

A

“force” along a straight line

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11
Q

T= P x r is what law?

A

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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12
Q

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?

A

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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13
Q

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

A

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

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14
Q

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

A

the radius

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15
Q

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

A

viscosity

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16
Q

When does flow become turbulent?

A

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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17
Q

Resistance to flow ______ when flow becomes turbulent.

A

increases

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18
Q

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

A

Joule-Thompson effect

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19
Q

How to remember the common gas laws???

A

Can the gay people possible b—- v—–.

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20
Q

What is the generalized ideal (universal) gas law?

A

PV=nRT

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

21
Q

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

A

mole

22
Q

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

A

Avogadro

23
Q

What is Avogadro’s number?

A

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

24
Q

What was Avogadro’s hypothesis?

A

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

25
Q

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

A

22.4 x 2= 44.8 liters

26
Q

What is critical temperature?

A

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

27
Q

Adiabatic means______.

A

heat cannot be dissipated (“constant heat”)

28
Q

What is the Joule-Thompson effect?

A

“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)

29
Q

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

A

1900-2200psi; 660L

30
Q

What law is all about diffusion?

A

Ficks

31
Q

Diffusion rate of a gas is directly proportional to:______

A

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

32
Q

Diffusion rate of a gas is inversely proportional to:______

A

1) membrane thickness

2) the square root of the molecular weight

33
Q

Fick’s law explains what 4 clinical scenarios?

A

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

34
Q

What does Graham’s law explain?

A

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

35
Q

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

A

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

36
Q

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

A

the same everywhere

37
Q

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

A

simple diffusion across the placental barrier

38
Q

Diffusion of gas from alveoli to blood requires:______.

A

a difference in partial pressure

39
Q

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

A

1) lipid INSOLUBLE (ionized, etc)

2) large (high molecular weights)

40
Q

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

A

a semipermeable membrane

41
Q

What does osmosis require?

A

1) semipermeable membrane

2) difference in concentration of solutes

42
Q

________ that accompanies liver disease is the cause of ascites.

A

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

43
Q

Who’s law explains the pulse-ox?

A

Beer-Lambert

44
Q

How is the majority of heat lost?

A

radiation 60%

45
Q

List the routes of heat loss from greatest to least.

A

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

46
Q

What happens to relative humidity as temperature falls?

A

relative humidity increases as temperature falls because saturated vapor pressure falls

relative humidity (%)= actual vapor pressure
________________ x 100%
saturated vapor pressure

47
Q

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

A

47mmHg

48
Q

What happens to the air when temperature falls?

A

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

49
Q

REVIEW PAGES 316-317 for all of the LAWS

A

REVIEW PAGES 316-317 for all of the LAWS

Board Review CRNA (Sweat Book) (38 decks)

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