hi let's discuss the differences between bronchial versus pulmonary circulation
in this video we'll discuss the differences between pulmonary and bronchial vasculature
so let's start with the pulmonary loop or pulmonary circulation pulmonary circulation
begins in the right ventricle that blood is sent through the pulmonary valve
to the pulmonary trunk that pulmonary trunk divides into right and left pulmonary arteries
those pulmonary arteries are going to follow the pathway of the tracheobronchial tree
out towards the alveoli and feed into capillary beds that surround the alva violi for the purposes
of gas exchange that blood is then returned back to the heart via pulmonary veins these
pulmonary veins are going to enter into the left atrium which we can see here in relation to the
base of the heart and then that blood is going to be sent along through systemic circulation
we also have a ligamentum arteriosum that ligamentum arteriosum can be seen
right here it's at the origin of the left pulmonary artery and it connects to the
concavity of the aorta and it's a remnant of the ductus arteriosus which is a fetal vascular
novelty that allows blood from the pulmonary trunk to be shunted directly to the
arch of the aorta so as a partial bypass of the pulmonary circulation in utero
these pulmonary vessels um are kind of the exception to the convention that you've probably
been thinking about blood and hopefully have been disabused of in the uh the cardiac sessions
and that being that pulmonary arteries while they conduct blood away from the heart
are carrying deoxygenated blood hence that is why i have color-coded them blue here
these pulmonary arteries tend to be in very close association with the primary bronchi at
the root of the lung or with as part of the root of the lung and they are going to mirror
that tracheobronchial tree as they go out to capillary beds surrounding the alveoli
the pulmonary veins i've color-coded here as red these are not in close association with that
tracheobronchial tree they have a tremendous amount of variation there is no fidelity to
bronchopulmonary segment so not only do they break free from the confines of the tracheobronchial
tree they also break free from the the confines of the uh the bronchopulmonary segments and so there
may be both intra and intersegmental tributaries of these pulmonary veins so there is one for
each lobe at least so we therefore have both a superior and an inferior pulmonary vein leaving
as part of the root of the lung the right lobe that has a or the right lung that has a middle
lobe will have a pulmonary vein associated with it that generally is associated with the superior
pulmonary vein on the right side so still four pulmonary veins a pair of superior and inferior
for each lung leaving the lung and conducting that oxygen-rich blood back to the heart now
when we think about volume these pulmonary vessels they are receiving 100 of the cardiac output so
everything coming from the right ventricle is is going through the this pulmonary circuit
we can contrast that with the bronchial arteries the bronchial arteries are going
to be branches typically of the thoracic part of the descending aorta so if we were to recall our
portions of the aorta we have the ascending aorta the arch of aorta and then the descending
aorta which has thoracic part which is everything superior to the diaphragm
and then below the diaphragm the abdominal part so that thoracic part is going to host typically um
two left bronchial arteries as we can see here and here or maybe if we pick a
a different color so we can see there and there so there's two left bronchial arteries and one
right bronchial artery that right bronchial artery let me erase this for the time being
is quite variable in its origin most typically it's a branch
of the right third posterior intercostal artery and here are the posterior intercostal arteries
recall that they are the dominant blood supply to the intercostal space
so that right bronchial artery can come off of that third right posterior intercostal artery
or it may be a branch of the superior of the two left bronchial arteries that's the
next most recent or it can come off of nearly any other artery in this vicinity
so there's there's there's quite a bit of variance here these bronchial arteries are going to supply
the tracheobronchial tree out to about the level of the respiratory bronchioles so
they don't make it to any capillary beds that surround alveoli so they don't participate in
gas exchange in that way so they're strictly there to supply the bronchi the tracheobronchial tree
as well as some of the connective tissue so some of the stroma of the lung with blood that blood
interestingly enough is generally returned into the pulmonary veins so that blood oftentimes is
shunted to the pulmonary loop after it's been oxygenated and then goes out through systemic
circulation so these bronchial arteries originate in systemic circulation and their
blood is returned venously back into that systemic circulation but on the arterial side it can also
return via the azigas system the aziga system will focus on when we discuss the posterior mediastinum
and that's a means by which the posterior lateral aspect of the thoracic cavity is drained of blood
so we've discussed the pulmonary loop or pulmonary circulation and its constituent vessels and volume
as well as the bronchial circulation coming from systemic circulation and returning back to
systemic circulation and only being a minute amount of blood that's you know maybe two percent
total of cardiac output of the blood that comes out of the left ventricle will go through these
uh these bronchial arteries maximum so this is your summary slide i thank you for your time