Physiology 2 Flashcards
What is the tidal volume and average value?
- The volume of air entering or leaving the lungs during a single breath
- 500 ml
What is the inspiratory reserve volume and average value?
- The extra volume of air that can be maximally inspired over and above the typical resting tidal volume
- 3000 ml
What is the inspiratory capacity and average value?
- Maximum volume of air that can be inspired at the end of a normal quiet expiration.
- 3500 ml
How is Inspiratory capacity related to inspiratory reserve volume and tidal volume?
IC= IRV + TV
What is the expiratory reserve volume and average value?
- The extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume
- 1000 ml
What is the residual volume and average value?
- Minimum volume of air remaining in the lungs even after a maximal expiration
- 1200 ml
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What is the functional residual capacity and average value?
- The volume of air in the lungs at the end of a normal passive expiration
- 2200 ml
How is functional residual capacity related to expiratory reserve volume and residual volume
FRC= ERV + RV
What is vital capacity and average volume?
- Maximum volume of air that can be moved out during a single breath following a maximal inspiration
- 4500 ml
How is vital capacity related to Inspiratory reserve volume, tidal volume and expiratory reserve volume?
VC= IRV + TV + ERV
What is total lung capacity and average volume?
- maximum volume of air that the lungs can hold.
- 5700 ml
How is total lung capacity related to vital capacity and residual volume?
TLC= VC + RV
What is the forced expiratory volume in one second (FEV1): Dynamic volume
The volume of air that can be expired during the first second of an expiration in an FVC determination
What is the FEV1%?
What is the normal value?
The FEV1/FVC ratio
Normal value >75%
What values can be determined from a volume time curve? (3)
The FVC, FEV1 and FEV1%
What are the FVC, FEV1 and FEV1/FVC values in normal spirometry
FVC: Normal
FEV1: Normal
FEV1%: Normal
What are the FVC, FEV1 and FEV1/FVC values in airway obstruction?
FVC: Low or normal
FEV1: Low
FEV1%: Low
What are the FVC, FEV1 and FEV1/FVC values in lung restriction?
FVC: Low
FEV1: Low
FEV1%: Normal
What are the FVC, FEV1 and FEV1/FVC values in a combination of obstruction and restriction?
FVC: Low
FEV1: Low
FEV1%: Low
What is the formula for airway resistance (Flow)
Flow= Change in pressure/Resistance
What effect does the parasympathetic branch of the autonomic nervous system have on bronchial smooth muscle?
Bronchoconstriction
What effect does the sympathetic branch of the autonomic nervous system have on bronchial smooth muscle?
Bronchodilation
What are the accessory muscles of inspiration? (2)
Sternocleidomastoid
Scalenues
What are the muscles of active expiration?
Internal intercostal muscles
Abdominal muscles
How are the airways held open by dynamic airway compression?
Increase in airway pressure upstream
Airways opened by increasing driving pressure between the alveolus and airway (Pressure downstream)
How does an airway obstruction (COPD or asthma) affect driving pressure between alveolus and airway?
Driving pressure between alveolus and airway is lost over obstructed segment
Fall in airway pressure downstream–> Airway collapse caused by rising pleural pressure during active expiration.
What does peak flow rate assess?
Airway function
What is peak flow useful in diagnosis of?
Obstructive diseases
What is pulmonary compliance?
The effort that has to go into stretching or distending the lungs.
Less compliance= More work require to inflate lungs
Name some factors that cause decreased pulmonary compliance. (5)
- Pulmonary fibrosis
- Pulmonary oedema
- Lung collapse
- Pneumonia
- Absence of surfactant
How does emphysema relate to pulmonary compliance?
Abnormally increased pulmonary compliance.
Patients have to work harder to get air out of the lungs.
What factors cause work of breathing to increase?
- When pulmonary compliance is increased
- When airway resistance is increased
- When elastic recoil is decreased
- When there is need for increased ventilation
