Physiology 2 (Week 1) Flashcards
What is tidal volume?
The volume of air entering or leaving the lungs during a single breath
What is the average tidal volume in a healthy person?
500ml
What is inspiratory reserve volume?
The maximum volume of air that can be inspired over and above the tidal volume
What is the average inspiratory reserve volume in a healthy person?
3000ml
What is inspiratory capacity?
The maximum volume of air that can be inspired after a normal expiration
IC = Inspiratory reserve volume + Tidal volume
What is expiratory reserve volume?
The extra volume of air that can be actively expired after the normal, tidal volume
What is the average expiratory reserve volume in a healthy person?
1000ml
What is the average inspiratory capacity in a healthy person?
3500ml
What is residual volume?
The minimum volume of air remaining in the lungs even after a maximal expiration
What is the average residual volume in a healthy person’s lungs?
1200ml
What is functional residual capacity?
The volume of air in the lungs after a normal passive expiration
FRC = Expiratory reserve volume + Residual volume
What is the average functional residual capacity in a healthy person?
2200ml
What is vital capacity?
The maximum volume of air that can be moved out during a single breath following a maximal inspiration
VC = Inspiratory reserve volume + Tidal volume + Expiratory reserve volume
What is the average vital capacity in a healthy person?
4500ml
What is total lung capacity?
The maximum volume of air that the lungs can hold
What is the average total lung capacity in a healthy person?
5700ml
Give a word equation for total lung capacity.
Total lung capacity = Vital capacity + Residual volume
What happens to the residual volume when elastic recoil of the lungs is lost?
Residual volume increases
Give an example of a disease which reduces elastic recoil of the lungs.
Emphysema
Dynamic lung volumes are useful in the diagnosis of _____ and ____ lung disease.
obstructive , restrictive
What is Forced Vital Capacity (FVC)?
The maximum volume of air which can be forcibly expelled from the lungs following a maximal inspiration
What is FEV1?
Forced Expiratory Volume in 1s - the volume of air which is expelled during the first second of an FVC determination.
What is the FEV1/FVC ratio?
The proportion of the forced vital capacity which can be expired in the first second of an FVC determination
What range of FEV1/FVC ratio values is normal for a healthy person?
> 70%
In obstructive lung disease, the FEV1/FVC ratio is usually…
< 70%
Why is the FEV1/FVC ratio reduced in obstructive lung disease?
It takes long for the lungs to expire the same volume of air
Why, in restrictive lung disease, does the FEV1/FVC ratio still have a value > 70%?
Both FEV1 and FVC are reduced - ratio remains the same.
Give an equation for flow rate of air in the lungs.
F = deltaP / R
i.e Flow = Change in pressure / Resistance
What is the primary determinant of airway resistance?
Radius of airway (r)
Parasympathetic stimulation causes _____.
bronchoconstriction
Sympathetic stimulation causes ____.
bronchodilatation
Which division of the nervous system causes bronchoconstriction?
Parasympathetic division
Which division of the nervous system causes bronchodilatation?
Sympathetic division
Name two diseases which significantly increase airway resistance.
COPD
Asthma
With regard to inspiration and expiration:
_____ is more difficult than _____.
Expiration , inspiration
_____ is difficult for patients with airway obstruction.
Expiration
During expiration, intrapleural pressure _____.
increases
What is a consequence of increasing intrapleural pressure during expiration in patients with airway obstructions?
Compression of the airways and alveoli
In normal people, increased airway resistance caused by compression downstream results in…
Increased airway pressure upstream
Opening of the airway by driving pressure
In people with airway obstruction, increased airway resistance caused by compression downstream results in…
Increased airway pressure upstream
Driving pressure is lost over the obstructed segment
Decrease in downstream pressure
Airway collapse
What is the name of the process in which airways and alveoli are compressed by the pleura, caused by variable pressures during inspiration and expiration?
Dynamic airway compression
What exacerbates dynamic airway compression?
Decreased elastic recoil of the lungs (e.g in emphysema, COPD)
A peak flow meter gives an estimate of ___ ___ ___.
peak flow rate
What does peak flow rate give an indication of?
Airway function
How is peak flow rate measured during a consultation with a patient?
- Patient a short, sharp blow into peak flow meter
2. Best of three attempts taken as peak flow rate
During inspiration, the lungs are _____.
stretched
What is a colloquial definition of pulmonary compliance?
The effort that goes into stretching the lungs
What is the scientific definition of pulmonary compliance?
Volume change per unit of pressure change across the lungs
The less compliant the lungs are, the more ___ required to produce sufficient inflation.
work
Name two factors which reduce pulmonary compliance.
Pulmonary fibrosis Pulmonary oedema Lung collapse Pneumonia Lack of pulmonary surfactant
Why do the lungs feel stiff in patients with reduced pulmonary compliance?
A greater change in pressure is required to produce the same change in volume
What sensation do patients with reduced pulmonary compliance feel during exertion?
Shortness of breath
In spirometry, reduced pulmonary compliance presents what type of lung disease?
Restrictive lung disease
When the elastic recoil of the lungs is lost, pulmonary compliance _____.
increases
Name a disease which can result in increased pulmonary compliance.
Emphysema
What is a sign associated with increased pulmonary compliance?
Hyperinflation of the lungs
Pulmonary compliance increases with ___.
age
What is the name given to the outward appearance of effort going into breathing?
Work of breathing
Roughly what percentage of energy expenditure goes into the work of breathing?
3%
How full are the lungs normally?
Around half-full
Name two cases in which the work of breathing would increase.
- Pulmonary compliance decreases
- Airway resistance increases
- Elastic recoil decreases
- When there is a need for increased ventilation
