VIII: Modifications in Pulmonary Vascular Resistance Flashcards
What increases as flow increases
Pressure
Increased pressure and flow can result in
Pulmonary edema
How is pulmonary edema prevented when there is an increase in flow
Through an increase in the number and size of blood vessels
Mechanisms that reduce resistance
Recruitment
Distension
Definition of recruitment
Opening of pre-existing blood vessels
When does recruitment occur
When there is an increase in pressure
What is distension
The vasodilation of already developed vessels
When does distension occur
When pressure drops
Result of both mechanisms
Increased blood flow and avoids high blood pressure and pulmonary edema
Mechanism to improve V/Q ratio during EXERCISE
Zones transform into Zone 2 because it has the best ratio of ventilation / perfusion
What are the 2 types of vessels
Alveolar vessels
Extra-alveolar vessels
By what are alveolar vessels conditioned
By alveolar pressure and alveolar permeability to gas exchange
How are alveolar vessels impacted during deep inspiration
During deep inspiration, volume of alveolus increases –> vessel suffers compression –> decrease in diameter of blood vessels –> increase in vascular RESISTANCE
Are extra-alveolar vessels in contact with the alveoli
No
Comparison in size during inspiration between alveolar vessels and extra-alveolar vessels
Alveolar vessels are compressed during inspiration
Extra-alveolar vessels increase in size during inspiration
How do extra-alveolar vessels react to changes in parenchyma
They will increase/decrease in size, elasticity and distensibility
Deep forced inspiration effect on alveolar and extra-alveolar vessels
Increase in ALVEOLAR PRESSURE –> closure of alveolar blood vessels (due to an increase in alveolar volume) + increased size of extra-alveolar vessels
INCREASED RESISTANCE of alveolar vessels
Deep forced expiration effect on alveolar and extra-alveolar blood vessels
Increased contraction force –> total closure of extra alveolar blood vessels
INCREASED RESISTANCE of extra-alveolar blood vessels
Increased resistance of alveolar vessels occurs during
Inspiration
Increased resistance of extra-alveolar blood vessels occurs during
Expiration
If decreased O2 in blood and vasoconstriction are maintained over a period of time, this can result in
COPD
