Physiology Flashcards
(25 cards)
What are the forces keeping the alveoli open?
Transmural pressure gradient
Pulmonary surfactant
Alveolar interdependance
What are the forces promoting alveolar collapse?
Elasticity of stretched pulmonary connective tissue
Alveolar surface tension
At what point in pregnancy do babies produce their own surfactant?
Very late pregnancy
What problem do premature babies often experience?
Respiratory distress syndrome as they cannot produce enough alveoli surfactant to prevent lung collapse so they have to breathe extremely strenuously
What is boyle’s law?
At any constant temperature the pressure exerted by a gas varies inversely with the volume of the gas
What are the two forces that hold the lungs to the chest wall?
The cohesive force of the intrapleural fluid
Negative intrapleural pressure
What is tidal volume?
Volume of air entering or leaving the lungs during a single breath
What is inspiratory reserve volume?
Extra volume of air that can be maximally inspired over and above the typical resting tidal volume
What is inspiratory capacity?
Maximum volume of air that can be inspired at the end of a normal quiet expiration
What is expiratory reserve volume?
Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume
What is residual volume?
Minimum volume of air remaining in the lungs even after a maximal expiration
What is functional residual capacity?
Volume of air in lungs at end of normal passive expiration
What is vital capacity?
Maximum volume of air that can be moved out during a single breath following a maximal inspiration
What is total lung capacity?
Maximum volume of air that the lungs can hold
What is forced expiratory volume in one second? (FEV1) (Dynamic volume)
Volume of air that can be expired during the first second of expiration in an FVC (Forced Vital Capacity) determination
What is pulmonary compliance?
The measure of effort that has to go into stretching the lungs upon inspiration
What can decrease pulmonary compliance?
Pulmonary fibrosis Pulmonary oedema Lung collapse Pneumonia Absence of surfactant
What can increase pulmonary compliance?
Emphysema
What is pulmonary ventilation?
The volume of air breathed in and out per minute
What is alveolar ventilation?
The volume of air exchange between the atmosphere and alveoli per minute
What are the 4 factors that affect the rate of gas exchange across alveolar membrane
- Partial pressure gradient of O2 and CO2
- Diffusion coefficient
- Surface area
- Membrane thickness
What is Dalton’s law?
The sum of the partial pressures of each individual component in the gas mixture
What is ficks law?
The amount of gas that moves across a membrane is proportional to the area of the membrane but inversely proportional to its thickness
What is Henry’s law?
The amount of a given gas dissolved in a given type and volume of liquid at a constant temp is proportional to the partial pressure of the gas in equilibrium with the liquid
