Week 1 - Overview And Gas Laws Flashcards
Why do we need a respiratory system?
To supply body with oxygen for aerobic metabolism
To dispose of CO2 produced by metabolism
What is Boyle’s law?
Pressure of a gas is inversely proportional to its volume
What divisions are in the conducting airways?
1-16 (no gas exchange)
What divisions are in the respiratory zone of the airways?
17-23 (gas exchange takes place)
What is partial pressure?
The measure of concentration of a gas
What is the PO2 in alveolar air and capillary blood?
13.3 KPa
What is the PO2 in pulmonary capillaries and interstitial fluid?
6 KPa
What is Dalton’s las of partial pressures?
Each gas in a mixture exerts a partial pressure equal to the pressure it would exert if it was the only gas present
How is partial pressure related to a gases percentage of a mixture?
It is directly proportional e.g. In a mixture at 100 KPa, a gas that occupies 20% would contribute a pressure of 20 KPa
What happens when inspired gases come into contact with body fluids?
Water molecules evaporate to enter gas phase until gas mixture is saturated
Gas molecules enter water to dissolve in liquid
What is the saturated vapour pressure?
The pressure water vapour exerts, 6.28 KPa at body temperature
What is Henry’s law?
The amount of gas dissolved is proportional to the pressure of the gas in contact with the liquid
What is the equation for the amount of oxygen dissolved in plasma?
Amount dissolved=solubility coefficient of O2 x PO2
How does the partial pressure in alveolar air differ from the partial pressure in atmospheric air?
Has added water vapour
02 constantly leaving and CO2 constantly entering therefore a lower percentage of O2 and a higher percentage of CO2
What is the PCO2 of capillary blood?
5.3 KPa
