Transcript for How the heart works

Your heart is a pump

It's a muscular organ about the size of your fist

and is located slightly left of center in your chest.

Your heart is divided into the right and left side.

The divison protects oxygen rich blood from mixing with oxygen poor blood

Together your heart and blood vessels comprise your cardiovascular system

which circulates blood and oxygen around your body.

In fact, your heart pumps about 5 quarts of blood every minute

and it beats about one hundred thousand times in one day.

That's about thirty five millon times in a year.

Oxygen poor blood, blue blood,

returns to the heart after circulating through your body.

The right side of the heart, composed of the right atrium and ventricle,

collects and pumps the blood to the lungs through the pulmonary arteries.

The lungs refresh the blood with a new supply of oxygen

making it turn red.

Oxygen rich blood, red blood, then enters the left side of the heart

composed of the left atrium and ventricle

and is pumped through the aorta to the body

to supply tissues with oxygen.

Four valves within your heart keep your blood moving the right way.

The tricuspid, mitral, pulmonary and aortic valves

work like gates on a fence:

They open only one way and only when pushed on.

Each valve opens and closes once per heart beat

or about once every second.

A beating heart contracts and relaxes.

Contraction is called Sytole and relaxing is called Diastole

During Systole your ventricles contract

Forcing blood into (the heart before) going to your lungs and body

much like ketchup being forced out of the squeezed bottle

The right ventricle contracts a little bit before the left ventricle does.

Your ventricles then relax during diastole

and are filled with blood coming from the upper chambers

the left and right atria.

Then the cycle starts over again

Your heart is nourished by blood too,

Blood vessels called coronary arteries

extend over the surface of your heart and branch into small capilaries

which fill your heart with oxygen rich blood

Your heart also has electrical wiring which keeps it beating.

Electrical impulses begin high in the right atrium

and travel through specialized pathways to the ventricles

delivering the signal to pump.

The conduction system keeps your heart beating in a coordinated and normal rythm

which in turn keeps blood circulating

The continuous exchange of oxygen rich blood with oxygen poor blood

is what keeps you alive.