Respiratory mechanisms

Question 1

What are the major inspiratory muscles?

Answer 1

Diaphragm
External intercostal muscles

Question 2

What are the accessory muscles of inspiration?

Answer 2

Sternocleidomastoid
Scalenus
Pectoral

Question 3

What are the muscles of active expiration?

Answer 3

Abdominal muscles
Internal intercostal muscles

Question 4

What is meant by tidal volume?

Answer 4

The normal change in lung volume during resting ventilation

Question 5

What is meant by inspiratory reserve volume?

Answer 5

The difference between maximum lung volume and usual maximum inspiration during resting breathing

Question 6

What is meant by expiratory reserve volume?

Answer 6

The difference between the minimum lung volume and usual maximum expiration during resting breathing

Question 7

What is meant by vital capacity?

Answer 7

The difference between maximum and minimum lung volume

Question 8

What is meant by residual volume?

Answer 8

The air left in the lungs after maximum expiration (You can never get rid of all of the air out of your lungs)

Question 9

What is meant by inspiratory capacity?

Answer 9

The maximum volume of air that can be inspired at the end of normal expiration

Question 10

What is meant by Forces Vital Capacity (FVC)?

Answer 10

The maximum volume that can be forcibly expelled from the lungs following maximum inspiration

Question 11

What is meant by Forced Expiratory Volume in 1 second (FEV1)?

Answer 11

The volume of air that can be expired during the first second of expiration in an FVC determination

Question 12

What is a normal FVC/FEV1 ratio?

Answer 12

Above 75%

Question 13

What is shown by the FVC/FEV1 ratio?

Answer 13

The proportion of forced vital capacity that occurs in the first second

Question 14

What is the formula for airway flow?

Answer 14

Flow = ∆Pressure ÷ Resistance

Question 15

What occurs due to parasympathetic stimulation of the pulmonary smooth muscle?

Answer 15

Bronchoconstriction

Question 16

What occurs due to sympathetic stimulation of the pulmonary smooth muscle?

Answer 16

Bronchodilation

Question 17

What is meant by dynamic airway compression?

Answer 17

Expiration increases intrapleural pressure
This can compress the airways (This becomes worse in those with decreased elastic lung recoil)

Question 18

What are the uses of a peak flow meter?

Answer 18

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

Question 19

What is meant by lung compliance?

Answer 19

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

Question 20

What are some factors that decrease pulmonary compliance?

Answer 20

Pulmonary fibrosis
Pulmonary oedema
Lung collapse
Pneumonia
Surfactant absence

Question 21

What can cause hyperinflation of the lungs?

Answer 21

Compliance can become abnoally increased if the elastic recoil of the lungs is lost
This can occur in emphysema

Question 22

What is meant by work of breathing?

Answer 22

It is a reflection of energy needed to overcome the impeding elements of respiration