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Unit 19: Biology Part 2 Page 47 of 137

size of a sugar cube) has 4-6
million RBC’s. RBC’s are the most
common cells in blood. Every
second, 2-3 million new RBC’s are
produced. Unlike the other cells in
our body, RBC’s have no nucleus.

They do however, have a protein
called hemoglobin. In fact, RBC’s
are 95% hemoglobin.
Figure 21 – White blood cells
help keep us healthy by
destroying pathogens.

Some WBC’s create antibodies.
Antibodies destroy pathogens.

The last thing that blood is made of
is platelets. Platelets are the part
of blood that helps with clotting. If
Figure 20 – Red blood cells are you have ever fallen down and
disc shaped cells with no scraped your knee, or received a
nucleus. small cut, it was the platelets that
helped stopped the bleeding.
Hemoglobin is the protein that Platelets can do this important job
carries oxygen. It also gives RBC’s because they are sticky little pieces
their red color. of cells.

White Blood Cells (WBC’s) are
larger than RBC’s, have a nucleus,
and do not have hemoglobin.
WBC’s only make up 1% of blood,
but still have a very important job
to do. These cells help keep us
healthy by seeking out and
destroying bacteria, viruses, and

pathogens, which are substances Figure 22 – Platelets are sticky
that can cause infection and pieces of cells that help in
disease. clotting.

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