Pulmonary Blood Flow Flashcards
What tells you that the pulmonary pressure is very low?
The walls are very thin and there is not very much smooth muscle
What is the pressure within the pulmonary arterioles?
25/8 mmHg or 15mmHg mean
Why is there no smooth muscle in the pulmonary system?
Unlike systemic circulation, all of the blood goes to one place, the lungs.
How do horses get EIPH?
The capillary pressure in the pulmonary systems get too high and they burst
What is transmural pressure?
The difference between the capillary lumen and alveolar pressure
What is radial traction?
The parenchyma around the vessels can exert a force on the arteries and veins and widen them at moderate lung volumes and lower the PVR. At very high lung volumes however, it can cause them to stretch out which increases the PVR
How do capillaries distend or collapse?
The walls of the alveolar epithelium are so small that it is considered to just be surrounded by gas. The pressure in the alveoli are able to distend or collapse the capillaries
How do you calculate pulmonary vascular resistance?
Pulmonary arterial pressure- (LA/Q)
What happens to PVR during exercise?
- PVP increases and recruits more pa, pv, and pc
- Distention of vessels already there (lower PVR)
- affected by the lung volumes
Why don’t you want to breath to your total lung capacity?
The forces on the vessels from the parenchyma is so high that it stretches the vessels in the lungs and greatly increases PVR
Why don’t you want to increase alveolar pressure too high?
It can collapse the capillaries and no blood flow will get through. Why you have to be careful with mechanical respirators
What is hypoxemic pulmonary vasoconstriction?
This is vasoconstriction due to an increase in O2 pressure. Low alveolar O2 levels causes the release of endothelin which causes great vasoconstriction and basically cuts off the circulation to the area with low O2 and causes high levels of CO2 in the airways affected.
Why do horses have a CaO2 that goes up during exercise?
Their spleen stores a large amount of blood that can be released during exercise. increase from 20mL to 26mL
What animals are most effected by HPV and why?
Cattle and pigs. They have very low interconnectivity of the lungs
Why is there higher blood flow in the dorsal lung of the horse?
Horses produce regulatory factors (NO) that preferentially vasodilate the dorsal part of the lungs
