RE Chapter 14 Flashcards
Graham’s Law
The rate of gas diffusion through an orifice (effusion) is inversely proportional to the square route of its molecular weight
r=1/√ mw
*faster diffusion for smaller molecules
Henry’s Law
At a constant temp, the amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas at equilibrium above the gas-liquid interface
p=kc
**(p is partial pressure, k is henry’s constant, c is concentration of solute in solution)
What five factors determine diffusion?
Directly proportional: concentration gradient, tissue area, fluid tissue solubility
indirectly proportional: membrane thickness, molecular weight
What is osmosis?
The movement of water across a semipermeable membrane to equilibrate a concentration gradient
What is osmotic pressure?
The force needed to stop osmosis
What is oncotic pressure?
The osmotic pressure by plasma proteins & electrolytes in capillaries.
What is normal oncotic pressure?
28 mmhg
Fick’s Law
Diffiusion of a gas across a semipermeable membrane is directly proportional to the partial pressure gradient, membrane solubility of the gas, & membrane area. It is inversely proportional to the membrane thickness and molecular weight.
Fick equation for diffusion of respiratory gases
J=αD/∆x(Pao2 - Pacapo2)
J - diffusion flux α - solubility constant for o2 D - diffusivity ∆x - membrane thickness (Pao2-Pcapo2) - alveolar-capillary o2 partial pressure difference
What is the force of gravity?
9.81 m/sec/sec
One newton =
1/9.81 kg wight or 102 g weight
What is the formula for force?
F=ma
m-mass
a-acceleration
What is a dyne?
1/1000th of a newton
Normal PVR
100 - 200 dyne sec/cm^5
Formula for calculating SVR
80 x (MAP-CVP)/CO
Normal SVR
900-1200 dyne sec/cm^5
Definition of pressure
force over area
P = f/a
What is a pascal?
Standard unit of measurement
Pa=1 N/ 1 m²
1 torr = _____ mmHg
1
1 kPa = ______ cm H2O = _______ mmHg
1 kPa = 10.2 cm H2O = 7.5 mmHg
gage pressure =
absolute pressure - atmospheric pressure
at sea level, 760-760= 0
What is absolute zero?
0º K
Celsius to kelvin
K = C + 273
Celsius to Fahrenheit
F = 1.8(C) + 32
What is standard temperature?
273.15 K (0º C)
What are the 4 primary mechanisms of body heat loss?
- Radiation
- Convection
- Conduction
- Evaporation
What is the most common source of heat loss? The least?
Most common is radiation, least is evaporation
What is latent heat of vaporization?
the amount of heat energy per unit mass required to convert a liquid into the vapor phase.
The rate of vaporization depends on what three things?
- Temperature
- Vapor pressure of the liquid
- Partial pressure of the vapor above the evaporating liquid
Vapor pressure of isoflurane
238 mmHg
Vapor pressure of sevoflurane
160 mmHg
Vapor pressure of desflurane
660 mmHg
Universal Gas Law
PV=nrT
P-pressure V-volume n-number of moles r-constant T - temp in K
r (constant in universal gas law) =
0.08221 L x atm / K / mol
One mole of any gas at 0º C will expand to _____ liters volume
22.4 (standard molar volume)
With n held constant the universal gas law is….
P1V1/T1 = P2V2/T2
Boyle’s law
Pressure & Volume are indirectly proportional
P1V1=P2V2
Charles law
Temperature and volume are directly proportional
V1/T1 = V2/T2
Gay-Lussac’s Law
Pressure and Temperature are directly proportional
P1/T1 = P2/T2
Avagadro’s number shows that a mole of any gas has ________ molecules
6.023 x 10^23
Dalton’s gas law
The total pressure of a system is the additive pressures of each individual gas in a mixture
Pgas = Pa+Pb+Pc…
How do you determine the partial pressure of a gas based on dalton’s law?
P(gas) = (volume %) x Ptotal
ex: medical air (79% nitrogen& 21% air) Ptotal is 760 mmHg
Pnitrogen = .79 x 760 = 600.4 mmHg
Po2 = .21x760 = 159.6 mmHg
What is the definition of flow?
The quantity of fluid passing a point per unit time
F = Q/t
What is laminar flow?
type of flow in which all molecules of a fluid travel in parallel within the tube. The molecules in the center move at a velocity twice as fast compared to flow at the walls.
In what part of the airways do you see laminar flow?
The terminal bronchioles (smallest airways)
What type of flow does poiselle’s law describe?
Laminar
Equation for poiselle’s law
F=(πr⁴∆P)/(8nl)
r⁴ - radius to the 4th power
n - viscosity of fluid
∆P - pressure gradient
l - length of tube
According to poiselle’s law _____ will have the most dramatic effect on flow.
radius
doubling the radius will result in a ____-fold increase in flow, tripling the radius will result in a ______-fold increase in flow.
doubling - 16-fold increase
tripling - 81-fold incerase
What does reynolds number determine?
Whether a given flow will be laminar or turbulent.
What is the equation for reynolds number?
vpd/n
v-velocity
p-density
d-diameter
n-viscosity
What does a reynolds number of greater than 2000 indicate? less than 2000?
> 2000 = turbulent flow
<2000 = laminar flow
What does the bernoulli principle describe?
In a tube containing a constriction, at the constriction the velocity of flow increases and there is a corresponding decrease in pressure at the narrowing.
What does Laplace’s law describe?
The relationship of wall tension to pressure and radius in cylinders & spheres
Laplace’s law equation for a cylinder
T = Pr
T-tension
P-pressure
r-radius
Laplace’s law for a sphere
2T=Pr
What unit is tension measured in?
N/cm
100mmHg=______N/cm²
1.33
What are transverse waves? Name an example.
Composed of up-and-down movement
ex. electromagnetic radiation waves
What are longitudinal waves? Name an example.
composed of back-and-fourth movements along the direction of the wave. These are pressure fluctuations
ex. sound waves
What is impedance?
The total of all forces that impede electrical flow
What is capacitance?
The capacity to store charge
What is electromagnetic inductance?
transfer of electric current between circuits without physical contact, using magnetic waves.
What is macroshock?
large amounts of current conducted though a patient’s skin.
macroshock of ___ -___mA can cause ventricular fibrillation
100-300
What is microshock?
The delivery of small amounts of current directly to the heart.
What level of microshock may cause ventricular fibrillation in humans?
100 μA
In pulse oximetry oxygenated hemoglobin absorbs ________(infrared/visible red) to a wavelength of _____ nanometers.
infrared / 940 nanometers
In pulse oximetry deoxygenated hemoglobin absorbs _______(infrared/visible red) frequency at a wavelength of _____ nanometers
visible red / 660
SaO2 of 90% corresponds with a PaO2 of ______ mmHg
60
SaO2 of 70% corresponds with a PaO2 of ________ mmHg and cyanosis is apparent
40
The physical sharing of electrons between atoms is called a ______ bond.
covalent
What are isomers?
Molecules that have the same chemical formula but different structural formulas.
What are hydrocarbons?
Molecules composed entirely of carbon atoms with hydrogen atom attached
What are alkanes?
hydrocarbons containing only single-bonded carbon atoms.
What is a saturated hydrocarbon?
Single-bonded carbon chains with all available carbon bonds attached to hydrogen
What is an unsaturated hydrocarbon?
One or more double/triple bonds between carbon atoms.
What is an alkene?
Hydrocarbon containing double bonded carbons.
What is an alkyne?
triple-bonded hydrocarbons
Amine
NR3 (only 1 or two of the Rs may be hydrogen)
Derivatives of ammonia (NH3)
Alcohols
ROH - R represents an alkyl group
Phenols
ROH - R represents an aryl group (benzene)
Ethers
ROR’ - where R and R’ are alkyl groups attached by O2
Carbonyl group
C=O key component in aldehydes, ketones, carboxylic acids, esters, and amides
Aldehydes
RCHO
Ketones
RCOR’
Carboxylic acids
RCOOH
Esters
RCOOR
Amides
RCONH2, RCONHR, or RCONR2
Normal Axis Deviation
-30º to +90º
Lead I = positive
Lead aVF = positive
Left Axis Deviation
-30º to -90º
Lead I = positive
Lead aVF = negative
Right Axis Deviation
+90º to +/- 180º
Lead I = Negative
Lead II = Positive
Superior Right Axis Deviation
-90º to +/-180º
Lead I = negative
Lead aVF = negative
