So recall that there are four chambers in the heart.
The features of these chambers include two superior
atria which are our receiving chambers of the heart,
two inferior ventricles which are our
pumping chambers of the heart.
There are also several thickened
walls known as septa in the heart.
We had the interatrial septa which are
going to separate the atria in the heart
and in between these, we also have an
indentation known as the fossa ovalis.
This is a remnant of the foramen
ovale of the fetal heart which is a shunt
that allows for blood to go from
the right atrium to the left atrium,
skipping the lungs in the fetus
since fetuses are not using their lung.
This foramen is going to close at
birth and become the fossa ovalis.
We also have the interventricular septum which is
going to separate the left and the right ventricle.
So starting with our receiving chambers, we noticed
that the atria are small, thin-walled chambers
that are going to contribute actually
very little to the propulsion of blood
Within these chambers, we have the auricles which are
appendages that increase the volume of the atria.
The left atrium of the heart is going to receive oxygenated
blood that is returning to the heart from the lungs.
There are four pulmonary veins that are going
to feed into this left atrium from the lungs.
The right atrium of the heart is going to receive deoxygenated
blood that is returning to the heart from the body's tissues.
There are three main veins
that empty into this right atrium.
We have the superior vena cava which is going to
be returning blood from regions above the diaphragm,
the inferior vena cava which is going to be returning
blood to the heart from regions below the diaphragm
and then we have the coronary sinus which is going
to be returning blood from the coronary veins
in our coronary circulation.
So the next chambers are our discharging
chambers are pumping chambers.
These are referred to as ventricles.
These are going to have much
thicker walls than that of the atria.
and the reason why is because these are going
to be involved in the actual pumping of the heart.
The ventricles also make up
most of the volume of our heart.
The right ventricle is going to be
on the anterior surface of the heart.
It's going to be pumping blood into the
pulmonary circuit by way of the pulmonary trunk.
The left ventricle is located on the
posteroinferior surface of the heart
and it's going to pump blood into the aorta.
The aorta is the largest artery in the body
and is going to be responsible for pumping blood
to the rest of the body's tissues
by way of the systemic circuit.
Within these ventricles, we have
structures known as the trabeculae carneae.
These are irregular ridges of
muscles on the ventricular walls.
Also, we have the papillary muscles
which project into the ventricular cavity
and are anchored by these little
chords known as chordae tendineae.
These are going to be
attached to the heart's valves.