CGIER 29 - Gas Laws: clinical relevance, gas pressure

Question 1

Boyle’s law

Answer 1

For a fixed mass of enclosed gas at constant temperature, the product of the pressure (P) and volume (V) remains constant

Question 2

Charles law

Answer 2

For a fixed mass of enclosed gas at constant pressure the ratio of Volume to Temperature is constant

Question 3

Charle’s law formula

Answer 3

V/T = constant

Question 4

Boyle’s law formula

Answer 4

P1V1 = P2V2

Question 5

Combination of Boyle’s and Charle’s law combined to make…

Answer 5

Ideal Gas Law

Question 6

Ideal Gas Law formula

Answer 6

P1V1/T1 = P2V2/T2

must be expressed in Kelvin

Question 7

PV =

Answer 7

PV = nRT

Question 8

Consequences of Ideal Gas Law

Answer 8

reduction in Temp can produce a corresponding decrease in. pressure

Question 9

refrigeration process

Answer 9

slowly compress a closed volume of refrigerant gas and then rapidly removing the pressure (decompressing) which cools the gas.

Question 10

how does de-compression cause the formation of the cloud

Answer 10

Smoke particles act as condens-ation nuclei for clouds to form about

Question 11

how is charles law applicable to engines in diesel vehicles

Answer 11

compressed - high pressure - high temperature - spontaneous ignition in engine

Question 12

gauge pressure effect

Answer 12

pressure varies with height

Question 13

partial pressure of a gas in a gas mixture

Answer 13

the pressure an individual gas would exert if it, alone, occupied the volume.c

Question 14

Daltons law

Answer 14

states that the total pressure of a mixture of gases = the sum of partial pressures exerted by the gases if they were present separately

Question 15

Henry’s Law

Answer 15

the concentration or solubility of a gas in a liquid is proportional to the partial pressure of that gas above the surface

Question 16

what determines the solubility of a gas in a liquid/tissue? Name an example

Answer 16

partial pressure determines the solubility of a gas in a liquid or tissue
fizzy drinks

Question 17

laplace’s law

Answer 17

Relates the tension in a membrane to the pressure difference on either side

Question 18

laplace’s law formula

Answer 18

pressure difference = 2(Wall Tension) / RadiusT increases and R increases

Question 19

application of laplace’s law formula

Answer 19

vacuum outside balloon - evacuate vacuum - decrease of pressure in vacuum outside of balloon -
balloon swells up
exceed plastic limit and rupture the membrane

Question 20

alveolus diameter

Answer 20

0.2mm

Question 21

thickness of wall of alveolus

Answer 21

4x10-6

Question 22

why is alveoli surface area up 80m2^

Answer 22

oxygen transport occurs in passive diffusion
cannot be forced
in order to maximise gas transport we must increase surface area

Question 23

describe inspiration (inhaling)

Answer 23

During inspiration, diaphragm moves down, intercostal muscles move out.
The Pleural Volume increases, causing the Pleural Pressure (Po in Laplace) to decrease

Question 24

describe pressure in alveloi as one inhales

Answer 24

As alveolus expands it creates a temporary low pressure area inside alveolus. Atmosphere rushes in.

Question 25

Describe expiration

Answer 25

During expiration, diaphragm and intercostals relax.
Pleural Volume decreases.
Pleural Pressure (Po in Laplace) rises

Question 26

Describe pressure in alveoli as one exhales

Answer 26

As alveolus constricts it creates a temporary high pressure area in side alveolus. Breath is pushed out, passively

Question 27

describe state of airways during asthma or croup

Answer 27

A small reduction in airway diameter can result in extreme difficulty in breathing.
Gases partially obey poiseulle’s law