THE HEART
(How it works)

The heart is a 4chambered muscle that pumps blood to the body and has an electrical charge that stimulates the muscle to work by pumping blood to the rest of the body. The electrical charge the (sinoatrial node) keeps the heart beating with a constant rhythm like a metronome. A metronome is a tool that musicians use to keep a beat or rhythm to the music they are playing. It keeps the same rhythm all the time when it is set until you change the speed to either speed it up or slow it down. The continual beating of the heart and rhythm of the heart is forcing blood out of the heart to the rest of the body.

A chamber is like a room with walls. There are 2 sides a right and left side to a normal heart. There are 2upper chambers of the heart called the right atrium and the left atrium and there are 2 lower chambers of the heart called the right ventricle and left ventricle. Each chamber of the heart has a special job. The 2 upper chambers of the heart called the right atrium and the left atrium are the parts of the heart that are called the receiving chambers meaning they receive blood as the blood is recirculated or flows back to the heart from the body.
The 2 lower chambers of the heart called the right ventricle and the left ventricle are the pumping chambers of the heart. They push, force or squeeze blood out and away from the heart to the rest of the body.

The blood is a special component of the body. There are two kinds of blood. One kind of blood is called red blood that has oxygen in it and the other kind of blood is blue blood that has given off its oxygen to the rest of the body. There is really only one kind of blood that circulates in the body. The red blood when it goes to all the other parts of the body it drops off oxygen and then has to rush back to the lungs to pick up more oxygen and get its red color back. As the blood is going back to the lungs after it has given off the oxygen it has lost its red color and is now blue and it is called blue blood until it reaches the lungs again and refills with oxygen and turns red in color again.

The blood has a special component to it called hemoglobin. This substance called hemoglobin is what gives blood its red color. Hemoglobin is what picks up the oxygen and carries the oxygen in the blood cells to the rest of the body.

The upper chamber of the heart called the right atrium receives the blue blood without oxygen from the body. The other upper chamber of the heart called the left atrium receives the red oxygen filled blood from the lungs. Remember the lungs fill with oxygen as we breath in. So as we are breathing in we are always taking in oxygen to refill the lungs with oxygen to relay it to the blood.

The lower chamber of the heart called the right ventricle pumps the blue blood that is oxygen free to the lungs under pressure that is minimal but enough pressure to be measured.

The other lower chamber of the heart called the left ventricle pumps under pressure and forces the red oxygen filled blood to the body under high pressure that can be measured that would be the same if your blood pressure was take.

Within the normal heart the blue blood that has given off oxygen and the red blood that is filled with oxygen should never mix together. This would cause an imbalance in the heart between the two different bloods and could cause many problems over time such as blueness to the lips and fingernails, tiredness and other serious problems.

The blood should flow in a circle like fashion in only one direction that is away from the heart and then back to the heart to start the entire cycle around the body and back to the lungs to pick up oxygen and to the heart to start this over and over again as long as the heart is able to pump.

The right and left chambers of the heart are both separated by walls or partitions called septums. The septum is like a wall in a house that separates two rooms. If you put a hole in the wall and the hole is big enough you can get to the other room. If the hole is small you can see into the other room.

The top upper 2 chambers of the heart called the right and left atria are separated by a wall called the atrial septum or atrial wall. The two lower chambers of the heart called the ventricles are separated by a wall called the ventricular septum or ventricular wall.

The heart also has valves that allow the flow of blood, which should flow normally in only one direction. Think of it like the water faucet in the house that only allows water to go out of the faucet.

On the right side of the heart what separates the upper right atrium from the lower right ventricle is the tricuspid valve.
On the left side of the heart what separates the upper left atrium from the lower left ventricle is the mitral valve.

The tricuspid valve allows the blood to flow in one direction only from the top chamber of the right atrium to the bottom right ventricle.
The mitral valve allows the blood to flow in one direction only from the top chamber of the left atrium to the bottom left ventricle.

There are two other valves in the heart that control the direction of blood flow out of the heart in the lower right and lower left ventricles called the pulmonary valve and the aortic valve.

The pulmonary valve controls the blood flow of the blue oxygen free blood forward and out of the right ventricle to the lungs.
The aortic valve controls the blood flow oxygen filled red blood forward to the rest of the body.

There are 4 major blood vessels that are associated with the heart. They are the superior vena cava, the inferior vena cava, the pulmonary artery and the aorta.

There are 2blood vessels that are called intake vessels that carry blood from the body to the heart. The intake vessels carry blue blood that gave off oxygen to other parts of the body and now carrying blue blood to the right side of the heart called the vena cava.

One vessel from the upper body is called the superior (upper) vena cava and the other is called the inferior (below) vena cava and both of these vessels enter the upper chamber of the heart called the right atrium.

The 3rd major vessel is the main pulmonary artery that carries blue blood from the right ventricle (lower chamber) to the lungs
This pulmonary artery divides into a right and left branch to supply the right and left lung.

The left side of the heart receives red oxygen filled blood from the lung through the pulmonary veins.

The pulmonary veins enter the upper chamber of the left atrium. The outgoing vessel from the heart is called the aorta. The lower chamber the left ventricle pumps the red oxygenated blood to the body through the aorta the 4th major vessel.

Some basic things to remember about the heart and how it works.
The heart is a muscle.
The heart develops or forms during the first 2 months of development of the fetus.
The heart pumps about 1700 gallons of blood a day.
Veins carry blood back to the heart.
Arteries carry blood away from the heart.