messageds = new Array()
messageds[0] = null;
messageds[14] = "Superior vena cava:
returns blood from the
upper body to the heart."
messageds[13] = "Pulmonary valve:
stops blood flowing back
into the right ventricle."
messageds[12] = "Right atrium:
receives blood from the
vena cavae."
messageds[11] = "Tricuspid value (open):
when closed stops blood
flowing back into the right
atrium."
messageds[10] = "Right ventricle:
receives blood from the
right atrium. "
messageds[9] = "Cardiac muscle:
squeezes out blood during
the heart-beat. "
messageds[8] = "Inferior vena cava:
returns blood from the lower
body to the heart. "
messageds[1] = "Aorta:
carries blood to the body."
messageds[2] = "Pulmonary artery:
carries blood to the lungs."
messageds[3] = "Left atrium:
receives blood from the
pulmonary vein."
messageds[4] = "Pulmonary vein:
transports oxygenated blood
from lungs to the left
atrium."
messageds[6] = "Aortic value:
stops blood flowing back
into the left ventricle."
messageds[7] = "Left Ventricle:
receives blood from the left
atrium."
messageds[5] = "Mitral value
when closed, stops blood
flowing back into the
left atirum."
messageds[24] = "The heart
The heart is simply a bag of
muscle that - about once every
second-squeezes itself to
send blood flowing through
the body's network of blood
vessels. The heart has two
pumps, working side by side.
The left one sends blood out
along arteries to the whole
body, from head to toes. This
blood gives up oxygen and
returns along veins to the right
pump. From here it is sent on
a much shorter trip to the
lungs to gather more oxygen.
Two special features make
the heart incredibly hard-
working and versatile. The first
is the muscle in the heart's
walls. It is called cardiac
muscle and, unlike the normal
muscle, it never tires. The
second is the heart's ability to
change its pumping speed
and force to match the body's
needs. "