Ventilation and Compliance Flashcards
What is the average total lung capacity?
6L
What is tidal volume?
The volume of air breathed in and out when the person is breathing normally (500ml)
What is residual volume?
The volume of air left in the lungs after expiration - cannot be breathed out
Why do we have a residual volume left in our lungs after expiration?
It stops our alveoli collapsing
What is the inspiratory reserve volume?
The maximum volume of air that can be breathed in
What is the expiratory reserve volume?
The maximum volume of air that can be exhaled
What is anatomical dead space?
The volume occupied by the conducting airways which is not available for gas exchange
What is FEV1?
Forced expired volume in one second
What is pulmonary ventilation?
The total air movement into and out of the lungs in L/min
What is alveolar ventilation?
The fresh air getting to the alveoli and therefore available for gas exchange in L/min
What is the partial pressure of the oxygen in the air we breathe in?
160 mmHg (21 kPa)
What is the main role of surfactant
To reduce the surface tension on the alveolar surface membrane and reduce the tendency for the alveoli to collapse
How does surfactant make breathing easier?
It increases lung compliance and reduces the lung’ s tendency to recoil
Why is surfactant more effective in small alveoli compared to large alveoli?
In smaller alveoli the surfactant molecules are closer together and are therefore more concentrated
What is compliance?
The change in volume relative to the change in pressure - the elasticity of the lungs
What is the difference between obstructive and restrictive lung disease?
Obstructive is where there is an obstruction of the airflow especially on expansion.
Restrictive is when there is a restriction of lung expansion
What lung disorders are classed as obstructive?
Asthma and COPD
What lung disorders are classed as restrictive?
Fibrosis, Infant Respiratory Distress Syndrome, Oedema and Pneumothorax
What are the two classifications of Spirometry?
Static (volume exhaled) and Dynamic (time taken to exhale a certain volume)
What lung volumes can be directly measured by spirometry
Tidal volume, expiratory reserve volume, inspiratory reserve volume, inspiratory capacity and vital capacity
What is the normal FEV1 in fit, healthy young adult males?
4L
What is the normal FVC in fit, healthy young adult males?
5L
What is the normal FEV1/FVC?
80%
What happens to FEV1/FVC in someone with an obstructive lung disease
It decreases significantly
What happens to FEV1/FVC in someone with a restrictive lung disease?
It may increase or stay the same (Both FEV1 and FVC drop significantly so the ratio stays roughly the same)
At what stage during our development do we start producing surfactant?
Approx 25 weeks gestation (complete by approx 36 weeks)
