Pulmonary Lecture 1 Flashcards
What are the inspiratory Muscles?
Diaphragm Intercostals
What are the expiratory muscles?
There are none during quiet normal breathing During forced expiration muscles in abdominal wall
What is the intrapleural space filled with
Water
How does the lung attach to the chest wall?
Due to the Negative Intrapleural pressure (vacuum) Think of how a cup sticks to a table when there is water between the two
What is the Intrapleural Pressure negative?
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
How does the chest wall effect the intrinsic Equilibrium?
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
What is the typical values of Intrapleural pressure during inspiration and expiration?
-5 cm-H20 @ end of expiration -30cm-H20 @ end of inspiration
What happens to the lung during a pneumothorax bullet wound
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
What are the steps of inspiration?
Contraction of inspiratory Muscles –> Inflation of chest cavity–> Inflation of lung–>Inward Air-Flow
How is direction and amount of airflow defined?
the pressure difference of the air at the mouth (atm) and air at the lung Flow = (Patm-Plung)
How is dynamic pressure associated with inspiration airflow?
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
How does dynamic pressure effect expiration?
The wall of the lungs are moving inward (deflating) during expiration causing a positive pressure.
What is the elastic recoil pressure?
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
Define Lung Compliance
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
How is applied pressure and lung volume associated
As more pressure is applied, the lung volume goes up
Define Transpulmonary Pressure
A function of the pressure in the lung - The pressure specifically in the Intrapleural space
PTP=PLung-PIP
How does emphysema effect the lung
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
How does pulmonary fibrosis effect lung compliance
The rigidity of pulmonary fibrosis causes decreased compliance
(T/F) Emphysema will cause problems with expiration
True
(T/F) Pulmonary Fibrosis will cause problems with inspiration
true
Define Surface Tension
Forces that arise due to favorable water-water interactions and unfavorable air-water interactions
How is the alveolus affected by surface tension?
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
How does surfactant assist with the alveolus surface tension problem?
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
What is respiratory distress syndrome?
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
