Lecture 9: Ventilation Mechanisms Flashcards
What are the three steps of respiration? What is happening during each step?
- pulmonary ventilation: air enters alveoli
- external respiration: alveoli and capillary exchange
- internal respiration: capillary and cell exchange
Pulmonary ventilation requires a change in _____, with the air moving down a ________ __________.
Pressure, pressure gradient
What is boyle’s law?
Pressure of gas in a closed container is inversely proportional to the volume of the container (when mass/temp are constant)
What is standard intrapleural pressure?
-4mmHg
In order to breath in, air must move _______ its ______ _______. What is standard atmospheric pressure?
Down, pressure gradient, 760mmHg
What are the 3 muscles only used during active breathing?
Sternocleidomastoid, scalene, pectoralis minor
What factors do elastance and compliance play in pulmonary ventilation?
Elastance = collapsing force using collagen and elastin.
Compliance = distensibility of the lung, related to elasticity and surface tension.
What happens to pulmonary compliance with pulmonary TB?
Pulmonary compliance decreases in pulmonary TB because of the thickening/scarring of elastic lung tissue, making it harder for the lungs to expand.
What is emphysema?
Long-term exposure to toxic chemicals, leading to destruction of lung tissue (especially elastase)
Surfactant is a biological ______, breaking up the _______ _________ of water within the lung.
Detergent, surface tension
What produces surfactant? What does surfactant prevent?
Produced by type II pneumocytes in the alveoli. Prevents atelectasis, or the collapse of the alveoli.
What happens when surfactant is not present on the alveoli?
Attractive forces create high surface tension, pulling molecules together and collapsing the alveoli.
What occurs during RDS?
Respiratory distress syndrome - difficult for infant to breathe due to lack of surfactant. May be cyanotic, require CPAP/supplemental oxygen or surfactant.
What is spirometry?
The study of flow-volume curves, a statistical way of measuring how much/how quickly air is being exchanged.
