Respiratory 3 & 4 Flashcards
(36 cards)
Define residual volume.
Air that the lung cannot dispel.
(the alveoli is always partially inflated as this makes it easier for the lung to inflate and provides a reservoir of air to allow gas exchange at all times)
What is the term for the amount of air that can be expired from the lungs by determined effort after normal inspiration?
Expiratory reserve volume
Define functional residual capacity.
The normal amount of air left after normal expiration.
It is the sum of the residual volume and the expiratory reserve volume.
What is the term used to define the amount of air which enters the lung during normal inspiration?
Tidal volume.
The same amount will leave the lung during expiration.
Define the term inspiratory reserve volume.
The amount of air inhaled above the tidal volume upon taking a deep breath.
What is the term used to define the maximum amount of air that can be inspired?
The inspiratory capacity.
It is the sum of the tidal volume and the inspiratory reserve volume.
Define the term vital capacity.
The maximum amount of air that can be expired.
It is the sum of the expiratory reserve volume, the tidal volume and the inspiratory reserve volume.
What is the term used to define the sum of the vital capacity and the residual volume?
Total lung capacity
What is anatomical dead space?
Air that fills the conducting airways upon inspiration that will be exhaled without undergoing gas exchange.
It is usually 150ml.
What are the two types of ventilation?
- pulmonary (minute) ventilation
- alveolar ventilation
What is pulmonary ventilation?
The total air movement into/out of the lungs.
What is alveolar ventilation?
The fresh air that reaches the alveoli and therefore is available for gas exchange.
(This is functionally more significant than pulmonary ventilation)
What must be taken into account in order to calculate the alveolar ventilation?
The anatomical dead space.
What occurs as a result of hyper-ventilation?
- increased alveolar ventilation
- PO2 rises
- PCO2 falls
Is the feeling of ‘breathlessness’ more susceptible to changes in oxygen or carbon dioxide?
Carbon dioxide
What is surfactant and what is it’s function?
A detergent-like fluid produced by type II alveolar cells.
It reduces surface tension on the alveolar surface membrane.
What does the term surface tension refer to and where does it occur?
Surface tension refers to the attraction between water molecules.
It occurs wherever there is an air-water interface.
How does surfactant combat surface tension?
Surface tension creates an inwardly directed pressure that wants to collapse the alveoli.
Surfactant negates this by sitting in-between the water molecules and reducing the directed pressure, and therefore increasing lung compliance.
Is there greater pressure in smaller alveoli or larger alveoli?
There is greater pressure in smaller alveoli.
Why do premature babies suffer Infant Respiratory Distress Syndrome?
Babies born before 36 weeks gestation have incomplete surfactant production, meaning the pressure required to inflate the alveoli is too great.
How is IRDS treated?
Synthetic surfactant administered via aerosols.
What are the lungs filled with in utero?
Saline
This means there is no surface tension to overcome.
What is compliance?
The change in volume relative to the change in pressure.
ie. how much volume changes for any given pressure
Define high compliance.
A large increase in lung volume for a small decrease in intrapleural pressure.
