Respiratory Physiology 2 Flashcards
What is Tidal Volume?
The volume of air breathed in and out with each breath.
What is the Expiratory Reserve Volume?
The maximum volume of air that can be expelled from the lungs at the end of a normal respiration.
What is the inspiratory reserve volume?
The maximum volume of air which can be inhaled at the end of a maximal expiration.
What is the Residual Volume?
The volume of gas in the lungs at the end of a maximal expiration.
What does Vital Capacity refer to?
Tidal volume, inspiratory reserve volume and expiratory reserve volume together.
What is meant by Total Lung Capacity?
Vital capacity plus the residual volume.
What is meant by Inspiratory Capacity?
Tidal volume plus inspiratory reserve volume.
What is meant by Functional Residual Capacity?
Expiratory Reserve Volume plus Residual volume.
What membrane lines the lungs?
The visceral pleural membrane.
What membrane lines the inner surface of the ribs?
The parietal pleural membrane. Between the parietal and visceral membranes lies the intrapleural sac.
What does Boyle’s law state?
That pressure exerted by a gas is inversely proportional to it’s volume.
What are the primary muscles of inspiration?
External intercostals and the diaphragm.
What muscles are used in expiration?
Passive at rest but if needed internal intercostals and abdominal muscles can be used.
What is the Intra-thoracic Pressure?
Basically pressure inside the lungs. May be positive or negative relative to atmospheric pressure.
What is meant by Intra-pleural Pressure?
Pressure in pleural cavity, negative in healthy lungs.
What is meant by transpulmonary pressure?
Difference between alveolar or intra-thoracic pressure. Almost always positive because PT = Palv – Pip and Pip is negative.
How might a pneumothorax occur?
Air enters pleural cavity due to injury, this causes intra pleural pressure to rise causing the lung to collapse.
What drives airflow into the lungs?
Sub atmospheric alveolar pressure caused by chest expansion.
In a healthy person what drives expiration?
Inspiratory muscles stop contracting allowing the elastic recoil of the chest wall and lungs to return them to their original size.
What is surfactant and what does it do?
It’s a detergent like fluid secreted by type II pneumocytes. It reduces surface tension on the alveolar surface preventing their collapse. This increases compliance and makes breathing easier.
In what alveoli is surfactant most effective?
Small alveoli rather than large as surfactant molecules come closer together and are therefore more concentrated.
In what gestational period does surfactant production develop?
From 25-36 weeks. It is stimulated by thyroid hormones and cortisol.
What is Infant Respiratory Distress Syndrome?
Disease suffered by premature babies due to insufficient surfactant production.
What is meant by compliance?
Change in volume relative to change in pressure. It represents the stretchability of the lungs.
