Physiology 1 - Blood Supply, Gas Exchange, Ventilation and Perfusion Flashcards
Where is the ventilation and compliance of the lungs greatest?
Apex (declines from apex –> base)
Where do the lungs get their nutritional blood supply from?
Bronchial circulation
The pulmonary circulation is ____ flow, _____ resistance/pressure system
High
Low
What is the systolic BP in the lungs compared to the systemic circulation (120mmHg)?
25mmHg
Gas exchange at the alveoli occurs down what?
Partial pressure gradients
Rate of diffusion across a membrane is directly proportional to…
PP gradient
Gas solubility
Available SA
(inversely proportional tp thickness of membrane)
How is the PP gradient of O2 compared to CO2?
O2 10x greater than CO2 BUT CO2 more soluble in water so it diffuses faster than O2
Gases must enter what phase to dissolve into the blood?
Liquid
What features of the alveolar structure increase diffusion?
Very large SA
Thin membranes
Distribution of blood flow to the lungs is influenced by _______ and is proportional to _______.
Hydrostatic and alveolar pressure
Vascular pressure
How does the BF to the lung differ?
Apex - lowest BF as arterial pressure (less capillaries) < alveolar pressure (compresses arterioles and vascular resistance is increased)
Base - greatest BF as arterial pressure (more capillaries) > alveolar pressure (alveolar pressure (alveoli compressed by capillaries) so vascular resistance low
Where is there the greatest VQ mismatch in the lung?
A tthe base
What are the different types of VQ mismatch?
Mismatch 1 - V>Q ratio >1
Mismatch 2 - V
What autoregulation is done in the lungs to try to keep the VQ ratio as close to 1 as possible?
Shunting (when pulmonary BVs defect hypoxia, they vasoconstrict), increased PCO2 causes mild bronchodilation allowing better ventilation
What is alveolar dead space?
Space in lungs not participating in gas exchange due to lack of perfusion
