1. Histology of the Respiratory System Flashcards
(120 cards)
What are the broad functions of the respiratory system?
To ensure all tissues receive the oxygen that they need and can dispose of the carbon dioxide they produce.
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, 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 the 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 absolute temperature.
What is the universal gas law?
It allows the calculation of how the volume will change as pressure and temperature changes. Pressure x volume = gas constant x temperature (K).
What is 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.
How is partial pressure calculated?
As a fraction of the total pressure as the volume fraction of the gas in the mixture.
What is vapour pressure?
In biological systems, gas mixtures are always in contact with water. So gas molecules dissove, and water molecules evaporate, and then exert their own partial pressure. This partial pressure is the vapour pressure.
What is the saturated vapour pressure?
When the rate of molecules entering and leaving water at the same time is equal, this is the saturated vapour pressure. When gases enter our body, they are completely saturated with water vapour.
Why do gases in the body have to be saturated with water?
So they don’t dry out the lungs.
What is gas tension?
Gas tension in liquids indicate how readily the gas will leave the liquid. At equilibrium, tension = partial pressure.
What is the content of gas in a liquid?
The amount of gas that enters a liquid to establish a particular tension that is determined by solubility.
What does the content of gas in a liquid depend on?
It’s solubility, content = solubility x tension.
How can the content of gas in a liquid be calculated when the gas reacts with a component of the liquid?
The reaction must firstly be complete. Total content = reacted gas + dissolved gas.
What is the total oxygen gas content in blood?
8.93 mmol/L.
How is the oxygen content in blood calculated? (Include values).
Total = oxygen bound to haemoglobin + oxygen dissolved in plasma = 8.8 + 0.13 = 8.93 mmol/L.
What is the tidal volume of the lung?
The lung volume that represents the amount of air that is displaced between normal inspiration and expiration, when extra effort is not applied.
What is 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?
Pulmonary and bronchial.
What is the bronchial circulation part of?
The systemic circulation.
What is the function of the bronchial circulation?
Meets the metabolic needs of the lungs.
What is the function of the pulmonary circulation?
Blood supply to the alveoli for gas exchange.
How can the pulmonary circulation work at a low pressure whilst still accepting the entire cardiac output?
It has short, wide vessels, lots of capillaries that are joined in parallel and arterioles with relatively little smooth muscle.
Why do ventilation and perfusion of alveoli need to be matched?
For efficient oxygenation.