Changes In Pleural Pressure During Respiration

Question 1

What is the functional residual capacity?

Answer 1

The volume when the respiratory muscles are relaxed (at end of passive expiration)

Question 2

What will the pleural pressure be in respect to alveolar pressure when;

The lungs are recoiled and chest wall expanded

Answer 2

Pleural pressure will be less than alveolar

Question 3

When is equilibrium reached?

Answer 3

When the force generated by the pressure gradient across the alveolar wall is equal to elastic recoil

Question 4

Why is there no airflow at functional residual capacity?

Answer 4

Because alveolar pressure = atmospheric pressure

Question 5

What do the pressure gradients need to be for inspiration?

Answer 5

Atmospheric pressure needs to be greater than alveolar pressure

Question 6

What do the pressure gradients need to be for expiration?

Answer 6

Alveolar pressure needs to be greater than atmospheric pressure

Question 7

For no airflow, what do the conditions need to be?

Answer 7

Relaxed diaphragm = pleural pressure less than alveolar pressure
Alveolar pressure = atmospheric pressure

Question 8

What creates a decrease in pleural pressure?

Answer 8

Contraction in the diaphragm enlarges the pleural space = pleural pressure decreased

Question 9

What conditions need to be present for air to flow in?

Answer 9

When pleural pressure is less than alveolar
Alveolar space enlargens
Alveolar pressure decreases

Alveolar pressure less than atmospheric = airflow in