0528 - Pulmonary pressures and volumes - EG

Question 1

List the muscles of inspiration.

Answer 1

diaphragm, external intercostals, accessory: scalenes, sternocleidomastoid.

Question 2

List the muscles of expiration.

Answer 2

(only activated in forced breathing as N simply relaxation of muscles of inspiration) internal intercostals, and abdominal muscles (rectus and transverse abdominis, internal and external obliques).

Question 3

What lung volumes comprise vital capacity? What total volume is the VC?

Answer 3

inspiratory reserve volume, tidal volume, expiratory reserve volume. VC ~ 4L

Question 4

What lung volumes comprise functional residual capacity? When is FRC reached?

Answer 4

expiratory reserve volume and residual volume. Reached when all muscles are relaxed.

Question 5

What lung volumes comprise inspiratory capacity?

Answer 5

inspiratory reserve volume and tidal volume.

Question 6

What lung volumes comprise expiratory capacity?

Answer 6

expiratory reserve volume and tidal volume.

Question 7

Why does vital capacity decrease with age?

Answer 7

Residual volume increases due to loss in lung tissue and total lung capacity is lost due to diminished elasticity of tissue.

Question 8

Why is there a hydrostatic pressure difference between the apex and the base of the lung? How is this measured clinically?

Answer 8

Due to a column of blood in lung tissue creating weight; determined by posture and height within thorax. Measured in the oesophagus.

Question 9

How is the pressure and volume related in an alveoli?

Answer 9

P1V1 = P2V2Therefore if the volume of the lungs increases, the pressure will decrease, this is the why air flows into the lungs to equilibrate.

Question 10

What is Ohm’s law? How does this factor in flow of air in the lungs?

Answer 10

P = R * Vthe flow of air will be affected by the resistance of the airways.

Question 11

What is the greatest determinant of resistance in the airway?

Answer 11

the smallest bronchi, followed by the larynx

Question 12

Define compliance. How is it related to elastic recoil?

Answer 12

compliance (C) is the ease of inflation. It is the inverse of elastance (E). E = 1/C. therefore lungs with large compliance have small elastic recoil (emphysema) and lungs with large elastic recoil have small compliance (pulmonary fibrosis)