6 Pressure, Flow, Energy, BP, Vaporization, Heat, & Temp Flashcards
Force
That which changes or tends to change the state of rest or motion of an object Push or pull on an object Vector - direction and magnitude Type of energy = Mass (kg) · Acceleration (m/s^2 ) = (kg · m)/s^2 Newtons (N) (g · cm)/s^2 = Dyne SVR/PVR
Work
Measurement of the amount of change a force produces when it acts on an object/body = Force · Distance (displacement) = (Mass · Acceleration) · Distance = kg · (m/s^2 ) · m = Newton · meters = (kg 〖· m〗^2 )/s^2 = 1 Joule (J)
Total Energy
Kinetic + Potential energy Internal energy of system = sum potential and kinetic energy in the particles w/in the system Energy - the currency of force Capacity to do work (measured in ft lbs) Measured in Joules
Kinetic Energy
= (Mass ·(Velocity)^2 )/2 OR Mass · (Velocity)^2 · 0.5
Energy of motion - energy a mass possesses by being in motion
Measured in Joules
Potential Energy
= Mass · 9.8 m/s^2 · Height = kg · 9.8 m/s^2 · m = (kg ·〖 m〗^2 )/s^2 = Joule Energy of height (gravity impact) *stored for later use* Example: Rollercoaster Measured in Joules
Power
= Work/Time
= Joules/Seconds
= Watts
Reynolds Number
Predicts laminar or turbulent flow (Inertial Forces)/(Cohesive Forces) Re < 2,000 Laminar Flow Re > 4,000 Turbulent Flow (↑ Resistance) Re 2,000−4,000 Transitional Re = (velocity ⋅ diameter ⋅ density)/viscosity Does not consider or predict resistance
Resistance/Flow/Pressure
Q = ∆P/R
∆P = Q x R
R = ∆P/Q
Flow - volume gas or liquid passing through cross-sectional area over unit of time (length/seconds) produced by pressure gradient application
Pressure
= Force/Area ↑ surface area ↓ pressure ↓ area ↑ pressure Density directly proportional ↑ density ↑ pressure Administering drug via 18G vs. 24G IV
Dalton’s Law
Partial pressure - exerted by single gas component of mixture
P1 + P2 + P3 + PN = Total pressure
Atmospheric Pressure Units
760mmHg 760 Torr 14.7 PSI 1,000cmH2O 100 kPa 1 bar 33 ftH2O
Pressure at Altitude
Sea level = 1 Atmosphere 10,000ft = 0.66 (2/3) 1 Atmos 20,000 = 0.5 (1/2) 1 Atmos NOT linear relationship b/w altitude & pressure 60,000 H2O boils 37°C Underwater: 33ft H2O = 2 Atmos 66ft H2O = 3 Atmos 99ft H2O = 4 Atmos H2O much more dense than air
Acceleration
m/s^2
s^2 = traveling at specific rate m/s per second
Rate
m/s
Cruise control - constant mph
Pascal’s Law
External pressure transmitter equally throughout = homogenous
Pressure transmitted equally therefore able to read via gauge to measure pressure w/in
Not affected by gravity
Atmospheric Gas Composition & Pressure
Dry air N2 79% 594mmHg O2 21% 159mmHg (1% trace inert gases) Water vapor 47mmHg
PSIG
Pounds per square inch gauge
Set to read 1 atm (14.7psi or 760mmHg) less than absolute pressure
Indicates usable/useful volume of gas in container
Tank works via negative pressure system, once equilibrates w/ atmosphere then gas will no longer be able to flow out
“Empty” tank not truly empty
PSIA
Absolute pounds per square inch
Set to read the TOTAL about gas present in container
Cannot get out unless suction out remainder
Absolute Pressure
Gauge pressure + Atmospheric pressure
Total amount gas present in the container
Laminar Flow
Stronger intermolecular and cohesive forces = more likely to have laminar flow
↑ IMF ↑ viscosity
VISCOSITY keeps molecules “in-line”
“Sheets” of molecules
Flow α 1/Viscosity
↑ viscosity ↓ flow
Viscosity determinant of gas flow when flow is laminar
Turbulent Flow
Velocity, diameter, & density - forces that tend to disrupt cohesive forces therefore molecules move “out of line”
Flow α 1/√Density
↑ density ↓ flow
Density determinant of gas flow when flow is turbulent
Influences probability that interactions b/w fluid molecules will occur - ↑ density ↑ molecules per unit area ↑ chance of molecular collisions ↑ drag ↑ resistance ↓ flow
Boiling Point
Temperature at which the vapor pressure of liquid equals ambient pressure
Entirety of liquid enters the gas phase
↑ ambient pressure ↑ BP
Ex: Desflurane ↑ temperature
Vaporization
Conversion of volatile liquid to a vapor/gas
Aided by heat
Heat
Total kinetic energy of molecules of a substance
Heat energy flows from increased heat to area w/ lower heat energy (hotter to cooler substance) = heat exchange
Energy in form of kinetic energy - resides w/in molecules of the substance
Thermal gradient or conductance
Measurement of substance’s ability to conduct (exchange) heat = thermal conductivity
Temperature
Thermal state of substance which determines whether it will give heat to another substance or receive heat from another
Average kinetic energy of the molecules of a substance
1L 80°C vs. 3L 80°C water bottle - same temperature
3L will give off more heat
Take 0.5L from each = equal temp and heat
Endothermic Process
State of matter change that requires heat input
Chemical example: A + B + Heat = C
Physical change: Ice → Water (add heat)
Exothermic Process
State of matter change that required output of heat energy or energy flow out of the system Giving off heat (output) Steam → water → ice Gas → liquid → solid Heat liberated/released
Conduction
Heat transferred from one point to another by direct contact
Patient placed on cold surface
Convection
30%
Heat transfer that occurs when a fluid flows over a solid while temperature between the fluid and solid are different
Convection oven or fan blowing cool air
Radiation
40%
Transfer of heat through divergence in all directions from a center
Body heat radiates to other objects in the room
Evaporation
Heat transfer through converting liquid to a vapor
Sweat, wet blankets, or humidification of dry inspired gas
Kelvin
0°C = 273°K
°K = °C + 273°
Absolute zero = 0
Fahrenheit
°F = (C° · (9/5)) + 32
Absolute zero = -459.7
Celsius
°C = (°F − 32) · (5/9)
Absolute zero = -273
Anion Gap
Na – (Cl + HCO3)
Strong Ion Difference
(Strong cations) – (strong anions)
(Na+) + (K+) + (Ca2+) + (Mg2+)) - (Cl- + Lactate
Henderson-Hasselbalch
pH = 6.1 + log (HCO3¯/PaCO2 x 0.03)
H2O Vapor Pressure
Room Temp 20°C = 17.5mmHg
37°C = 47mmHg
Boiling Point 100°C = 760mmHg
Water vapor present in body - lungs, alveoli, etc.
Graham’s Law
Density = gas molecular weight
Relates flow through an orifice (turbulent) to gas density
Flow α 1/√Density
Gas flow rate = 1/√MW
Poiseuille’s Law
Relates volume of flow through a tube (laminar) to diameter, pressure differential, length, and viscosity
Tube - pathway where length > diameter
Flow α 1/Viscosity
Volume of flow = ∆P/R
Flow proportional to change in pressure/viscosity
Atmospheric Pressure
Pressure exerted by the weight of the atmosphere that varies w/ altitude
Airplane cabin pressurized at 30,000ft to prevent hypoxia d/t low air pressure at high altitudes
Ambient Pressure
Refers to pressure of the medium in which a specific object is located; environment in at any given moment
Ex: Hyperbaric chamber, or diving underwater
Variable Orifice Tube
Flowmeter increased diameter as flow increases to decrease resistance
Pressure remains constant despite ↑ flow
P = Q x R
↑ flow ↓ resistance (↑ diameter)
More turbulent flow as diameter increases (float bounces more than at low flow rates when laminar flow present)
Dew Point
Temperature at which (if volume of air cooled) moisture precipitates out
Measure of humidity in the air
Air more loaded w/ water vapor more likely for water to condense out
Higher dew point = more moisture in the air (saturated)
Increased temp when water condenses - condensation
Bernoulli’s Theorem
↓ diameter ↑ velocity Constant flow TE1 = TE2 KE1 +PE1 = KE2 + PE2 Therefore ↑KE ↓PE Result ↓ pressure energy
Venturi Effect
Constriction allows second gas to be drawn inward (suction) and mixed w/ the first gas therefore diluting
Venturi masks - port open to room air
↓ diameter ↑ suction ↑ dilution ↓ O2 concentration
40% O2 ↑ diameter
24% O2 ↓ diameter (narrower opening)
Pressure Relief Valve
Spring exerts particular force on disc w/ particular surface area - valve requires particular pressure w/in to open
Pressure in tube > valve pressure
Valve pushed upward revealing vents through which pressure can dissipate
Spring pressure (stiffness) can be adjusted to calculate pressure required to open the valve
“Pop-off” valve
Ambu bag
Pressure Reducing Valve
High pressure enters the valve pushing upward against the diaphragm downward force produced by the spring (resistance)
Pressure energy required to do work moving the diaphragm therefore lower pressure exits gas outlet
Work + energy required
Ex: Oxygen tank
Force/Energy/Work Relationship
Pushing an object in a certain direction involves applying a force, which does work, and energy must be expended
Force - influence that causes a change in the motion of an object aka acceleration; method to transfer energy
Work - exertion of force to produce movement
Energy - expended when work is done (to apply force some amount of energy is required; energy transferred to object)
Energy Definition
Capacity to do work
Quantified as the amount of work done per unit of time
Work = Force acting over a distance
Newton/Dyne/Joules
Force that will accelerate mass of 1 kg, 1 meter/sec^2
Gravity force accelerates any object 9.81 m/sec^2
Therefore force of gravity on 1 kg mass = 9.81 N
Dyne = (g · cm)/s^2
Smaller force measurement - SVR/PVR
Joules - unit of energy or work
Work done by force of 1 N moving an object 1 meter
Gas Composition
21% O2
78% N2
1% Trace
Vapor Pressure
Pressure exerted by vapor particles in equilibrium w/ associated liquid - few receptors jumping into constitutive state, liquid molecules vaporize but liquid not boiling
↑ particles in gas state ↑ VP
Saturated VP - same number molecules return to the liquid as escape from it; atmosphere above the liquid = saturated
When VP = P Atm = BP
NOT affected by atmospheric pressure
↑ polarity or mass ↓ VP
↑ temp ↑ VP (H2O @ 37° 47mmHg vs. 100° 760mmHg)
↑ INTERmolecular forces ↓ VP
Resistance
Passive force exerted in opposition to another and active force
↑ resistance ↑ pressure DROP
Factors r/t resistance:
Friction - produces resistance to flow in tube; caused by adhesive and cohesive forces
Viscosity - measure of fluids’ internal resistance (cohesive force) to flow; increases w/ increasing IMFs
Absolute Zero
No movement of H2O particles
°F = -459.7°
°C = -273°
°K = 0°
