Gas Laws
Henry, Fick, & Graham
Flow
Ohm's, Laplace, & Dalton
Misc.
100
Which law is represented by the following equation: P1/T1 = P2/T2
Gay-Lussac's law
- Volume is constant
- Temperature & pressure of a gas are directly proportional: heated gas tends to increase the pressure in a container
O2 tank explodes in a hot environment
100
The amount of gas that dissolves in a solution is directly proportional to the partial pressure of that gas over the solution - whose law?
Henry's law
- The higher the gas pressure, the more it will dissolve into a liquid (assuming a constant temperature)
- Partial pressure & temperature affect solubility (^ pressure, ^ solubility; ^ temperature, v solubility)
- Application: anesthetic emergence is prolonged in the hypothermic patient because the solubility of the gas is increased
100
What equation is used to determine what type of flow will occur in a particular situation?
Reynold's number (Re) = density x diameter x velocity / viscosity
- 3 types of flow: laminar, turbulent, & transitional
100
Law that states that the total pressure is equal to the sum of the partial pressures exerted by each gas in the mixture.
Dalton's Law
- Ptotal = P1 + P2 + P3 ....
100
Which type of molecular bond is the strongest?
Covalent
- Covalent > Ionic > Hydrogen Bond > Van der Waals
- Covalent: equal sharing of electrons
- Ionic: complete transfer of electrons
- Hydrogen: unequal sharing of electrons
200
Which law is represented by the following question: V1/T1 = V2/T2
Charles's law
- Pressure is constant
- Volume & temperature of a gas are directly proportional: heated gas tends to expand
200
The rate of diffusion of a gas is inversely proportional to the square root of the gas's molecular weight - whose law?
Graham's law
- Smaller molecules diffuse through a membrane faster than larger molecules
- Application: second gas effect
200
What type of airflow is seen in the terminal bronchioles?
Laminar flow
- Laminar flow: Re < 2,000, travel in parallel pattern, fastest in center
- Turbulent flow: Re > 4,000, travel in chaotic pattern, flow through glottis, carina, & medium-sized airways
- Transitional flow: Re 2,000 - 4,000, turbulent pattern in center & laminar pattern near walls of the tube
200
Law that illustrates the relationship between the wall tension, internal pressure, & radius in spheres and cylinders?
Law of Laplace
- Spheres: tension = pressure x radius / 2 (alveolus)
- Cylinders: tension = pressure x radius (blood vessels)
200
Three ways to limit radiation exposure.
Distance
Duration
Shielding
300
Which law is represented by the following equation: P1 x V1 = P2 x V2
Boyle's law
- Temperature is constant
- Volume & pressure of a gas are inversely proportional: as the volume decreases, the pressure increases
- Application: Pneumatic bellows, diaphragm contraction increases Vt
300
Whose law can be applied to the concept of diffusion hypoxia?
Fick's Law of Diffusion
- Rate of transfer is directly proportional to: partial pressure difference, diffusion coefficient, & membrane surface area
- Rate of transfer is inversely proportional to: membrane thickness & molecular weight
- Application: diffusion hypoxia, drug transfer across the placenta
300
According to Poiseuille's law, flow is inversely proportional to?
Viscosity & length of tube
- 
300
Which law states that the current passing through a conductor is directly proportional to the voltage and inversely proportional to the resistance?
Ohm's law: current = voltage difference / resistance
- Adapt to understand fluid flow: flow (CO) = pressure gradient (MAP - CVP) / resistance (SVR)
300
Radiation exposure obeys which law?
Inverse square law: intensity = 1 / distance2
- The amount of exposure is inversely proportional to the square of the distance of the source
400
Which law is represented by the following equation: PV = nrT
The Ideal Gas Law
P = pressure
V = volume
n = number of moles
r = constant 0.0821 L-atm/K/mole
T = temperature
- Can be reduced to P = T / V
400
How much CO2 is dissolved in the blood with a PaCO2 of 40?
2.68
- CO2 solubility coefficient = 0.067 mL/dL/mmHg
- 40 x 0.067 = 2.68
- CO2 is 20x more soluble than O2
400
Altering the _____ of the tube exhibits the greatest impact on flow. Why?
Radius because it is raised to the 4th power
400
Which law is an adaptation of Ohm's law to incorporate vessel diameter, viscosity, & tube length?
Poiseuille's law
400
What is the critical temperature of oxygen?
-119C
- Critical temperature: highest temperature where a gas can exist as a liquid (highest to lowest)
- Nitrous oxide 36.5C (liquid in cylinder at room temp)
- Carbon dioxide 31C (liquid in cylinder at room temp)
- Oxygen -119C
- Air -140C
- Nitrogen -147C
500
Which law explains why a LMA cuff ruptures when placed in an autoclave?
Charles's law
- Mnemonic to remember which variables remain constant in each law: Paid TV Can Be Good (pressure is held constant in Charles's law)
P T V
C B G
500
What is the solubility coefficient of oxygen? Whose law is this?
0.003 mL/dL/mmHg, Henry's Law
- Each gas has a unique solubility coefficient which represents how easily a gas can be put into a solution
- Used to calculate O2 delivery. DO2 = CO x [(1.34 x hgb x SpO2) + (PaO2 x 0.003)] x 10
- We apply Henry's law when we increase FiO2
500
During laminar flow, quadrupling the radius will cause flow to increase by?
256x increase in flow
- r = 4 x 4 x 4 x 4
500
What substance modulates surface tension and prevents alveolar collapse?
Surfactant
- Produced by type 2 pneumocystis beginning at 22-26 weeks and peaking at 25-36 weeks gestation
- Smaller alveoli have a relatively higher concentration, preventing them from collapsing into larger alveoli
- Law of Laplace: tendency of an alveolus to collapse is directly proportional to surface tension (more tension, more collapse) & inversely proportional to alveolar radius (smaller radius, more collapse)
500
Explains why an oxygen cylinder that is opened quickly feels cool to touch.
Joule-Thompson Effect