VENTILATION Flashcards
What is ventilation?
The movement of air into and out of the lungs
What is tidal volume?
The volume of air taken in and out of each breath
What is respiratory rate?
The number of breaths per minute
What’s the difference between pulmonary and alveolar ventilation?
Pulmonary ventilation is the movement of gas into and out of the lungs whilst alveolar ventilation is the volume of air that participates in gas exchange
How do spirometers work?
It measures the amount of air you can breathe out in one second and the total volume of air you can exhale in one forced breath. These measurements will be compared with a normal result for someone of your age, height and sex, which will help show if your lungs aren’t working properly.
How can residual volume and functional residual capacity be measured?
By the helium dilation method or plethysmography
What is the normal FEV1/FVC?
70%
What is the inspiration reserve volume?
The extra volume of air that can be inspired with maximal effort
What is the inspiration capacity?
The maximum volume of air that can be inspired
What is the expiratory reserve volume?
The extra volume of air that can expired from the lungs after normal expiration
What is the residual volume?
The volume of air remaining in the lungs after maximum, forceful expiration
Why is residual volume so important?
It functions to keep the alveoli open after maximum expiration
What is vital capacity?
The greatest volume of air that can be expelled from the lungs after taking the deepest possible breath
What is the total lung capacity?
The volume of air in the lungs after maximum effort of inspiration
What is the functional residual capacity?
The air remaining in the lungs after normal, passive exhalation
What factors affect the rate of diffusion from alveoli to blood?
Solubility of gases in liquid
Partial pressure of gas
Area available for gas exchange
Thickness of alveolar membrane
What is the diffusing capacity?
a measurement of the rate of transfer of gas from the alveolus to hemoglobin within a capillary
How do you work out the oxygen content?
arterial oxygen tension (PaO2) times the solubility coefficient of oxygen
Describe the structure of haemoglobin?
4 protein globin chains (2 alpha and 2 beta) which associate together in a quaternary structure. Each chain has a haem group which can bind to oxygen. Each haem group has a porphyrin ring and an iron atom at its centre
Why does the foetal oxygen dislocation curve sit to the left of the adult curve?
Because it has increased affinity for oxygen so it favours oxygen loading at lower partial pressures
What forms when carbon monoxide binds to haemoglobin?
Carboxyhaemoglobin
How is carbon dioxide transported in the blood?
Dissolved in the blood
As bicarbonate
Carbaminohaemoglobin
What is the haldane effect?
As the RBC enters the pulmonary circulation, O2 diffuses across the RBC membrane and binds to hemoglobin. The binding of O2 leads to allosteric changes in hemoglobin (T state to the R state) with loss of H+ and CO2. - effectively oxygen displacing carbon dioxide in the haemoglobin
What’s the product called when oxygen binds to haemoglobin?
Oxyhaemoglobin
