CGIER 29 - Gas Laws: clinical relevance, gas pressure Flashcards
Boyle’s law
For a fixed mass of enclosed gas at constant temperature, the product of the pressure (P) and volume (V) remains constant
Charles law
For a fixed mass of enclosed gas at constant pressure the ratio of Volume to Temperature is constant
Charle’s law formula
V/T = constant
Boyle’s law formula
P1V1 = P2V2
Combination of Boyle’s and Charle’s law combined to make…
Ideal Gas Law
Ideal Gas Law formula
P1V1/T1 = P2V2/T2
must be expressed in Kelvin
PV =
PV = nRT
Consequences of Ideal Gas Law
reduction in Temp can produce a corresponding decrease in. pressure
refrigeration process
slowly compress a closed volume of refrigerant gas and then rapidly removing the pressure (decompressing) which cools the gas.
how does de-compression cause the formation of the cloud
Smoke particles act as condens-ation nuclei for clouds to form about
how is charles law applicable to engines in diesel vehicles
compressed - high pressure - high temperature - spontaneous ignition in engine
gauge pressure effect
pressure varies with height
partial pressure of a gas in a gas mixture
the pressure an individual gas would exert if it, alone, occupied the volume.c
Daltons law
states that the total pressure of a mixture of gases = the sum of partial pressures exerted by the gases if they were present separately
Henry’s Law
the concentration or solubility of a gas in a liquid is proportional to the partial pressure of that gas above the surface
what determines the solubility of a gas in a liquid/tissue? Name an example
partial pressure determines the solubility of a gas in a liquid or tissue
fizzy drinks
laplace’s law
Relates the tension in a membrane to the pressure difference on either side
laplace’s law formula
pressure difference = 2(Wall Tension) / RadiusT increases and R increases
application of laplace’s law formula
vacuum outside balloon - evacuate vacuum - decrease of pressure in vacuum outside of balloon -
balloon swells up
exceed plastic limit and rupture the membrane
alveolus diameter
0.2mm
thickness of wall of alveolus
4x10-6
why is alveoli surface area up 80m2^
oxygen transport occurs in passive diffusion
cannot be forced
in order to maximise gas transport we must increase surface area
describe inspiration (inhaling)
During inspiration, diaphragm moves down, intercostal muscles move out.
The Pleural Volume increases, causing the Pleural Pressure (Po in Laplace) to decrease
describe pressure in alveloi as one inhales
As alveolus expands it creates a temporary low pressure area inside alveolus. Atmosphere rushes in.
Describe expiration
During expiration, diaphragm and intercostals relax. Pleural Volume decreases. Pleural Pressure (Po in Laplace) rises
Describe pressure in alveoli as one exhales
As alveolus constricts it creates a temporary high pressure area in side alveolus. Breath is pushed out, passively
describe state of airways during asthma or croup
A small reduction in airway diameter can result in extreme difficulty in breathing.
Gases partially obey poiseulle’s law
