Fluids and Gas Laws Vocabulary Review

A comprehensive set of 150 vocabulary flashcards covering fluid dynamics, gas laws, and their clinical applications in anesthesia and respiratory care.

Daniel Bernoulli

A Swiss mathematician and physicist born 8th February 1700, best known for Bernoulli's Principle.

Bernoulli's Principle

The principle stating that an increase in the velocity of a fluid occurs concurrently with a decrease in internal fluid pressure.

Dalton's Law of Partial Pressure

The law stating that the total pressure of a mixture of gases is the sum of the partial pressures of each individual gas.

Dalton's Law Formula

$$P_{total} = P_1 + P_2 + P_3 + \dots$$

Law of Conservation of Energy (Fluids)

Energy per unit volume before equals energy per unit volume after, expressed as $P + \frac{1}{2}\rho v^2 + \rho gh = \text{constant}$.

Henry's Law

The law relating gas solubility to pressure, expressed as $S_g = k P_g$.

Boyle's Law

The gas law stating that pressure and volume are inversely proportional when temperature and amount are constant ($PV = K$).

Gay-Lussac's Law

The gas law stating that pressure is directly proportional to temperature when volume and amount are constant ($P = KT$).

Charles's Law

The gas law stating that volume is directly proportional to temperature when pressure and amount are constant ($V = KT$).

Universal Gas Constant ($R$)

A constant used in the ideal gas law, identified in the notes as $8.314\,erg\,mol\,k$.

Ideal Gas Law

The equation relating pressure, volume, amount of gas, and temperature: $PV = nRT$.

Fluid

A material, specifically gases and liquids, that can flow and continuously deform under shear force.

Hydrostatics

The study of fluids that are resting or not moving.

Hydrodynamics

The study of fluids in motion.

Hydromechanics

The mechanics of fluids, encompassing both hydrostatics and hydrodynamics.

Dynamic Lung Compliance

The compliance of the lung at any given time during the actual movement of air.

Static Lung Compliance

Pulmonary compliance measured during periods without gas flow, such as an inspiratory pause.

Pressure ($P$)

Defined as the force applied per unit area ($P = F/A$).

Static Fluid Pressure Formula

$P_{\text{static fluid}} = \rho gh$, where $\rho$ is density, $g$ is gravity, and $h$ is depth.

Standard Acceleration of Gravity ($g$)

The constant value used for gravity calculations, given as $9.8\,m/s^2$.

Density ($\rho$)

The mass per unit volume of a substance ($\rho = m/V$).

Pascal Vases

A set of connected containers used to illustrate that water pressure depends on depth and not on the volume or shape of the container.

Total Pressure (Submerged Object)

The sum of the pressure the liquid exerts plus the atmospheric pressure ($P_0$).

Atmospheric Pressure Value

Approximately $1\,atm$ or $1.013 \times 10^5\,Pa$, equivalent to $14.7\,psi$.

Pascal's Principle

The statement that a change in pressure in a confined fluid is transmitted without change to all points in the fluid and to the walls of the container.

Hydraulic Lift

An application of Pascal's Principle using an incompressible fluid to transmit pressure from a small cylinder to a larger one.

Heimlich Maneuver (Fluid Physics)

A clinical application of Pascal's Principle where a sharp pressure increase in the abdomen is transmitted to the throat.

Compression Therapy

The application of pressure to limbs using a wrap, transmitting pressure to muscle and blood to aid venous return to the heart.

Buoyancy

The power of a fluid to exert an upward force on a body placed in it, arising from pressure differences between the top and bottom of the object.

Archimedes' Principle

The principle stating that the upward buoyant force on a body is equal to the weight of the fluid that the body displaces.

Hydrometer

An instrument for measuring the specific gravity of liquids, consisting of a weighted glass tube that floats upright.

Specific Gravity

The ratio of the density of a substance to the density of a reference substance (usually pure water at $1.0$).

Newtonian Fluid

A fluid whose viscosity remains constant regardless of the amount of shear applied at a constant temperature.

Non-Newtonian Fluid

A fluid whose viscosity changes (increases or decreases) when shear stress is applied.

Viscosity ($\eta$ or $\mu$)

A measure of a fluid's resistance to flow or deformation at a given rate, often described as 'friction between molecules.'

Absolute Viscosity

Also known as dynamic viscosity, it measures the force required to move one fluid layer against another.

Newton's Law of Viscosity

States that for a given temperature and pressure, a Newtonian fluid will flow with a constant viscosity regardless of external force.

Reynolds Number ($Re$)

A dimensionless quantity used to predict whether fluid flow will be laminar, transitional, or turbulent.

Inertial Forces

Forces arising from a fluid's tendency to resist changes in motion.

Viscous Forces

Forces stemming from a fluid's internal friction.

Laminar Flow (Reynolds Range)

Flow occurring when the Reynolds number is less than $2,000$ ($Re < 2,000$).

Transitional Flow (Reynolds Range)

Flow occurring when the Reynolds number is between $2,000$ and $4,000$. ($Re = 2,000 \text{ to } 4,000$).

Turbulent Flow (Reynolds Range)

Flow occurring when the Reynolds number is greater than $4,000$ ($Re > 4,000$).

Laminar Flow Characteristics

Molecules travel in a parallel pattern with the fastest velocity in the center and zero velocity at the walls.

Transitional Flow Pattern

A flow type displaying a turbulent pattern in the center and a laminar pattern near the walls of the tube.

Turbulent Flow Characteristics

Molecules travel in a chaotic pattern, forming eddies.

Critical Velocity

The specific velocity at which flow changes from laminar to turbulent.

Laminar Flow Example (Clinical)

The airflow in the terminal bronchioles or blood flow in systemic circulation.

Turbulent Flow Causes

High flow rates, orifices, sharp angles ($> 25\,degrees$), or branching tubes.

Status Asthmaticus (Flow Physics)

A condition causing increased airway resistance, leading to increased flow turbulence and work of breathing (WOB).

Heliox

An oxygen/helium mixture used to decrease Reynolds' number and improve airflow by reducing density when airway resistance is high.

Graham's Law

States that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its density or molar mass ($rate \propto \frac{1}{\sqrt{M}}$).

Thorpe Tube

A constant-pressure variable orifice flow meter used in anesthesia, where the diameter is smallest at the bottom.

Flow Meter Calibration

These devices are gas-specific because flow depends on viscosity (low flows) or density (high flows).

Annular Space

The space between a bobbin/float and the tube wall in a flow meter, which simulates an orifice at high flow rates.

Volumetric Flow Rate ($Q$)

The volume of fluid passing a particular point per unit time, measured in $m^3/s$.

Velocity-Diameter Relationship

As the diameter of a tube decreases, the velocity of the fluid increases to maintain a constant flow rate.

Bernoulli Equation Restrictions

Valid only when flow is steady, density is constant (incompressible), and friction losses are negligible.

Kinetic Energy per Unit Volume

Expressed in the Bernoulli equation as $\frac{1}{2}\rho v^2$.

Potential Energy per Unit Volume

Expressed in the Bernoulli equation as $\rho gh$.

Shower Curtain Effect

The movement of a curtain inward caused by the decrease in air pressure resulting from the high velocity of gushing water.

Bernoulli Effect Application (Aircraft)

The generation of lift for airplane wings due to pressure differences between the top and bottom surfaces.

Venturi Effect

An application of Bernoulli's principle where pressure drops at a point of constriction, potentially creating a vacuum that entrains air.

Air Entrainment

The process of pulling surrounding room air into a tube due to a pressure drop below atmospheric pressure.

Venturi Flowmeter

A device that uses the pressure drop at a tube constriction to measure fluid flow.

Coanda Effect

The tendency of a fluid jet to attach itself to a nearby curved surface and follow the curve rather than traveling in a straight line.

Mitral Regurgitation (Coanda Effect)

A 'wall-hugging' jet where blood flow follows the shape of the left atrial wall.

Low Frequency Jet Ventilation (LFJV)

A system using a high-pressure oxygen injector and the Venturi effect to entrain air and provide tidal volumes.

Venturi Mask

A medical device designed to deliver a precise oxygen concentration ($FiO_2$) by utilizing air entrainment.

Moran Campbell

The inventor of the Venturi mask at McMaster University Medical School.

FiO2 (Venturi Mask)

Fraction of Inspired Oxygen, determined by the size of the internal jet nozzle and the size of the entrainment windows.

Small Jet Orifice (Venturi Mask)

Component that increases oxygen velocity significantly, resulting in higher room air entrainment and lower $FiO_2$.

Large Entrainment Ports (Venturi Mask)

Openings that allow more room air to mix with pure oxygen, resulting in a lower $FiO_2$ but higher total gas flow.

Hypoxic Drive

The biological drive to breathe that is managed in COPD patients using the precise $FiO_2$ of a Venturi mask.

Pethick's Test

A clinical test used to check the integrity of the inner tube of an anesthesia circuit.

Sander's Jet Injector

A device connected to a bronchoscope that utilizes the Bernoulli principle for ventilation.

Hemodynamics

The principles governing blood flow in the cardiovascular system, involving flow, pressure, resistance, and capacitance.

Poiseuille's Law (Hagen-Poiseuille Equation)

Describes the flow rate of an incompressible, laminar flow fluid through a narrow tube ($Q = \frac{\pi R^4 \Delta P}{8 \eta L}$).

Flow Resistance Formula (Laminar)

$R = \frac{8 \eta L}{\pi r^4}$.

Ohm's Law Adaptation (Hemodynamics)

$Flow = \frac{\text{Pressure Gradient}}{\text{Resistance}}$ or $Q = \Delta P / R$.

Mean Arterial Pressure (MAP) Formula

$MAP = CO \times TPR$, where $CO$ is Cardiac Output and $TPR$ is Total Peripheral Resistance.

Poiseuille's Law: Radius Significance

Flow rate is directly proportional to the fourth power of the radius ($r^4$), making radius the most dramatic factor affecting flow.

Radius Doubling Effect

Doubling the radius of a tube increases the flow rate by $16$ times ($2^4 = 16$).

Radius Tripling Effect

Tripling the radius of a tube increases the flow rate by $81$ times ($3^4 = 81$).

Radius Halving Effect

Halving the radius of a tube decreases the flow rate to $1/16$th of its original value.

Viscosity Influence on Flow

Flow rate is inversely proportional to viscosity ($\eta$); as viscosity increases, flow rate decreases.

Hydrostatic Pressure Gradient (IV Administration)

The pressure increased by raising the height of an IV pole to increase fluid flow.

Tube Length Influence on Flow

Flow rate is inversely proportional to the length of the tube; longer tubes result in less flow rate.

Clinical Application: PRBC Administration

To deliver blood faster, one can increase the radius (large-bore IV), increase the pressure (pressure bag), or decrease viscosity (normal saline dilution).

Polycythemia Flow Effect

A condition that reduces microvascular flow due to increased blood viscosity.

19% Radius Increase Result

A percentage increase in radius that approximately doubles the volume flow rate.

16% Radius Decrease Result

Vasoconstriction by $16\%$ will cut the blood flow in half.

STP (Standard Temperature and Pressure)

Standard conditions defined as $273.15\,K$ and $1.00\,atm$ ($760\,mmHg$).

Standard Molar Volume

The volume of one mole of an ideal gas at STP, which is $22.4\,L$.

Boyle's Law clinical: Ambu Bag

Squeezing the bag increases pressure and decreases volume, delivering air to the patient.

Body Plethysmography

A clinical method used to measure Functional Residual Capacity (FRC) utilizing Boyle's Law.

Charles's Law Clinical: LMA

The inflatable cuff of a laryngeal mask airway expands when placed in an autoclave due to heating.

Charles's Law Clinical: Tidal Breath

A breath of $500\,ml$ at room temperature expands to $530\,ml$ when warmed to body temperature.

Gay-Lussac's Law Clinical: Autoclave

Uses high temperature to increase the pressure of steam for sterilization.

Gas Cylinder Temperature warning

A clinical concern where full cylinders moved from cold climates ($0\,^{\circ}C$) to warm ORs ($20\,^{\circ}C$) experience increased internal pressure.