Red blood cells are manufactured in the bone marrow.
Blood makes up 7% of the weight of the body in humans. See: http://en.wikipedia.org/wiki/Blood
Your body makes more blood everyday.
It makes blood cells.
Bones
It makes blood cells.
The human body makes its own blood, it is impossible to synthesize.
You heart pumps the blood round
Heart.
the heart pumps the blood to different part of the body
That makes no sense!
the heart beating the blood around the body
Haemoglobin is the chemical in your body that makes your blood red.