Question Answer
Avogadro’s Law Equal volumes of ideal or perfect gases, at the same temperature and pressure, contain the same number of particles, or molecules
Dalton’s law the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture
Boyle’s Law For a fixed amount of an ideal gas kept at a fixed temperature, P and V are inversely proportional (while one increases, the other decreases)
Charles Law At constant pressure, the volume of a given mass of an ideal gas increases or decreases by the same factor as its temperature (in Kelvin) increases or decreases
Gay-Lussac’s Law The pressure of a fixed mass and fixed volume of a gas is directly proportional to the gas’s temperature
Fick’s Law molecules go from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient
Graham’s Law the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles
Henry’s laws At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid
Laplace’s law The larger the vessel radius, the larger the wall tension required to withstand a given internal fluid pressure.
Pascal’s Principle Pressure is transmitted undiminished in an enclosed static fluid
Stokes’ law shows the force needed to move a small sphere through a continuous, quiescent fluid at a certain velocity
Poiseuille’s law Laminar flow is influenced by viscosity, lenght of tube, flow rate and more importantly Radius.
Bernoulli’s for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid’s potential energy
Venturi The fluid velocity must increase through the constriction to satisfy the equation of continuity, while its pressure must decrease due to conservation of energy: the gain in kinetic energy is supplied by a drop in pressure or a pressure gradient force.
Hooke’s law the extension of a spring is in direct proportion with the load added to it as long as this load does not exceed the elastic limit
Beer’s law if the path length and the molar absorptivity (or the absorption cross section) are known and the absorbance is measured, the concentration of the substance (or the number density of absorbers) can be deduced
Question Answer
Describe Hooke’s law an elastic body will stretch equally for each unit of force (weight) applied, up to the elastic limit, beyond which causes permanent distortion.
Define compliance the ease in which the lungs distend.
The reciprocal of compliance is: elastance
Formula used to calculate lung compliance: change in vol / change in pressure ml/cmH2O
normal compliance: 100 ml/cmH2O
Describe a time constant the time required to fill the lungs to 63% capacity
formula to calculate time constant lung compliance x Raw
Describe LaPlace’s law the inflation pressure is inversely related to the radius and directly related to the surface tension at the air-liquid interface
define surface tension then tension found at the surface of a liquid creasted by the cohesive forces inside the liquid
cohesive attraction between like molecules
How is the premature lung affected by LaPlace’s law? The lungs have minimal surfactant production resulting in high surface tension making it hard to expand them.
Define hydrostatic pressure pressure created by a column of liquid and is depends on the density and height of the liquid.
Define osmotic pressure pressure created by osmosis
Define osmosis movement of a solvent through a semipermeable membrane from an solution of lower concentration to a solution of higher concentration tration
List the 4 pressures that influence the movement of fluid into and out of the capillary. capillary hydrostatic, capillary osmotic pressure, interstitial hydrostatic pressure, interstitial osmotic pressure
define diffusion passive movement of molecules from an area of higher concentration to an area of lower concentration
describe a semipermeable membrane a membrane that only allows solvents to pass through it
Question Answer
Respiration Exchange of gases at the capillary level, primarily O2 & CO2.
External Respiration Occurs in the pulmonary capillaries, between the Alveolar Air and Blood.
Internal Respiration Occurs in the systemis system, between the Blood & Tissues.
Diffusion The movement of gas molecules from an area of higher partial pressure to an area of lower partial pressure.. Gas moves according to their ‘individual’ partial pressures and continues until gas reaches equilibrium.
Boyle’s Law P1V1=P2V2 – Temperature is constant & pressure varies inversly to volume.
Charle’s Law V1/T1=V2/T2 – Pressure is constant & volume changes directly with temperature.
Gay-Lussac’s Law P1/T1=V2/T2 – Volume is constant & temperature changes directly with pressure.
Combined Gas Law P1V1/T1=P2V2/T2 – No constant!
Dalton’s Law of Partial Pressure In a mixture of gases, the total pressure is equal to the sum of the partial pressures of each separate gas.
Increased altitude = Decrease in barometric pressure, in gas density and the partial pressure of the gases. BUT fractional concentrations of gases do NOT change.
Water vapor pressure Must be subtracted from total pressure before calculations are made.
Ideal Alveolar Gas Equation PAO2 = (PB – Ph2o) Fio2 – Paco2 (1.25)
PAO2 = (PB – Ph2o) Fio2 – Paco2 (1.25) Partial pressure of O2 in the alveoli = (barometric pressure – partial pressure  of H2O (47mmHg)) fractional concentration of inspired O2 – partial pressure of arterial CO2 (1.25)
Alveolar capillary membrane Composed of 8 layers. Its thickness is between 0.36 & 2.5 microns.
One micron = 1/25,000 of an inch
Oxygen Norms PvO2 = 40 TORR PAO2 = 100 TORR Pressure gradient = 60 TORR
Carbon Dioxide Norms PVCO2 = 46 TORR PACO2 = 40 TORR Pressure gradient = 6 TORR
O2 & CO2 Diffusion Diffuse until gas pressure in the alveoli and pulmonary capillaries are in equilibrium. Normally occurs in 0.25 sec & transit time for blood in pulmonary capillary system is 0.75 sec.
Diseased Lungs Gases may not reach equilibrium; due to pulmonary consolidation, fibrosis, edema or interstitial edema.
Flick’s Law v (gas flow) = (P1-P2)AD/T – flow inversly related to thickness and directly related to the rest!
v (gas flow) = (P1-P2)AD/T gas flow = (pp 1 – pp 2)(area)(diffusion constant)/thickness
Henry’s Law The amount of gas that dissolves in a liquid at a given temperature is proportional to the partial pressure of the gas.
> partial pressure = the more gas will dissolve
< pt temp = less gas will dissolve
Solubility Coefficient The amount of gas that can be dissolved in 1mL of a liquid at 760 TORR and a specified temperature. Each gas has its OWN!
At 37 degress & 760 TORR Solubility coefficient of: oxygen = 0.0244 mL/torr/H2O carbon dioxide = 0.592 mL/torr/H2O (24x faster that O2)
For every 10% > in O2 above room air = Your PAO2 should go up 50 TORR, i.e. 21% = 100 TORR 30% = 150 TORR 40% = 200 TORR 50% = 250 TORR

Question Answer
Boyles Law? If temperature remains constant, pressure will vary inversely to volume.
Charles’ Law? If pressure remains constant, volume and temperature will vary directly.
Gay-Lussac’s Law? If the volume remains constant, pressure and temperature will vary directly. If you increase the pressure in a system it will tend to get hotter. Also, if you increase the pressure within a closed container, the temperature will increase.
Ideal Gas Law? Incorporates pressure, volume and temperature in a mathematical equation.
Dalton’s Law? In a mixture of different gases, the total pressure is equal to the sum of the partial pressures of all these various gases. Ex. Alveolar Air Equation PAO2= [(PB-PH20)x Fi02]-PaCO2x1.25 Assuming PAO2=PaCO2
Fick’s Law? The rate of gas transfer across a sheet of tissue is directly proportional to the surface area of the tissue & to the difference of the partial pressures of the gas between the two sides of the tissue & is inversely proportional to the thickness of tissue
Henry’s Law? The amount of gas that DISSOLVES ina liquid at a given temperature is proportional to the partial pressure of the gas. The amount of gas that can be dissolved by 1 ml of a given liquid at standard pressure (760 mmHG)is known as the solubility coefficient.
Graham’s Law? The rate of DIFFUSION of a gas through a liquid is 1) directly proportional to the solubility of the gas 2) Inversely proportional to the gram molecular weight. Oxygen is lighter, therefore it moves faster than CO2
Absolute Humidity the actual amount of water vapor in a gas (ml/L)
Relative Humidity the actual amount of water vapor in a gas compared with the amount necessary to cause the gas to be fully saturated (%)
Body Humidity The absolute humidity of inspired gas saturated at body temperature
Humidity deficit The difference (mg/L) between the water vapor content of a gas at BTPS (fully saturated air at normal body temperature and pressure) BTPS=Body Temperature Saturated
Question Answer
Ideal gas law PV= nRT
Boyle’s Law States that press and volume of a gas system vary inversely if the temp and amount of gas in the system are constant: P1V1 = P2V2
Charles’ Law States that the temp and volume of a gas system vary directly if the press and amount of gas in the system are constant: V1/T1 = V2/T2
Gay-Lussac’s Law States that he pressure and temperature of a gas system vary directly if the volume and amount of gas in the system are constant: P1/T1 = P2/T2
Combined Gas Law States that pressure, temperature, and volume of gas are specifically related if the amount of gas remains constant: P1T1/V1 = P2T2/V2
Dalton’s Law of Partial Pressures 1. Ptotal = P1 + P2 + P3… 2. The concentration of a gas is equal to the partial pressure of the gas divided by the barometric pressure. 3. The gases act independently of each other. 4. Humidity does has no effect on Dalton’s Law
Avogadro’s Law States that at equal temperatures and pressure equal volumes of different gases, regardless of their mass, contain equal numbers of molecules.
At STP 1 mole of gas will occupy what volume? 22.4 L
How many particles in 1 mole 6.02 x 10^23
Henry’s Law of Solubility The amount of gas that dissolves in a liquid at a given temperature is directly proportional to the partial pressure of the gas above the surface of the liquid.
Graham’s Law of Diffusion The rate at which gases diffuse is inversely proportional to the square root of gram molecular weight (their densities)
Fick’s Law of Diffusion The greater the area, diffusion constant, and pressure gradient, the more diffusion will occur. (And vice versa). A thicker membrane will decrease diffusion.
Pascal’s Principle Fluids confined in a container will transmit force or pressure uniformly in all directions
Define Pressure defined as a force (F) acting perpendicularly to a surface area (A) or P = F / A
Question Answer
What is STPD and why is it important? Standard Tempeture and Pressure Dry- water vapor occupies space, therefor dry gas has a lower volume than “wet”/saturated volume. It is clinically important when discussing gas pressures in the lung where things are “wet”.
What is the term used to discribe the quantity of water in a particular volume of air thats most common units are shown in grams per cubic meter? Absolute Humidity.
What is absolute zero? A tempeture in which there is no kenetic energy.
Which law predicts how much of a given gas will disolve in liquid? Henry’s Law (V = a X P gas)
Which gas law states, at a consistant tempeture the pressure of a gas inversely proportional to the volume? Boyles Law.P1V1 = P2V2
Which law states, when you change the tempeture of a gas the pressure changes? Gay-Lussac’s Law.P1/T1 = P2/T2
Wich law has no constant factor but has all the same properties as three other laws? The Combined Gas Law.(P1V1)/T1 = (P2V2)/T2
Which law staes the total pressure of a gas mixture must = the sum of the partial pressures of all its parts? Dalton’s Law of Partial Pressure.
What is Buoyancy and what principal does it belong to? Archimedes Principle- pressure below a submerged object is higher than pressure above it (this difference is an upward force).
Define laminar flow. A pattern of flow consisting of concentric layers of fluid flowing parallel to the tube wall at linear velocities that increase towards the center.
Define turbulent flow. The pattern of flow through a tube changes significantly, with a loss of regular streamlines. Fluid molecules form irregular eddy currents in a chaotic pattern.
What are the three primary states of matter? Solids, liquids and gases.
What is flow resistance? The difference between pressures at two points along a tube divided by flow.
The change in pressure required to produce a given flow (under laminar flow conditions) through a smooth tube of a fixed size is which law? Pouseuille’s Law.
What is capillary action and how does it affect the Respiratory therapist? A phenomenon in which a liquid in a small tube upward against gravity. This is important because of blood sampling and some of the absorbent wicks used in some of the gas humidifiers.
What is the dew point? The temperature at which water vapor condenses back to its liquid form.
What is the barometric pressure formula? pressure=height of column X density of liquid
If we have two liters of a gas at a tempeture of 420 K, what will the new volume be? What law will you use to solve the problem? You would use the Combined gas law to find the answer. since pressure was never mentioned, ignore it. The equation is V1/T1 = V2/T2 2L/420 = x /350 answer= 1.67L
What law states the lighter gases diffuse more rapidly and heating or agitation of gases speed up diffusion (based on kenetic energy). Grahams Law.
What does Pascal’s principle tell us? It tells us that a static liquid pressure depends on the depth of the fluid.P = H x density