hi let's talk about the differences between bronchial and pulmonary arteries
in this video we'll discuss pulmonary versus bronchial vasculature to understand pulmonary
versus bronchial vasculature we need to understand the fundamental difference between the pulmonary
and systemic circuits you might call them circuits circulations or loops they all mean the same thing
the pulmonary circuit is the series of vessels which serve the alveolar capillaries the major
function here is gas exchange in the alveoli this circuit begins in the right ventricle of the heart
blood leaves through the pulmonary valve through the pulmonary trunk out through pulmonary arteries
eventually to the alveolar capillary beds where gas is exchanged and richly
oxygenated blood returns to the left atrium of the heart via pulmonary veins so in this
circuit pulmonary arteries carry deoxygenated blood and pulmonary veins carry oxygenated blood
we can contrast that with systemic circulation which begins in the left ventricle
of the heart blood is pumped out through the aortic valve through the main conduit the aorta
that blood is returned back to the heart after supplying metabolically active tissues of the body
with oxygen for chemiosmosis via the cable system so there is an inferior vena cavae
and a superior vena cava that return that blood to the right atrium let's take a look at this in
a little more detail so the pulmonary loop begins in the right ventricle here we are
our right ventricle 100 of cardiac output is leaving the right ventricle and heading out
through the pulmonary trunk to the pulmonary arteries which then serve capillary beds
around the alveoli of the lungs blood is then returned through four major pulmonary veins
to the left atrium we can also see here an interesting vascular novelty that's the
ligamentum arteriosum which is a remnant of the ductus arteriosus which in fetal circulation is
going to conduct relatively oxygenated blood from the pulmonary trunk in the vicinity of
the origin of the left pulmonary artery out to the arch of the aorta so this is a bypass
of pulmonary circulation in utero we can also see examples of pulmonary arteries
and pulmonary veins these pulmonary veins return that blood to the left atrium
which is deep here to the base of the heart
the key point is that these pulmonary arteries and veins are serving alveolar capillaries
this is 100% of cardiac output everything that's leaving the right ventricle
is going through these capillaries in terms of the pulmonary arteries
we can see them here and here they have a very very close association with the bronchi
those pulmonary arteries and their branches are going to mirror the tracheobronchial tree
on the other side of the alveolar capillary beds there are going to be tributaries that
coalesce into pulmonary veins these pulmonary veins are hyper variable
but ultimately they're going to coalesce into a superior and an inferior pulmonary vein in each
lung this tributary system will be completely independent of the pulmonary artery branches
it will be completely independent of the tracheobronchial tree in fact we'll see
tributaries into these veins both from within and between different bronchopulmonary segments
so there is no fidelity here between the pulmonary veins and the bronchopulmonary segments or
the conductive system that supplies them we can contrast that with the bronchial arteries
bronchial arteries are a part of the systemic circuit
that systemic circuit serves all of the metabolically active tissues
in the body um its main conduit is the aorta the aorta has a descending aorta
that follows the arch of the aorta that has two parts a thoracic and an abdominal part
the thoracic part of that descending aorta is what we'll be focusing on throughout this block
there are both visceral branches and parietal branches we've already discussed some of the
parietal branches so the posterior intercostal arteries those posterior intercostal arteries
leave the thoracic part to supply the intercostal spaces with blood
and from the thoracic part we'll have posterior intercostal arteries 3 through 11.
there are also various visceral branches and we'll discuss most of these in the
context of the posterior mediastinum but now we'll discuss the bronchial arteries
these bronchial arteries are going to supply the bronchi as per their name as well as the
lung connective tissue or stroma with blood they never reach the alveolar capillary beds these
terminate near but not at the respiratory bronchioles so they strictly supply the
conductive portions of the the respiratory pathway they also are going to supply regions
of the esophagus that are near as well as the roots of the lung so there's going to be broncho
pulmonary lymph nodes also known as hylar nodes that they supply these bronchial
arteries are tiny they're going to receive at maximum two percent of total cardiac output
their blood interestingly enough is largely returned via the pulmonary
veins of the pulmonary circuit some of that blood also is going to be returned via
bronchial veins and those bronchial veins drain into the azages system
these brachial arteries are quite variable the typical pattern
is that we will have two left bronchial
arteries that arise directly from the thoracic part of the aorta in the vicinity of the third
posterior intercostal arteries there's also typically only one right bronchial artery
that right bronchial artery is most likely to originate from the right third posterior
intercostal artery but it may also arise from the left superior bronchial artery
it then would be most likely to arise from the left inferior bronchial artery but it might also
arise from another right posterior intercostal artery or even be a branch of the thoracic aorta
so we've discussed the differences between pulmonary and systemic circulation
and the pulmonary vasculature which is of the pulmonary circuit and the bronchial
arteries which are of systemic circulation this is your summary slide thank you for your time