Ventillation and blood flow Flashcards
what happens to blood flow when the blood pressure gets too low?
the pulmonary capillaries are collapsible herefore if pressure gets too low then the capillaries will collapse, closing off the blood supply
this will divert blood flow to capillary beds in which blood pressure is higher
what part of the lung has a low hydrostatic pressure at rest?
the apex
This causes some capillaries to collapse at rest
where is hydrostatic pressure greatest in the lungs and why?
the base due to gravity
How does the body match blood flow with airflow in each section of the lung?
by regulating the diameter of the arterioles and bronchioles
what is bronchiolar diameter mediated by?
C02 levels
if c02 levels on expired air increases then bronchioles dilate
if c02 levels on expired air decrease then bronchioles constrict
what is the autonomic control of pulmonary blood flow?
there is no neural control of pulmonary blood flow
there is little innervation of the pulmonary arterioles
what is blood flow in the pulmonary arterioles regulated by?
the oxygen content of the interstitial fluid around the arteriole
if the p02 in that area decreases then the arterioles respond by constricting- this diverts blood away from poor ventilated areas of the lung to better ventilated parts.
what is the difference between the action of the artioles in the pulmonary circulation compared to the systemic circulation in response to 02?
pulmonary arterioles constrict in response to low pa02
systemic arterioles dilate in response to low pa02
In the lungs, where is ventilation greatest?
Ventilation is greatest at the base
In the lungs where is compliance greatest?
Compliance is greatest at the base due to the alveoli at the base having all the air squeezed out due to the compression from the weight of the lung and the diaphragm, whereas the apex of the lung still has a high functional residual capacity.
