Anesthesia Final3
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- Gauge pressure vs absolute pressure:
- P(absolute)= P(gauge) + P (atm)
- SI unit of pressure
- pascal (Pa)
- pressure of one newton acting over one square meter
- one pascal (1 Pa)
- approximate atmospheric pressure at sea level
- 1 bar 100 kPa 760 mmHg 760 Torr 14.5 psi 1 atm
- what is the formula for pressure?
- P = f/a where P = pressure f = force a = area
- type of flow in which fluid has no eddies or turbulence
- laminar
- One mole of any gas at STP occupies what volume?
- 22.4 L
- Molec wt of N2O
- 44
- Hagen-Poiseuille equation
- Q = (Ϭ P d^4) / (128 η l) where Q = flow Ϭ = 3.14... P = pressure d^4 = tube diameter raised to the 4th power η = viscosity l = tube length
- equation which describes the effect of pressure, tube length/diameter, and viscosity on laminar flow
- Hagen-Poiseuille equation
- what effect does surfactant have on Laplace's Law
- It reverses it. Surface tension= r/2T
- Reynolds number equation
- Reynolds number = vρd/η where v = linear velocity ρ = density d = tube diameter η = viscosity
- the fluid property that is involved in turbulent flow is:
- density
- This fluid property is involved in laminar flow:
- viscosity
- type of flow usual in lower respiratory tract
- laminar
- type of flow usual in upper respiratory tract
- turbulent
- Laplace's law for sphere
- P = 2 X T / r where P = pressure T = surface tension r = radius
- Molec wt of He2
- 4
- fall of pressure after a constriction in a tube
- Bernoulli effect/venturi effect
- tube which takes advantage of Bernoulli effect to entrain gases or nebulize liquids
- Venturi tube
- tendency of stream of fluid or gas to continue to flow along a convex surface
- Coanda effect
- states that at constant temperature the volume of a given mass of gas varies inversely with the pressure
- Boyle's Law
- What is entonox?
- 50/50% O2/N20 mix
- states that at constant pressure the volume of a given mass of gas varies directly with the temperature
- Charles' Law
- Formula to convert F to C:
- Tc= 5/9 (F-32)
- statest that at constant volume the pressure of a given mass of gas varies directly with the temperature
- Third Perfect Gas Law OR Gay Lussac's Law
- Formula to convert C to F:
- Tf= (9/5 C) +32
- a change in the volume and pressure of the contents of a system without exchange of heat between the system and its surroundings
- adiabatic change
- states that in a mixture of gases the pressure exerted by each gas is the same as that which it would exert if it alone occupied the container
- Dalton's Law of Partial Pressures
- states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules
- Avogadro's hypothesis
- Avogadro's number
- 6.022 X 10^23
- Universal Gas Constant equation
- PV = nRT where P = pressure V = volume n = moles R = constant T = temperature
- temperature above which a gas cannot be liquified however much pressure is applied
- critical temperature
- the pressure at which a vapour will liquify, in a substance below it's critical temperature
- critical pressure
- critical temperature at which a gas mixture may separate into its constituents
- pseudocritical temperature
- process in which the rate of change of a quantity at any time is proportional to the quantity at that time
- exponential process
- the time a process would have been complete had the initial rate of change continued
- time constant
- molec wt of N2
- 28
- partial pressure of a vapor in a closed container and at equilibrium with the liquid phase
- vapor pressure
- states that at a particular temperature the amount of a gas dissolved in a liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid
- Henry's Law
- the volume of a gas which dissolves in one unit volume of a liquid at the temperature concerned
- Ostwald solubility coefficient
- 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
- another word for partial pressure for gases in a solution
- tension
- the physical state of a substance above it's critical temperature
- a gas
- a substance in its gaseous phase below its critical temperature
- a vapor
- Dalton's Law equation
- Pmixture = P1 + P2 + P3...
- fall of alveolar oxygen concentration as a result of the dilution of alveolar oxygen by excretion of nitrous oxide
- diffusion hypoxia
- increase in concentration (partial pressure) of a gas in the alveoli when a more soluble gas diffuses quickly into the bloodstream - results in increased rate of diffusion for the second gas
- second gas effect
- point at which 50% of patients cease to move in response to a stimulus
- MAC (minimum alveolar concentration)
- rate of diffusion of a substance across a surface or membrane is proportional to the concentration gradient
- Fick's Law
- states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight
- Graham's Law
- states that depression or reduction of vapor pressure of a solvent is proportional to the molar concentration of the solute
- Raoult's Law
- a mixture which vaporizes in the same proportions as the volume concentrations of the components in solution
- azeotrope
- pathway with length greater than width
- tube
- pathway with width greater than length
- orifice
- point at which increased pressure results in turbulent flow but below which flow is laminar
- critical point
- variable orifice flowmeter
- Thorpe tube
- property of He which makes it useful for decreasing resistance to flow through narrowed lower airways
- low density
- force per area of molecules in a liquid as they interface with the gas above it
- vapor pressure
- to determine time left on a cylinder of nitrous oxide, you must determine the volume of gas available from both...
- the liquid phase and the vapor phase
- unit of measure for osmotic activity
- osmole
- 6.02 X 10^23 particles of dissolved solute that cannot diffuse through a semipermeable membrane
- 1 osmole
- pressure exerted by 1 gmw of a nonionizing, nondiffusible solute in 22.4L of water
- 1 atm
- pressure exerted by 1gmw of a monovalent, ionizing, nondiffusible solute in 22.4L of water
- 2 atm
- states that even in isolation from the environment, a gas cools when expanded and warms when compressed
- Poisson adiabatic equation
- Which of the following does NOT affect rate of laminar flow? pressure gradient, fluid viscosity, tube length, fluid density, tube diameter
-
pressure gradient.
reynolds # is:
(velocity x density x diameter)/(visc x length) - At low rates of flow, the orifice of a variable orifice flowmeter is more like what?
- a tube
- tendency toward turbulence increases when this fluid property is increased
- density
- tendency toward turbulence decreases when this fluid property is increased
- viscosity
- As tube diameter is doubled, rate of flow _________ by a factor of _____.
- increases, 16
- As tube length is halved, rate of flow ____________ by a factor of _____.
- decreases, 2
- molec wt of H2
- 2
- molec wt of CO2:
- 44
- critical temp for N2O
- 36.5 C
- What is weight?
- A function of the effect of gravity on mass.
- Explain relationship of densities of H2O to Hg:
-
Hg is 13.6 times more dense than H2O.
1kPa = 7.5 mmHg
1kPa = 10.2 CM (102 mm)H2O - what is a racemic mixture:
- an optically neutral mixture of 2 stereoisomers that has different properties than if it were all one stereoisomer alone.
- hydrogen bonds:
- Intermolecular attraction caused by ionic (unequal) sharing of electrons on water molecules; causes a dipolar molecule.
- Vanderwaals Forces:
- weak interatomic attractions caused when two uncharged atoms are in close proximity due to random variability of electron location around the atoms. Plays a key role in DNA and protein structure and folding.
- What is an isotope:
- All similar atoms have same # of protons and electrons. Isotopes have different # of neutrons.
- Convert C to Kelvin:
- K = C + 273
- What are ionic bonds?
- Highly electronegative atom *unequally shares electrons with a less EN atom.
- What is a covalent bond?
- Equal sharing of electron(s) between atoms.
- What is the critical temp of O2?
- -118 C
- What does the solubility coefficient of a gas mean?
-
the #cc of gas that will disolve in a unit/vol of liquid at a stated temp & pressure.
Ostwald Solubility Coefficient - What is a mole measuring?
- the number of atoms in one gram molecular wt of substance.
- What is a stereoisomer?
- Has same molecular "ingredients" but is arranged differently. May have different physical or chemical properties.
- Define vapour pressure:
- the pressure exerted by the molecules in a liquid as they interface with the surface of the liquid.
- What is the vapor pressure of H2O?
- 47mmHg
- When looking at a Bourdon gauge, how can you determine Psia?
- add the Psig of the gauge to the Psia (14.7psi at sea level).
- What is the formula for an exponential process?
- y=x^2. or y=k^x (variable exponential process)
- How much of of the original amount of substance is left after one time constant if the process is a true y=x^2 negative exponential process?
- 37% of original
- What is an example of a "washout curve" / negative exponential process?
- thermodilution measurement of cardiac output.
- What is an example of a positive exponential process?
- Bacterial or tumor growth.
- What is a build up exponential process and how does it differ from positive exponential process? Give an example:
- The rate of change is initially rapid but slows toward the end. An example is lung filling.
- Why is Ostwald's solubility coefficient more useful for CRNAs?
- It is given at a known (practical) temp and is independent of pressure.
- Explain why a highly soluble anesthetic like ether is less potent than N2O which is (relatively)less soluble:
- The ether crosses the alveocap mem instantly and does not allow alveolar partial pressure of ether to develop. The ether is highly soluble so it wants to stay in the blood and doesn't move into the brain tissue readily. The N20, on the other hand, rapidly builds up a high alveolar pressure gradient and begins "forcing" the N2) into the blood even though it isn't as soluble and doesn't want to be there. Because it isn't as soluble, it "pops" out of solution into the brain tissue readily. Hence, it is more potent.
- Explain Ficks law in laymans terms:
- the rate of diffusion of a substance across a membrane is proportional to the concentration gradient: this means that if you have 10 marbles and 5 will move across a membrane in one minute, if you have 20 marbles then 10 will move across in one minute. It's just a function of how much you have available to move at any one time.
- What does Raoult's Law say?
- the depression or reduction of vapour pressure of a *SOLVENT is proportional to the molar concentration of the *SOLUTE.
- Explain Raoult's Law now in laymans terms:
- the more salt you add to a bucket of water, the less water vapour in equilibrium over the surface of the water. That's because the salt molecules interfere with the water molecules interacting with the surface. Makes sense, eh? (Gary!)
- What is "work" (physics)?
- it is when "the point of application of a force moves in the direction of the force."
- What is the SI unit of work?
- one Joule = N/m
- What is the definition of "power"?
- Power is the *rate of work.
- What is the SI unit of power?
-
the watt.
1 W = 1 J/sec - What does osmolality tell you?
- it is the unit of measure for osmotic activity, so tells you the pull that it has on water.
- How much of a substance would make a 1 Osm concentration?
-
One Avogadro's # of that molecule = 1 Osm.
In 1 L of solution. - You put 1 Gram*atomic wt of glucose in a liter of H2O. What is it's osmotic pressure?
- 1 osm/L
- You put 1 Gram*atomic wt of NaCl in a liter H2O. What is the osmotic pressure?
- 2 osm/L (the NaCl seperates into Na and Cl).
- What is the rule of thumb for calculating osmotic pressure?
- at zero degrees Celcius 1 GMW of any substance dissolved in 22.4 L of water will exert a pressure of 1 atm.