Resp Misc. Flashcards
How is ventilation in the lungs achieved?
By the expansion of the thoracic cavity and lungs during inspiration. This reduces the intra alveolar pressure and transmural pressures, which encourages gas to travel down the pressure gradient from the atmosphere into the lungs.
How is expiration achieved?
By the recoil of the lungs following active expansion
Is expiration an active or passive process?
Largely passive
In expiration, how is recoil achieved?
Due to elastic connective tissue and alveolar surface tension
How is alveolar surface tension created?
By the attraction between the water molecules at the liquid – air surface, which creates a natural tendency for the alveoli to collapse
What reduces alveolar surface tension?
The presence of a pulmonary surfactant, which acts to intersperse the water molecules on the surface of the lungs
What is meant by the term ‘tidal volume’?
The volume of air entering and leaving per breath
What is meant by the term ‘inspiratory reserve volume’?
The extra volume which the lungs can inspire above tidal volume
What is meant by the term ‘inspiratory capacity’?
The maximal volume of air that can be inspired: TV + IRV
What is meant by the term ‘expiratory reserve volume’?
Extra volume of air that can be expired above tidal volume
What is meant by the term ‘residual volume’?
Minimum volume of air remaining in the lungs after expiration
What is meant by the term ‘functional residual volume’?
Volume of air in lungs at the end of normal, passive respiration (RV+ ERV)
What is meant by the term ‘vital capacity’?
Maximal volume of air that can be moved out of the lungs following a maximal respiration
What is meant by the term ‘total lung capacity’?
Maximum volume of air that the lungs can hold
For a healthy young male, what is the average tidal volume?
500mls
For a healthy young male, what is the average inspiratory reserve volume?
3000mls
For a healthy young male, what is the average inspiratory capacity?
3500mls
For a healthy young male, what is the average expiratory reserve volume?
1000mls
For a healthy young male, what is the average reserve volume?
1200mls
For a healthy young male, what is the average functional reserve capacity?
2200mls
For a healthy young male, what is the average vital capacity?
4500mls
For a healthy young male, what is the average total lung capacity?
5700mls
How do you calculate pulmonary ventilation?
Tidal volume * Respiratory rate
What is meant by the term ‘anatomical dead space’?
The volume of air that remains in the airways and doesn’t pass into the alveoli
What is meant by the term ‘alveolar dead space’?
The alveoli which are ventilated but not perfused and therefore cannot take part in respiration
What are the four main factors affecting ventilation?
Partial pressure of O2 / C02
Diffusion coefficient
Surface area
Membrane thickness
What is the majority of oxygen bound to?
Haemoglobin
What is the Bohr effect?
It describes a rightward shift in 02 dissociation, which means more oxygen is unloaded at the same PC02
What mediates the Bohr effect?
Increased P02, temperature, 2,3-Bisphosphoglyceric acid and acidosis
What are the three way carbon dioxide can be transported?
Free C02
Carb-amino compounds
Bicarbonate
What is the primary driver of respiration?
The pre-botzinger complex in the medulla