Let's learn about the anatomy of the heart.
Your heart is an amazing organ.
Did you know your heart beats 100,000 times every day?
We can learn a lot about heart anatomy by tracing a drop of blood through the heart.
The superior and inferior vena cavae bring deoxygenated blood from the body to the heart.
Blood flows from the vena cavae to a chamber called the right atrium.
Blood flows from the right atrium to a larger chamber called the right ventricle.
The blood flows past a valve called the tricuspid valve.
This one way valve has 3 leaflets or cusps and keeps blood flowing in one direction toward
the ventricle.
Blood is then pumped out of the right ventricle into another vessel called the pulmonary trunk
and past a valve called the pulmonary valve one of 2 semilunar valves.
This one-way valve keeps the blood flowing toward the lungs.
Blood flows from the pulmonary trunk to the right and left pulmonary arteries.
An interesting fact is that these are the only arteries in the body that carry deoxygenated
blood.
Blood now moves into the lungs for oxygenation.
Oxygenated blood returns to the heart via the right and left pulmonary veins.
Most veins carry deoxygenated blood.
The pulmonary veins are an exception.
Blood enters the left atrium which is the receiving chamber on the left side of the
heart.
Blood flows from the left atrium to the left ventricle past the bicuspid or mitral valve.
Blood is pumped out of the left ventricle and enters the aorta while flowing past the
aortic valve, another one way semilunar valve.
Blood then moves through the arterial system to the body.
The heart is surrounded by a series of membranes called the pericardium or pericardial membranes.
Let's look at the layers of the heart and pericardium.
Looking from the inside out the endocardium is the innermost lining.
It consists of a thin layer of simple squamous cells.
The myocardium is a thick muscular layer consisting of cardiac muscle.
The visceral pericardium or epicaridium is the outermost layer of the heart.
The pericardial cavity is a space filled with a serous fluid called pericardial fluid.
The parietal pericardium is the fibrous outer most layer of the pericardium.
Looking at a bit more detailed diagram of the heart we can see the chordae tendinae
which are tendinous structures attaching the tricuspid and bicuspid valves to the papillary
muscles on the inner walls of the ventricles.
The papillary muscles are small muscles that contract when the ventricles contract to prevent
backflow of blood into the atria.
The fossa ovalis is a remnant of fetal circulation.
It begins in utero as the foramen ovale.
At birth a tissue flap closes the hole and it eventually permanently adheres and becomes
the fossa ovalis.
The trabecular carnae are muscular structures that line the walls of the ventricles.
The atria have similar structures called pectinate muscles.
The interventricular septum is a muscular wall between the ventricles.
The ligamentum arteriosum is another remnant of fetal circulation.
It begins as a tubular structure and after birth eventually becomes a ligament.
The top portion of the heart is known as the base.
The bottom portion is known as the apex.
Let's take a look at the coronary arteries.
These arteries supply the heart with blood.
There are 2 coronary arteries, the right and left.
Both originate from the aorta.
The right coronary artery supplies the right atrium and parts of both ventricles.
It branches to form the marginal and posterior descending.
The left coronary artery supplies the left atrium, left ventricle and interventricular
septum.
It branches to form the circumflex, marginal and anterior descending or interventricular
arteries.
We hope you have learned something about heart anatomy and see you next time.