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The Heart and Circulatory System - How They Work

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 division

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 five quarts

of blood every minute and it beats about

100,000 times in one day that's about 35

million 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 for 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

heartbeat or about once every second

a beating heart contracts and relaxes

contraction is called systole and

relaxing is called diastole during

systole your ventricles contract forcing

blood into the vessels going to your

lungs and body much like ketchup being

forced out of a squeeze 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 to

blood vessels called coronary arteries

extend over the surface of your heart

and branch into smaller capillaries here

you can see just the network of blood

vessels that feed 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

rhythm which in turn keeps blood

circulating the continuous exchange of

oxygen-rich blood with oxygen-poor blood

is what keeps you alive