The Heart and Blood Circulation
The heart is a four chambered muscular pump around the size of a fist.
It beats about 100,000 times a day pumping around 2,000 gallons of
blood through about 100,000 miles of organic tubing.
The heart is a big muscle with four valves connected together to make
a two-stage pump. The heart gets its energy by oxidizing blood sugars.
This released energy, contracts the heart’s many muscle cells, and the
four chambers squeeze blood out into the arteries.
The arteries are thick walled muscular tubes which carry blood away
from the heart. The heart has two sides - the left ventricle and the
right ventricle. The artery from the right ventricle pumps blood to
the lungs, this is called the pulmonary artery and it is the only
artery that carries deoxygenated blood. The artery from the left
ventricle pumps blood to the rest of the body and it is called the
Veins are thin walled tubes which carry blood back to the heart, they
have a large diameter and valves. The veins returning blood from the
body are called the venae cavae. The vein from the lungs is called the
pulmonary vein and is the only vein to carry oxygenated blood.
The venae cavae collects oxygen depleted blood from the body and
routes the blood to the right atrium in the heart. When the right
atrium squeezes, it pushes blood through the tricuspid valve into the
right ventricle. Like the other three heart valves this is a one way
valve (blood can only flow in one direction). When the right ventricle
contracts, it pushes blood through the pulmonary valve and on into the
lungs. Because it does not take much pressure to get blood to the
lungs and back, the right side is smaller than the left. The left side
has to work...