| What is blood?
It's that red stuff that comes out of you when you get a cut, right?
But what is blood made of? There are 4 major things that make up
your blood: plasma, red blood cells, white blood cells and platelets.
Together, the red and white blood cells and platelets are called
formed elements because they each have a specific shape, or form.
Each part of your blood has its own very important job…
Plasma is the liquid part of your blood and makes up about
half of it. This is the part that carries the blood cells to all
the parts of your body. On it's own, it's sort of a pale yellow
color and is made up almost totally of water, about 90%. The rest
is made up of hundreds of other things such as food and nutrients
for your body and proteins, which help your body fight infection.
It also contains chemicals called hormones, which tell your body
when to grow and how much.
Red blood cells are the red part of your blood. They're
very small and shaped a little like donuts without a hole. They
carry oxygen to your body and remove carbon dioxide from it. They're
mostly made up of something called hemoglobin, which carries the
oxygen and gives them their red color. The cells also contain certain
chemicals that help them do their jobs better. Red blood cells only
live for about 3 months, but your body is always making new ones
in your bone marrow, the stuff that fills up the insides of your
bones.
White blood cells help keep you healthy by fighting infections
in your body and protecting it from anything harmful that it might
come in contact with. Most of these cells are round and colorless.
Some kinds of white blood cells kill bacteria, basically by eating
them. Other kinds make antibodies, which kill bacteria, viruses
and other invaders.
Platelets are the smallest of the formed elements. They
are shaped like disks and are what help you stop bleeding. When
you get a cut they rush to the spot and stick to each other to plug
up the hole. They form the scab that you see later when the cut
is healing.
Interesting facts:
There are 5 million red blood cells, 10 thousand white cells and
250 thousand platelets in a pinhead-size drop of blood
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