ChemPhys Review Flashcards
Molecular Theory of Matter
states that matter is made of minute particles called molecules, that exist in various states (solid, liquid, gas, or plasma)
Kinetic Theory of Matter
states that molecules are in constant motion (random motion) and have a degree of attraction between them called van der waals forces.
Critical Temperature
the temp. above which a gas cannot be liquefied regardless of how much pressure is applied
Liquid; compressability
Liquids have minimal to no compressibility, volume MAY change with change in pressure or temperature
Gases; compressability
Gases are easily compressible
Easily change volume with changes in pressure or temperature
Structural Isomers
Have the same molecular formula, but their atoms are located in different places.
Structural isomers are truly different molecules with differing physical and chemical properties
(Enflurane and isoflurane are examples of structural isomers)
Stereoisomers
molecules that have a similar geometric arrangement of atoms but differ in their spatial position.
may be enantiomers or diastereomers .
Enantiomers
Stereoisomers that are mirror images of each other but cannot be super imposed.
Possess similar chemical, physical properties.
Enantiomers are optically
active, can rotate light either clock wise or counter clockwise.
Clockwise = dextro
Counter clockwise = levo
Diasteromers
are not mirror images, and may have differing physical and chemical properties.
In liquids, gas solubility is inversely related to
temperature
As temperature increases, LESS gas is dissolved in a liquid.
R/t increased kinetic energy of gas molecules.
Hypothermic patients and emergence
Hypothermic patients have a slower emergence r/t their decreased body temperature.
Colder temp = more gas is able to dissolve in blood.
Gas solubility in a liquid is directly related to
Pressure.
Henry’s law, more pressure = greater solubility of gases in liquids
Henry’s Law states
At a constant temperature, the amount of gas dissolved in a liquid is directly proportional to the partial pressure of the gas in contact with the solution`
Henry’s law allows calculation of
dissolved O2 and CO2 in blood
Formula for deriving oxygen content in blood
PaO2 X solubility co-efficient
PaO2 x 0.0031
Formula for deriving oxygen contenting blood
PCo2 x solubility co-efficient
PCo2 x 0.067
Formula for oxygen delivery
DO2 = CO x (1.34 X SaO2 x hgb) + (PaO2 x 0.0031) x 10
Overpressuring:
increase the concentration set on the vaporizer of pressure of gas to speed up delivery to the blood and, therefore, the brain
Application of Henry’s Law
Graham’s Law
A gas diffuses at a rate that is inversely proportion to the square root of its molecular weight
As molecular weight increases, diffusion
decreases.
As molecular weight increases the rate of diffusion decreases.
Smaller molecules diffuse
faster
nitrous oxide is contraindicated in patients with
pneumothorax,
or another air filled cavity where expansion is undesirable.
ex. abdominal surgery.
Diffusion
the net movement of one type of molecule through space as a result of random motion to minimize a concentration gradient
Diffusion of gases across a biological membrane is expressed by
Fick’s Law
Fick’s law states that
diffusion of a gas across a semipermeable membrane is directly proportional to the partial pressure gradient, the membrane solubility of the gas, and the membrane area, and is inversely proportional to the membrane thickness and the molecular weight of the gas.
Clinical Application of Fick’s Law (5)
Allows determination of pulmonary gas exchange
Diffusion Hypoxia
COPD - reduced alveolar surface tension, slower induction
Placental Drug Transfer
2nd gas effect
Diffusion Hypoxia
During emergence from nitrous oxide anesthetic, rapid elimination of nitrous oxide from the lungs dilutes other alveolar gases, producing alveolar “diffusion hypoxia.” This phenomenon is driven by the same mechanism as the second gas effect—but in the reverse direction
too much nitrogen being exhaled, dilutes other gases, leads to hypoxia
1 torr
1 torr = 1 mmHg
1 kPa
10.2 cm H2O = 7.5 mmHg/7.5 torr
1 atm =
760 mmHg = 1 bar = 14.7 PSI = 1020 cmH20
Compared to the volume of nitrogen diffusing out
the volume of nitrogen diffusing in is greater
Boyle’s Law =
P1V1 = P2V2
with Boyle’s Law, the volume is
inversely proportional to the pressure
As pressure increases, volume decreases
Charles’ Law =
V1/T1 = V2/T2
Charle’s law states that
When pressure and n are constant, increase in volume is directly proportion to increase in temperature
Gay-Lussac’s Law
P1 / T1 = P2/T2
Gay - Lussac’s Law states
when volume is held constant, an increase in pressure is directly proportional to an increase in temperature.
Avogadro’s #
6.022 e 23
If you have two different containers of two different gases as the same temperature and pressure then you can assume
they contain the same number of molecules.
Calibration of vaporizes is done using
Avogadro’s Hypothesis
Dalton’s Law
The total pressure of a gas mixture is the sum of the partial pressure of each gas
Critical temperature of oxygen
-119 celcius
Critical temperature of nitrogen
~ 36.5 - 39.5 celcius
Poisueille’s Law describes
the relationship between rate of flow and
pressure gradient, (direct)
radius^4 of tube,(direct)
length of tube,(inverse)
viscosity. (inverse)
Applications of Poisueille’s Law (4)
IV flows (blood)
Airways (ex. heliox)
Vascular flow - (anemia vs polycythemia)
thorpe tubes (at low flows) hence laminar flow
Poisueille’s law is applied with
LAMINAR flow
Factor will have the most dramatic effect on flow according to Poisueille’s law
radius of tube
viscosity is
the inherent property of a fluid that resists flow
Reynold’s number determines
laminar vs turbulent flow.
> 2000 = turbulent
<2000 = laminar
Reynold’s Number Equation
(velocity) x (density) x (diameter) // viscosity
Factors that change flow from laminar to turbulent
- increased velocity
- bend >20 degrees
- irregularity in the tube
turbulent flow often occurs in (airways)
medium to large airways, predominates phonation, coughing, peak flow
Smaller bronchioles can maintain
laminar flow
Reynolds number is an index that incorporates
Poiuselles law and density
Reynolds number is directly proportional to
velocity, density, diameter
Reynolds number is inversely proportional to
viscosity
Reynolds number application:
Heliox. Has a much lower density than nitrogen helps restore laminar flow to constricted airways
Bernoulli’s Theorem relates
pressure and velocity
Increased velocity = decreased pressure.
Therefore narrow diameter = increased velocity = decreased pressure
Venturi Effect
The lateral pressure of rapidly flowing fluid in a constricted tube can be sub-atmospheric, hence a sidearm on that portion of the tube can be used to aspirate another fluid into the tube
Clinical Applications of Bernoulli and Venturi
Nebulizers
Venturi Masks
Jet Ventilation
With Venturi effect air/gas are entrained
Air may be entrained into a flow of liquid,
or a liquid may be entrained into the flow of a gas.
Conada effect explains
tendency of fluid flow to follow a curved surface upon emerging from a constriction.
will choose the path that is slower to return to increased pressure.
La of LaPlace formula
tube = Tension = Pressure x radius
sphere = 2Tension = Pressure x Radius
La of Laplace relates
Pressure gradient across the wall of a SPHERE or TUBE/CYLINDER (blood vessel, ventricle, alveolus) is directly related to tension and
inversely related to radius
La Place’s law directly applies to alveoli in the absence
of surfactant
without surfactant, small alveoli
would collapse as they would require higher pressure to open compared with larger alveoli
Surfactant Lowers the surface tension more in
smaller alveoli r/t having a more concentrated effect
Applications of La Place’s Law
alveoli + surfactant
vascular pathology (aneurysms)
ventricular volume and work of the heart
Clinical applications of Ohm’s LAw
strain gauges in pressure transducers
thermistors
Aneursyms are more likely to rupture because
they will have a greater tension along the part with a wider radius compared to the rest of the vessel
1 dyne =
force required to move 1 g of weight 1 cm per second
osmotic pressure vs oncotic presssure
oncotic pressure = osmotic pressure exerted by a plasma protein
osmotic pressure = force needed to stop osmosis from occurring.
Reynolds number equation
velocity x density x diameter / viscosity
