returns to the heart.
So let’s talk about the arteries. These
are the vessels that convey oxygenated blood
away from the heart – away from the left
ventricle – eventually to the body tissues
to the capillaries. They start out big and
they keep bifurcating or dividing into smaller
and smaller vessels, eventually the arterioles,
as they get further away from the heart until
eventually the arterioles connect to the capillaries
where the blood gives off its oxygen and nutrients
and collects waste products.
The circulation usually is drawn and with
the arterial system in red and the venous
system in blue.
The largest and most important blood vessel
in the body is the aorta. This is the large
blood vessel that leaves the heart just above
the aortic valve and supplies blood to each
of the branching arteries throughout the body.
And we’re going to be looking at each of
those branching arteries in a minute.
The first branches off the aorta are the coronary
arteries of course because the heart has to
have nourishment in order to keep pumping.
Then one arrives at a large right-sided vessel
called the right brachiocephalic artery which
divides into the right subclavian and the
right carotid. The right carotid goes up the
right side of the neck supplying blood to
the brain and the right subclavian supplies
blood to the arm. We then arrive at the left
carotid which supplies blood also to the brain
and then the left subclavian which supplies
blood to the left arm.
And here we see it in a little larger form.
First you see the right and left coronary
arteries coming off of the aorta just above
the aortic valve. Then you come to the brachiocephalic
which divides into the right subclavian and
the right common carotid. And then you see
the left common carotid and the left subclavian.
So that, by the time the blood starts to go
down into the descending aorta from the ascending
aorta, you’ve already supplied the brain
and you’ve supplied the arms and you’ve
supplied the heart. And, of course, there
are two carotids and two subclavians and only
one brachiocephalic because that branches
as I’ve just said into the right subclavian
and the right common carotid.
Here we see an anatomically-correct diagram
showing you blood vessels in the arm. And
you can see in red is the brachial artery,
which is a branch of the subclavian artery
as it comes down into the arm. This diagram
is right above the elbow. And you can see
that the veins run very close to the arteries
carrying blood back from the arm. There’s
two brachials and eventually, down below at
the wrist, we get into two radial arteries
and then two ulnar arteries, one on each side.
And then of course, there are the hand arteries
and we’ll be showing you this in a moment.
Down below in the abdomen you can see that
the aorta divides into a number of vessels
that supply the bowel. So there is two mesenteric
arteries – a superior and an inferior – and
they supply blood to the bowel so that the
bowel stays nourished and also so that we
can absorb digested food substances which
will be eventually delivered to all the cells
of the body as nutrition.
And of course another major branch off the
abdominal or lower aorta are the renal arteries
or the kidney arteries. And these, of course,
help to control the kidneys – our major
sources of blood-pressure control and also
fluid control. And we’ll be talking a lot
more about them later on in this series.
Finally we arrive down at the leg. The aorta
branches into two iliac arteries – one on
each side – and then into two femoral arteries
– one on each side – two popliteal arteries
– one on each side – and a number of smaller
foot arteries. So that on one side – let’s
say the left – you come down from the aorta.
The aorta branches into the iliac. Then the
iliac becomes two components of the femoral
artery, eventually, the popliteal artery,
which is right behind the knee, and then down
into the foot. And you can see here from this
diagram very clearly that the veins follow
the arteries in very, very close approximation.
Let’s talk a little bit about the capillaries
because, of course, that’s where the oxygen