Ventilation and Lung Volumes Flashcards
Describe the difference between conduction zone and respiratory zone in ventilation.
Conduction zone:
- Respiratory passages that carry air to sites of gas exchange
- Filters, warms and humidifies air.
Describe the alveolar blood supply
Pulmonary capillaries occupy 70-80% of alveolar surface area.
These receive 100% of cardiac output.
Name the two pleural layers and describe 3 roles
Visceral (inner) and parietal (outer) pleura.
- Reduction of friction
- Create suction
- Compartmentalisation to protect against infection
Describe pleural, trans-airway and trans-pulmonary pressure
Pleural pressure must be negative to support the suction of the pleura to support the lungs.
Trans-airway pressure (airway pressure - pleural pressure) must be positive ot prevent airway collapse on exahalation.
Trans-pulmonary pressure (alveolar pressure - pleural pressure) must be positive to prevent lung collapse
What is the normal inspiratory reserve volume?
Amount of air that can be inahled AFTER tidal inhalation
- 3000mL
What is the normal expiratory reserve volume?
Amount of air that can be exhaled after normal tidal inhalation
- 1200mL
What is the normal residual volume?
Amount of air remaining after forced exhalation - 1200mL
What is the normal total lung capacity?
6000mL
What is the normal vital capacity?
Maximum amount of air that can be expired after maximum inspiratory effort. Total lung volume (6000) minus residual volume (1200) = 4800mL
What is functional residual capacity?
Volume of air remaining in lungs after normal tidal expiration. Residual volume (1200) + expiratory reserve volume (1200) = 2400mL
What is dead space?
Inspired air that doesn’t contribute to gas exchange. Volume of conducting zone conduits - 150mL
What is the difference between minute ventilation and alveolar ventilation?
Minute ventilation = Tidal volume x Frequency
Alveolar ventilation = (Tidal volume - Deadspace) x Frequency
