Physics Flashcards
what is the type of weaker force that liquid molecules exert BETWEEN/ON each other
van der waals forces
what is the pressure exerted by a vapor when, at any one temperature, an equilibrium is reached at which the same number of molecules are vaporizing as are returning to liquid
saturated vapor pressure
only within a closed container**
The temperature at which vapor pressure becomes equal to atmospheric pressure and at which all liquid changes to gas phase
boiling point
The higher the boiling point, the greater the chance it will be ___?
liquid
it takes longer to reach a gas phase
how are saturated vapor pressure and boiling point related?
inversely
The lower the boiling point, the higher the vapor pressure.
as temperature rises, does vapor pressure increase or decrease
increase
(think, boiling point decreases the hotter it gets)
Is vapor pressure a function of volume, temperature or pressure?
temperature
what is the equation for force? newton’s second law?
Force= mass x acceleration (F=ma)
what is the force applied over a surface
pressure
what is the equation for pressure
Pressure=force/area
what is the pressure of 1 newton acting over 1 square meter – N/m2
pascal (Pa)
however, kPa is usually used
what is atmospheric pressure (ATM) in bar?
1 bar
what is atmospheric pressure (ATM) in kPa?
100
what is atmospheric pressure (ATM) in mmHg?
760
what is atmospheric pressure (ATM) in cmH2O?
1034
what is atmospheric pressure (ATM) in psi?
14.7
what is 1kPa in mmHg?
7.5*****
what is 1kPa in cmH2O?
10.34
what is 1kPa in psi
0.147
what is gauge pressure + atmospheric pressure
absolute pressure
when an oxygen tank is empty and reads “0” is it 0 gauge pressure or 0 atmospheric pressure*
0 gauge pressure
(if pressure was truly 0, it would be collapsed)
the cylinder actually contains O2 at atmospheric pressure or 14.7 psi or 1 bar
what are gas-cylinder pressures, art line pressures, ventilator pressures such as peak inspiratory pressures?
gauge pressures
what is the pneumonic for the gas laws
Prince Charles (pressure) had TB (boyle’s temp) and was given Vitamin G (Volume, Gay Lussac’s)
what is the law:
At a constant temperature, the volume of a given gas varies inversely with the absolute pressure.
boyle’s law of temperature
P1 x V1 = P2 x V2
what is the law:
At a constant pressure, the volume of a given gas varies directly with the absolute temperature.
charles’ law of pressure
V1 / T1= V2 /T2
example: helium balloons on a mailbox shrink in the cold; inflatable cuff of LMA expands in an autoclave
think VTICU. V comes before T
what is the law:
At a constant volume, the absolute pressure of a given mass of gas varies directly with the absolute temperature.
Gay Lussac’s Law of Volume
P1 / T1 = P2 /T2
think physical therapist. P comes before T
when squeezing an ambu bag, does the pressure go higher or lower
higher
is kelvin necessary in the gas laws*
YES
kelvin = celcius + 273
The lower the atmospheric pressure, the _____ the boiling point.
lower
pressure varies DIRECTLY with temp
what is the law:
In a mixture of gases, the pressure exerted by each gas is the same as that it would exert if it was alone in the container.
Partial pressure exerted by any single gas in a combination of gases is directly proportional to its % composition of the gas mixture.
dalton’s law of partial pressures
P1 + P2 + P3 = Ptotal
what is:
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules (a mole).
avogadro’s hypothesis
what is avogadro’s number:
6.022 x 10 to the 23 power
number of atoms/molecules in 1 mole
what is the ideal gas law
PV = nRT
R is the universal gas constant
The gas laws combined with Avogadro’s hypothesis
At STP (standard temp and pressure), one mole of any gas occupies _____ liters
22.4 liters
what is STP
0 C, 760 mmHg, dry (no water vapor)
is nitrous (N2O) a liquid in a cylinder, except for the vapor at the top ?
yes
this is why the pressure gauge does not apply
TRUE OR FALSE
With an oxygen cylinder, as the pressure on the gauge decreases, so also does the amount of gas (moles which determines liters).
TRUE
what is the temperature above which no amount of pressure can liquefy a gas
critical temperature
what is the pressure to liquefy a gas at its critical temperature
critical pressure
what does solubility depend on (4 things)
-partial pressure of the gas
-temp
-gas
-liquid
what is the law:
At a certain temperature, the amount of a given gas dissolved in a given liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid
henry’s law
what is overpressurizing an example of?**
henry’s law
what is this known as?
increase concentration of isoflurane in the blood, the concentration or partial pressure of isoflurane should be increased. This is utilized at the induction of anesthesia when a higher concentration of the anesthetic than necessary for maintenance, or a loading dose, is delivered to speed uptake.
overpressurizing
what law is this an example of?
breathing air under pressure as scuba diver causes more nitrogen into solution in tissues
henry’s law
what is this?
A change in any of the factors in determining an equilibrium causes the system to adjust or reduce or counteract the effect of the change.
Le Chatelier’s principle
think about how when you put a pot to boil on the stove, right before it boils it has little air bubbles at the bottom (this is the gas escaping from the liquid)
what is this an example of?
If patient is cold at the end of an anesthetic, the inhaled anesthetic will be more soluble in the blood, causing the patient to wake up more slowly. (delayed emergence)
Le chatelier’s principle
what is the ratio of the amount of substance present in one phase compared with another (the two phases being of equal volume and in equilibrium)
partition coefficient
what reflects the proportion of the anesthetic that will be absorbed in the blood verses the amount of anesthetic that will leave the blood to diffuse into tissues
blood -gas partition coefficient
The lower the b-g partition coefficient, the _______ the induction
faster
example:
Desmerane gas is .42
this means that .42 dissolved in blood vs 1 dissolved in gas phase. So, it prefers to be in the gas phase.
You want the GAS to build up in the alveoli, then leading to equilibrium with blood, then equilibrium with site of effect.
The lower the b-g partition coefficient, the _______ the soluble/solubility
lower
Low solubility: would rather be in the gas phase; will cause a patient to go to sleep quicker; and rapid emergence (gas being exhaled)
what is the ratio of a gas present in oil verses in the gas state. Indicates how efficiently a gas can access and affect the sites of action.
oil-gas partition coefficient
The higher the oil-gas coefficient (lipid-solubility), the more _____ the anesthetic gas.
example: 243.0
potent
Fat is an important component in cell membranes and neurons. Solubility of gases can be measured in oil which is similar to fat in tissues.
The continual movement of molecules among each other in liquids or in gases.
diffusion
Diffusion occurs from areas of _____ concentration to areas of _____ concentration.
HIGH to LOW
ALWAYS
which law says if there is a greater difference it will diffuse faster
henry’s law
Diffusion is _______ proportional to pressure gradient (P1-P2 OR ΔP) of the gas
directly
the higher the pressure, the greater the diffusion
Diffusion is _______ proportional to surface area (A) of the gas
directly
the greater the surface area, the greater the diffusion
Diffusion is _____ proportional to solubility (S) of the gas
directly
the higher the solubility, the greater the diffusion
Diffusion is _____ proportional to thickness of the membrane (d)
indirectly
the greater the thickness, the less diffusion
Diffusion is _____ proportional to size of the molecule (MW)
indirectly
the greater the size of the molecule, the slower the diffusion
what law is:
The rate of diffusion of a substance across unit area is proportional to the concentration gradient.
D ∞ ΔP x A x S divided by
d x (square root of MW)
Fick’s Law
what law:
explains concentration effect, second gas effect, diffusion hypoxia, expanded air-filled spaces with nitrous**
fick’s law
what is an example of a gas that follows fick’s law?
nitrous oxide
1) second gas effect:
Nitrous is a carrying effect, nitrous will move into the blood phase, sebo will build up faster in the alveoli
2) diffusion hypoxia: eliminated so rapidly that it dilutes the alveolar concentration causing the PaO2 to drop. to prevent this from occurring, administer 100% oxygen at the conclusion of the anesthetic when the nitrous is being eliminated.
3) movement to air-filled cavities: pneumothorax (air somewhere it is not supposed to be); nitrous will move in 34x faster than nitrogen can move out, the air filled space will grow; non expandable spaces will increase pressure
what are examples of cases to not use nitrous oxide due to fick’s laws effects
-ear graft
-pneumothorax
-intestinal surgeries
what law is:
the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight
graham’s law
D ∞ 1 divided by
the square root of the MW
(think, graham cheated and just used a little bit of fick’s law)
internal attractive forces between like molecules trying to stick together in the smallest shape possible
cohesion
(mercury, convex)
Attractive forces between unlike molecules trying to stick to something different
adhesion
(water, concave)
Heating ______ surface tension.
lowers
Cohesive forces at the surface of a liquid that tend to keep liquid in the most compact form?
surface tension
what is the pressure in liquids, static (not moving)
P= h x dw
(P= height of column x density weight of liquid)
think of an art line is not very compressible, essentially static, so that pressure can be transmitted easier
what is the number to
convert cm H2O to mmHg: 0.___
0.74 x ___ H2O = _____ mmHg
what is the number to
convert mmHg to H2O: ____
1.36 x _____mmHg= ____H2O
what is:
The quantity of a fluid passing a point in a given time.
flow
F= Quantity / time
F= Q/t
Fluid movement in smooth layers with no turbulence or eddies.
Usually moves in smooth straight channel at low rates of flow.
laminar
Flow is ______ in the center; as it comes closer to the wall of the channel, it becomes _______.
Flow is greatest in the center; as it comes closer to the wall of the channel, it becomes slower.
Flow is no longer smooth, but with swirls, eddies.
resistance is increased.
requires greater pressure gradient.
turbulent flow
when does laminar flow change to turbulent flow?
when critical velocity is reached, direction is changed, diameter is abruptly changed, or flow is obstructed, resistance is increased.
examples: kink in ET tube, stop-cock, Y connector of circuit kink
Resistance is what 4 things
1) Diameter/radius of the channel (r)
2) Length of the channel (L)
3) Nature of the flow – laminar vs. turbulent
4) Viscosity of the fluid (n)
what is the Hagen-Poiseuille equation derivative
deals with resistance
Resistance = 8nL/πr(to the fourth power)
-n is viscosity which is directly proportional to resistance
-L is the length of the channel which is directly proportional to resistance
-8 is a constant
-r is radius of the channel which is inversely proportional to the resistance to the fourth power.
what will have the biggest impact on flow
radius
who is more effected by edema in airway, infant or adult?
infant
smaller radius
can Poiseuille’s law be used to predict resistance to flow once turbulence occurs?
NO
what is:
Given a channel with a narrowing which then increases, the pressure measured along the channel is lowest at the narrowest point, often below atmospheric.
Narrowing causes increased velocity, thus increased kinetic energy. To maintain unchanged sum of energy, the potential energy must decrease.
bernoulli effect
(think venturi, both end in “i”)
plane movement
as kinetic energy (velocity) increases, potential energy (pressure) __________
decreases
surfactant lowers surface tension in alveoli and prevents the effects of _____ Law
Laplace’s Law
(think, you are tense when you work in law)
what law is:
Relationship of wall tension, pressure, and radius of cylinders (vessels) and spheres (ventricles and alveoli*)
Laplace’s law
Cylinders: Tension = Pressure x radius
Spheres: 2T = Pr
(think “the last PLACE i want tension is in an aneurysm)
what is the kinetic energy of molecules of substance
heat
1 kCal is equal to
1 kcal = C = 4184 joules
energy to increase temperature of 1 kg H2O 1 degree C
1cal= 4.18 joules
The parameter used to describe the amount of heat possessed
temperature
is there a degree sign for kelvin
no
at this temperature, all atomic motion ceases
0 kelvin
Heat is a form of energy and can be converted to other forms of energy, but neither created nor destroyed.
1st law of thermodynamics
Heat always flows from warmer to cooler. There must exist a difference in temperature and the two things must be in contact.
2nd law of thermodynamics
what are the 4 methods of heat transfer
Conduction
Radiation
Convection
Evaporation
Heat movement through a substance by the transfer of kinetic energy from molecule to molecule.
conduction
metals are GREAT, air is POOR
2% heat loss for patients
Heat transferred from warmer to cooler objects by emission and absorption of energy radiated in varying wavelengths.
radiation
what accounts for the largest percentage of normal heat loss from the body
radiation
40%
Heat transfer occurs by moving fluid (liquid or gas).
convection
32%
bair hugger
wind chill
heat transfer by vaporization of moisture on the skin’s surface.
evaporation
28%
surgical wounds
respiratory tract
sweating
the heat required to change liquid into vapor (gas)
Latent heat of vaporization
The amount of heat required to raise the temperature of 1 kg of a substance by 1 kelvin.
specific heat capacity
Energy required to convert 1 kg of a substance from one phase to another at a given temperature (J/kg).
specific latent heat
the heat required to change a solid to a liquid
Latent heat of fusion
what effect is this?
When volatile inhalation agents change from liquid to vapor, it requires heat, causing the remaining liquid and the walls of the vaporizer to cool (lose heat)
When a N2O (nitrous) cylinder is allowed to empty rapidly, the cylinder becomes very cold and the water vapor from the surrounding air freezes on the cylinder.
Joule Thompson effect
(think “Joule is cool”)
what determines the isotope and the stability of the nucleus (proton, neutron, or electron)?
neutron
what determines the element (proton, neutron, or electron)?
proton
what happens with an unstable isotope
Beta particle (electron) may be emitted.
The nucleus may attract and capture an electron.
Alpha particle is lost consisting of two protons and two neutrons.
The nucleus may split into several parts
what type of electromagnetic radiation:
releases energy by removing electrons from atoms in tissues.
Creates ions that are very chemically reactive and very hazardous.
Includes x-rays and gamma rays released by radioactive isotopes.
ionizing
what type of electromagnetic radiation:
Discharges its energy without creating ions or removing electrons from atoms in tissues.
Includes infrared radiation, visible light, ultraviolet radiation as utilized with lasers.
LASER – light amplification by stimulated emission of radiation.
nonionizing
IONIZING:
the intensity of scattered radiation is _______ proportional to the square of the distance from the source.
inversely
Distance is the best form of protection: at least 3 feet away.
what helps prevent ionizing radiation
distance
time
shielding
what is the maximum yearly occupational exposure to ionizing radiation
5000 mrem OR 5 rem
pregnancy <500 mrem
what types of cells are most susceptible to radiation?
actively dividing cells
tumors and fetal cells
what helps prevent nonionizing radiation
eyewear (including the patient!)
instruments that are nonreflective (matte)
filter mask (debris size range from 0.1 to 0.8 um), HPV and HIV can be found in the plume
what is
solubility increases with decreasing temp
Le Chateliers Principle
