Not 2 arms, 2 eyes, or knees...
Not your legs,
Nor other part,
I never rest,
'Cause I’m your heart...
I pump away,
Each whole day!
Blood I'm pumping,
Through your veins,
Not one time,
Your heart's the part,
That keeps you fine...
|watch Mr. R.'s music video about the heart!
The heart is the organ which pumps blood throughout the circulatory system. All vertebrates have a heart, as do many invertebrates. The human heart is made up of cardiac muscle, which must keep working throughout your lifetime. The average human heart (based on a 78 year life span) beats about 3 billion times! But for all that work it does, the heart usually weighs less than a pound.
The human heart has four chambers, through which blood passes:
Deoxygenated blood enters the chamber called the right atrium.
The blood then moves to the next chamber called the right ventricle.
From the right ventricle the blood
passes through the pulmonary arteries to the lungs where it receives oxygen.
From the lungs, blood returns to the heart's left atrium and left ventricle.