Blood moves through my body
My blood carries oxygen to my cells.
Every cell in my body needs oxygen in order to live. Bone cells, muscle
cells, brain cells—all must have oxygen.
Every cell in my body gives off things my body cannot use, called
wastes. Bone cells, muscle cells, brain cells—all give off waste
materials.
My blood carries waste materials away from my cells. The waste materials
must be cleaned out of my blood. That happens as the blood passes
through my kidneys. My kidneys are behind my stomach near my spine.
The waste materials make a liquid in my kidneys. This liquid is called
urine. The urine flows down long tubes into my bladder. Another tube
leads from my bladder outside my body. Urine passes through this tube,
the urethra.
My body has between two and four quarts (2 and 4 liters) of blood. If I
cut myself and lose some, my body makes new blood to take its place.
Blood cells are made inside my bones. New ones are made every second. In
less time than it takes to count to two hundred, my bones can make more
than 100 million new cells for my blood.
This machine takes the place of a person’s kidneys. When someone’s
kidneys do not work as they should, the machine cleans waste products
from the person’s blood.
