Respiratory mechanisms Flashcards
What are the major inspiratory muscles?
Diaphragm
External intercostal muscles
What are the accessory muscles of inspiration?
Sternocleidomastoid
Scalenus
Pectoral
What are the muscles of active expiration?
Abdominal muscles
Internal intercostal muscles
What is meant by tidal volume?
The normal change in lung volume during resting ventilation
What is meant by inspiratory reserve volume?
The difference between maximum lung volume and usual maximum inspiration during resting breathing
What is meant by expiratory reserve volume?
The difference between the minimum lung volume and usual maximum expiration during resting breathing
What is meant by vital capacity?
The difference between maximum and minimum lung volume
What is meant by residual volume?
The air left in the lungs after maximum expiration (You can never get rid of all of the air out of your lungs)
What is meant by inspiratory capacity?
The maximum volume of air that can be inspired at the end of normal expiration
What is meant by Forces Vital Capacity (FVC)?
The maximum volume that can be forcibly expelled from the lungs following maximum inspiration
What is meant by Forced Expiratory Volume in 1 second (FEV1)?
The volume of air that can be expired during the first second of expiration in an FVC determination
What is a normal FVC/FEV1 ratio?
Above 75%
What is shown by the FVC/FEV1 ratio?
The proportion of forced vital capacity that occurs in the first second
What is the formula for airway flow?
Flow = ∆Pressure ÷ Resistance
What occurs due to parasympathetic stimulation of the pulmonary smooth muscle?
Bronchoconstriction
What occurs due to sympathetic stimulation of the pulmonary smooth muscle?
Bronchodilation
What is meant by dynamic airway compression?
Expiration increases intrapleural pressure
This can compress the airways (This becomes worse in those with decreased elastic lung recoil)
What are the uses of a peak flow meter?
It gives an estimate of peak flow rate and is useful in testing patients with obstructive lung disease
The best of 3 tests is usually used
What is meant by lung compliance?
The effort that has to go into stretching the lungs
It is the change in lung volume per unit change in transmural pressure gradient across the lung wall
What are some factors that decrease pulmonary compliance?
Pulmonary fibrosis
Pulmonary oedema
Lung collapse
Pneumonia
Surfactant absence
What can cause hyperinflation of the lungs?
Compliance can become abnoally increased if the elastic recoil of the lungs is lost
This can occur in emphysema
What is meant by work of breathing?
It is a reflection of energy needed to overcome the impeding elements of respiration
