Pulmonary circulation Flashcards
left side of the circulatory system?
high pressure
oxygenated blood
systemic circulation
right side of the circulatory system?
low pressure
deoxygenated
pulmonary (lungs only)
where does the lung tissue get its oxygen from?
respiratory zone of the bronchial tree - oxygen directly from gas exchange at air/blood interface
conducting zone?
thicker walled airways (trachea, bronchi, bronchioles) too thick for gas diffusion
blood supply for the lungs?
supplied by systemic circulation via the bronchial blood supply
bronchial vessels branch from?
from aorta
what do pulmonary vessels supply lung tissue with?
supply lung tissue with oxygenated blood
functions purely to supply the blood with oxygen from the lungs
bronchial circulation receives how much blood from the left ventricle?
receives 2% of the total output from the left ventricle
what does bronchial circulation supply?
supplies larger airways and interlobar septa
extrapulmonary airways supply goes where?
supply drains into the azygos vein (approx. 50% (1% of cardiac output))
extrapulmonary airways are?
large airways outside the lung parenchyma
conducting zone pulmonary airways supply drains via?
via bronchopulmonary anastomoses (remaining 50% (1% of cardiac output))
what is cardiac output?
the amount of blood that is pumped by the ventricles per minute
why does the heart vary its output?
it varies it according to an animal’s needs
cardiac output =
HR x SV
where does all the blood that is pumped through the right ventricle pass through?
it passes through the lungs
because all blood that is pumped through the right ventricle passes through the lungs - what does this mean?
means that cardiac output and lung perfusion are determined by the same factors
when cardiac output increases - lung perfusion increases, why does this happen?
since the left and right ventricle cannot beat independently of one another
pulmonary vessels respond to changes in?
cardiac output
pulmonary pressure of dogs, cats, sheep and goats?
all have low pulmonary pressures (the same as humans)
25/10 mmHg
pulmonary pressure of pigs, cows and horses?
all have higher pulmonary pressure
50/15 mmHg
what do pulmonary vessels do when blood flow through the lungs increases?
pulmonary vessels reduce their resistance
what does ability of blood flow depend on?
depends on the presence of smooth muscle in the walls of small pulmonary arteries
how do pulmonary vessels respond to small pressure increase?
the thin, flexible pulmonary vessels expand passively
what happens to capillaries that are closed during rest - when the blood flow increase?
they open (capillary recruitment)
which has the higher pressure: pulmonary arterial pressures or systemic pressures?
systemic pressure!
pulmonary arterial pressures are less than systemic pressures
what are alveolar vessels?
these are thin-walled capillaries that perfuse the alveolar septum
what are the alveolar vessels exposed to?
exposed directly to alveolar pressure changes (hence compress if this increases)
what are extra-alveolar vessels?
pulmonary arteries and veins
what do the extra-alveolar vessels accompany?
accompany bronchi in a connective tissue sheath
‘bronchovascular bundle’
the behaviour of the extra-alveolar vessels is determined by?
by pressure changes within the connective tissue space (parenchyma) of the bronchovascular bundle
when low oxygen? - ABERDEEN COWS IN ARGENTINA
closing vessels
increase resistance
pressure increases
pulmonary artery pressure increases
backs into right ventricle and then into right atrium
pressure backs up into vena cava
swelling
Bovine high mountain/Brisket disease
what is pulmonary vascular resistance?
PVR
it is the relationship between the pressure differential across the pulmonary circulation and the cardiac output (CO)
PVR = (equation)
difference in pressure / cardiac output
how do you find pulmonary pressure differential? difference in pressure?
pulmonary artery pressure - left atrial pressure
when is PVR low?
low at rest
where do the peribronchial plexus vessels lie?
they lie within the connective tissue along the airways
what do the branches of the peribronchial plexus supply?
they supply the subepithelial plexus
other than the subepithelial plexus, what does the peribronchial plexus supply?
also supply vaso vasorum (vessels of vessels)
what happens to the bronchopulmonary vessels at the alveoli?
extensive bronchopulmonary anastomoses at the level of the alveoli
what do pulmonary vessels respond to?
they respond to changes in CO
when do pulmonary vessels reduce their resistance?
when blood flow through the lungs increases
what does ability of blood flow depend on?
depends on the presence of smooth muscle in the walls of small pulmonary arteries
how do the pulmonary vessels respond when there is a small pressure increase?
it causes the thin, flexible pulmonary vessels to expand passively
pulmonary arterial pressures are less than what other pressure?
less than systemic pressures
what are alveolar vessels?
these are thin-walled capillaries that perfuse the alveolar septum
exposed directly to alveolar pressure changes (hence compress if this increases)
what are the extra-alveolar vessels?
pulmonary arteries and veins
accompany bronchi in a connective tissue sheath
what is the bronchovascular bundle?
it is the pulmonary arteries and veins which accompany bronchi in a connective tissue sheath
what is the behaviour of the extra-alveolar vessels?
behaviour is determined by pressure changes within the connective tissue space (parenchyma) of the bronchovascular bundle
