Pulmonary Lecture 1

Question 1

What are the inspiratory Muscles?

Answer 1

Diaphragm Intercostals

Question 2

What are the expiratory muscles?

Answer 2

There are none during quiet normal breathing During forced expiration muscles in abdominal wall

Question 3

What is the intrapleural space filled with

Answer 3

Water

Question 4

How does the lung attach to the chest wall?

Answer 4

Due to the Negative Intrapleural pressure (vacuum) Think of how a cup sticks to a table when there is water between the two

Question 5

What is the Intrapleural Pressure negative?

Answer 5

This is because the intrinsic size of the lung is smaller than what it is in the body. Thus the lung is trying to always shrink in size

Question 6

How does the chest wall effect the intrinsic Equilibrium?

Answer 6

The lung is trying to “deflate” and the chest wall is trying to “inflate” causing opposing forces on the intrapleural space causing it to be negative This causes the lung to always stick to your chest

Question 7

What is the typical values of Intrapleural pressure during inspiration and expiration?

Answer 7

-5 cm-H20 @ end of expiration -30cm-H20 @ end of inspiration

Question 8

What happens to the lung during a pneumothorax bullet wound

Answer 8

The bullet disrupts the hydraulic connection between lung and chest wall Causes the lung to collapse to its intrinsic size. The chest wall will also inflate

Question 9

What are the steps of inspiration?

Answer 9

Contraction of inspiratory Muscles –> Inflation of chest cavity–> Inflation of lung–>Inward Air-Flow

Question 10

How is direction and amount of airflow defined?

Answer 10

the pressure difference of the air at the mouth (atm) and air at the lung Flow = (Patm-Plung)

Question 11

How is dynamic pressure associated with inspiration airflow?

Answer 11

Air enters the lungs causing it to inflate. the forces that cause inflation cause a negative pressure driving inward airflow, but then as the air dissipates the pressure increases again

Question 12

How does dynamic pressure effect expiration?

Answer 12

The wall of the lungs are moving inward (deflating) during expiration causing a positive pressure.

Question 13

What is the elastic recoil pressure?

Answer 13

This is the pressure caused during expiration:

The lung is in a more inflated state than its intrinsic equilibrium. During expiration the lung is recoiling towards this equilibrium

Question 14

Define Lung Compliance

Answer 14

A measure of how easily an applied pressure induces a volume change:

Example:
New balloon - Hard to blow up - low compliance - more rigid

Used balloon - easier to blow up - high compliance

Question 15

How is applied pressure and lung volume associated

Answer 15

As more pressure is applied, the lung volume goes up

Question 16

Define Transpulmonary Pressure

Answer 16

A function of the pressure in the lung - The pressure specifically in the Intrapleural space

P_TP=P_Lung-PIP

Question 17

How does emphysema effect the lung

Answer 17

There is a destruction of elastin (gives the walls integrity) Elastin is a major protein involved in recoil.

Emphysema has less elastin causing a more shallow recoil “Floppy Lung”. When lung inflates it hangs out longer increasing compliance

Question 18

How does pulmonary fibrosis effect lung compliance

Answer 18

The rigidity of pulmonary fibrosis causes decreased compliance

Question 19

(T/F) Emphysema will cause problems with expiration

Answer 19

True

Question 20

(T/F) Pulmonary Fibrosis will cause problems with inspiration

Answer 20

true

Question 21

Define Surface Tension

Answer 21

Forces that arise due to favorable water-water interactions and unfavorable air-water interactions

Question 22

How is the alveolus affected by surface tension?

Answer 22

The alveolus is surrounded by a thin layer of water because cells cannot live when just exposed to air.

This causes a very energetically unfavorable environment

Surface tension will cause the alveolus to become smaller so that the water layer is thicker and energetically favorable

Question 23

How does surfactant assist with the alveolus surface tension problem?

Answer 23

Sufractant has a polar and non polar end:

They swim out to the surface and are oriented with the polar end setting agains the water molecules and non polar ends against the air

Can maintain a relatively inflated alveolus with thin water layers because of the surfactant molecules. They form an energetically favorable environment

Question 24

What is respiratory distress syndrome?

Answer 24

A disorder with reduced surfactant:

Occurs often in premature babies - they have no developed the ability to breath as they have not yet developed surfactant

Causes decreased lung compliance
Water accumulation in lung
Collapse of small alveoli