Respiratory Handout

Lecture 2:

Transmural Pressures (Pressures across a Wall):

Transpulmonary and Trans-Chest-Wall Pressures.

For lungs to function normally and to prevent lungs from collapsing,

For lungs to function normally and to prevent lungs from collapsing:

The intrapleural pressure must be lower than alveolar pressure!

Normal FEV1/FVC ratio:

Normal FEV1/FVC ratio = 0.7 to 0.8

Below are NOT highlighted:

• meaning that about 70-80% of the vital capacity can be expired in the first second of forced expiration.

• Younger and taller people tend to have higher normal FEV1/FVC ratio.

In obstructive diseases such as asthma:

In obstructive diseases such as asthma:

both FVC and FEV1 are decreased, FEV1/FVC is also decreased

Below are NOT Highlighted:

• Because decrease in FEV1 is often more pronounced than that in FVC

Changes in pulmonary arteriolar resistance and blood flow are controlled by:

mainly by local factors, primarily PA(O2)

The normal overall ratio of alveolar ventilation (Va, L/min, normally 4 L/min) to pulmonary blood flow (Q, L/min, normally 5L/min) is approximately

4/5=0.8