So now let's look at the pathway of
blood from the right side of a heart.
So on the right side of the heart, we have
three major veins that are going to come into
and meet with the right atrium.
These are the superior vena cava, the
inferior vena cava and the coronary sinus.
The superior vena cava is going to be
returning blood from above the diaphragm.
The inferior vena cava is going to be
returning blood from below the diaphragm
and the coronary sinus is going to be returning blood
from our coronary veins and coronary circulation.
From these veins, we go to the
next chamber which is the right atrium.
From the right atrium we go through the first
atrioventricular valve, this is the tricuspid valve.
From the tricuspid valve, blood is now
going to flow into the right ventricle.
Once in the right ventricle, it is now
going to be pumped out of that ventricle
into pulmonary circulation by way
of the pulmonary semilunar valve.
Once it travels through this valve it goes through
the pulmonary trunk to the pulmonary arteries
and eventually this blood is going to go to the
lungs where it will be oxygenated at the alveoli.
On the opposite side of the heart or the left
side of the heart, we have four pulmonary veins
that are going to feed into the left atrium of the heart.
Once in the left atrium, the blood will travel through
the mitral valve into the left ventricle of the heart.
When the left ventricle of the heart contracts, the blood
will be pumped out by way of the aortic semilunar valve
into the aorta where then it will
go through systemic circulation
delivering oxygenated blood to our body's tissues
so that our body may be able to use that oxygen
to undergo certain metabolic functions.
There are equal volumes of blood that are
going to be pumped through both circuits.
So we're gonna have an equal volume of blood pumped
to that lungs as well as to the rest of the body.
There are differences though and that
the pulmonary circuit is a shorter circuit
and it is a low pressure circulation.
The systemic circuit however is
much longer as it has to start at the heart
and pump throughout the whole
It is also a high friction circulation as it's
going to encounter a lot more resistance
than our pulmonary circuit which is shorter.
Because of this, the anatomy of the
ventricles is going to reflect this difference.
The left ventricle is responsible for
getting blood throughout the whole body
and therefore the walls of this ventricle are three
times thicker than the walls of the right ventricle.
This allows for the left vebtrivle to pump
blood with greater pressure or higher pressure
as compared to pulmonary which does not need
a lot of pressure to get the blood to the lungs.
You can see the differences between the left
ventricle and the right ventricle in this image.
Notice that the left ventricle is much
thicker than that of the right ventricle.
Again, this is because the left ventricle has the job
of pumping blood through a very high pressure system
that needs to get blood from
the heart to all parts of the body.
Whereas the right ventricle only needs to get
blood through the low pressure pulmonary circuit
which is right next to the heart in the lungs.