Respiration: VQ Ventilation, Perfusion Relationships Flashcards
What does ‘Ventilation’ mean?
The process by which air moves IN and OUT of the lungs
What does ‘Perfusion’ mean?
The process by which deoxygenated blood passes through the lung and becomes oxygenated
What effect does gravity have on ventilation?
Air is not uniformly distributed in the lung
greater alveolar volume in apex (top)
what is pleural pressure P[pl]?
The pressure within the pleural cavity (in between chest wall and lung)
What is (physiological) dead space?
volume of inhaled air that doesnt take part in gas exchange (is in the airways or alveoli)
What are the types of dead space?
Anatomical dead space
Physiological dead space
What are the lungs blood supplys and what does each one do?
Pulmonary circulation: brings deoxygenated blood from heart to lung and oxygenated blood from lung to heart
Bronchial circulation: brings oxygenated blood to lung parenchyma/tissue
Pulmonary circulation is ____ pressure & ____ resistance system
LOW pressure
LOW resistance
24/9mmHg compared to systemic circulation 120/80mmHg
What is the V/Q ratio and what’s the value for a healthy individual?
The ratio of ventilation to blood flow (perfusion)
0.8 in a healthy lung
What happens when V/Q>1?
Ventilation exceeds perfusion
What happens when V/Q<1?
Perfusion exceeds ventilation
