sites of airway resistance Flashcards
What is airway resistance?
The resistance offered to the passage of air through the respiratory tract.
Airway resistance only exists when air is flowing.
How does total airway resistance change during inspiration and expiration?
Total airway resistance becomes less during inspiration and greater during expiration.
This is due to changes in the airway radius.
Where is airway resistance not uniformly distributed?
Airway resistance is not distributed uniformly along the respiratory tract.
Almost half of the total resistance is found in the nose, pharynx, and larynx.
What happens to the vocal folds during inspiration?
The vocal folds reflexly open, reducing resistance.
During expiration, the vocal cords come close together, forming an ‘expiratory brake’.
Where does the majority of airway resistance reside in the lower airways?
In the trachea and bronchi.
About 80% of the remaining resistance below the larynx is in these areas.
In which airways does the greatest resistance to flow occur?
In medium-sized airways (fourth to eighth generation).
This is where the greatest resistance is encountered in the respiratory system.
What factors determine airway resistance?
Tube length, tube radius, and primarily the radius of the tube.
Airway resistance is inversely proportional to the fourth power of the airway radii.
Which parts of the bronchial tree are most important in controlling airway resistance?
The smaller bronchi and bronchioles.
These areas have walls containing innervated smooth muscle that can contract to reduce diameter.
Fill in the blank: Airway resistance is inversely proportional to the _______.
fourth power of the airway radii.
