What does the respiratory system work to do?
Ensure that all tissues receive the oxygen that they need, and can dispose of the CO2 they produce
What does blood do?
In relation to gas exchange
Carries gases to and from tissues, where the lungs exchange them with the atmosphere
What is the Kinetic Theory of Gases?
Gases are a collection of molecules moving around a space, generating pressure by colliding with the walls of the space. As collisions become more frequent, and harder, the pressure goes up.
What is Boyle's Law?
If a given amount of gas is compressed into a smaller volume, the molecules will hit the wall more often, therefore pressure will rise.
If temperature is constant, pressure is inversely proportional to volume
What is Charles' Law?
The kinetic energy of molecules increases with temperature. As temperature increases, the molecules hit the walls more often, so pressure increases.
Pressure is proportional to absoloute temperature (scale starts at absoloute zero)
What is the Universal Gas Law?
Pressure x Volume = Gas constant x Temperature (oK)
What does the Universal Gas Law allow?
The calculation of how volume will change as pressure and temperature changes
What is meant by partial pressure?
In a mixture of gases, molecules of each type behave independently, so each gas exerts its own pressure, which is a portion of the total pressure- a partial pressure
What is partial pressure calculated as?
The same fraction of the total pressure as the volume fraction of the gas in the mixture
What is meant by vapour pressure?
In biological systems, gas mixtures are always in contact with water, so gas molecules dissolve, and water molecules evaporate, and then exert their own partial pressure- this is known as vapour pressure
What is meant by saturated vapour pressure?
When the rate of molecules entering and leaving water at the same time is equal, this is the saturated volume pressure
How much water vapour is in gases when they enter our body?
In terms of saturation
They are completely saturated with water vapour
Why are gases entering our body completely saturated with water vapour?
So they don't dry out our lungs
What does gas tension in liquids indicate?
How readily a gas will leave the liquid, not (at least directly) how much gas is in the liquid
What is tension equal to at equilibrium?
How quickly is tension equilibrium reaching in the body?
What is the amount of gas that enters a liquid to establish a particular tension determined by?
How is content of gas in a liquid calculated?
Content = solubility x tension
i.e. how easily a gas will dissolve x how readily it will leave
What must happen if the gas reacts with a component of the liquid?
With regards to tension and content
The reaction must be complete before tension, and therefore content can be established
What is total content equal to?
Total content = Reacted gas + Dissolved gas
What is meant by tidal volume?
The lung volume that represents the amount of air that is displaced between normal inspiration an expiration, when extra effort is not required
Draw a diagram illustrating-
- Inspiratory capacity
- Expiratory reserve volume
- Residual volume
- Vital capacity
- Inspiratory reserve volume
- Tidal volume
- Funtional residual capacity
- Total lung capacity
What is meant by respiratory rate/pulmonary ventilation rate?
The number of breaths taken in a set time, usually 60 seconds
What are the two circulations of the lungs?
What is the bronchial circulation part of?
The systemic circulation
What is the purpose of the bronchial circulation?
It meets the metabolic requirements of the lungs
What is the pulmonary circulation?
The blood supply to the alveoli
What is the pulmonary circulation required for?
What must the pulmonary circulation accept?
The entire cardiac output
At what resistance does the pulmonary circulation work?