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? [music] ?

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KIDS: Our World!

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EVAN: Globey, today we’re going
to talk about blood in outer
space. Muah ah ah ah!

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Okay, relax Globey. We’re not
going to show anything scary.

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We’re going to discuss the
effects outer space has on our
blood...

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or it might be more accurate to
say the effects gravity has on
our blood.

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Did you know that blood is a
suspension?

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A suspension is a mixture of
solid particles floating in a
liquid.

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Blood is actually made up of
liquid, called plasma, which

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is mostly water, red blood
cells and white blood cells.

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Blood does a lot of incredible
things for your body.

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It helps fight off infection.
It heals wounds, and it

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carries oxygen and other
nutrients all over your body,

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and it even helps get rid of
carbon dioxide and other

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wastes that our cells don’t
need.

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And of course we all know our
heart is what pumps our blood.

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First our heart pumps the blood
to our lungs, where it picks up
oxygen.

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Then the blood which is now
rich with oxygen is pumped to

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our legs, arms, and our
brain... everywhere!

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But have you ever thought about
how much work that is for your
heart?

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And what effect does gravity
have on your blood?

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If you toss something, like
this ball, in the air, what
happens?

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That’s right! Gravity pulls the
ball down to the ground.

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And gravity does the same thing
to your blood.

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When you stand up, gravity
pushes your blood down to your
feet.

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Then your heart and muscles
have to do the hard part of

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pushing the blood back towards
your heart so it can

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be reoxygenated and continue to
nourish your brain and your
body.

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But in outer space, astronauts
don’t feel the effect of
gravity.

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So what kind of effect does
that have on your heart and
blood?

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Let’s ask Dr. Kjell Lindgren,
who is a flight surgeon at

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the NASA Johnston Space Center
in Houston, Texas.

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DR. LINGDREN: A flight surgeon
is a medical doctor.

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With my other flight surgeon
colleagues, we help take care

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of astronaut crew members and
their families.

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EVAN: One of the things Dr.
Lindgren studies is called
“fluid shift.”

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This is something that happens
to the astronauts’

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blood volume when they get into
outer space and have to

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deal with the effects of not
having gravity.

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DR. LINDGREN: On Earth, the
heart and the muscles

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constantly have to push the
blood around the body against

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the effects of gravity.

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Gravity is constantly pulling
blood down towards the feet
when you stand up.

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The heart and the muscles have
to push the blood back

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up to the heart and up towards
the head so the brain

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and the organs are all getting
enough blood and oxygen.

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In space, you don’t feel the
effects of gravity.

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Everything is floating. The
heart actually doesn’t have to
work all that hard.

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But the body continues to push
all that blood up to the

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chest and and up towards the
head. So in space, astronauts

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actually feel what we call a
“fluid shift,”

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the movement of most of the
blood up away from the legs

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and into the chest and towards
the face.

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If you see pictures of
astronauts who have just gotten
into orbit,

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their faces might look a little
puffy.

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They might say that they feel a
little congested.

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If you look at their legs,
their legs look a little bit
skinnier because

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the blood has moved out of the
legs and into the chest and
face.

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EVAN: That’s right. The
astronauts feel like their

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heads have gotten congested and
their legs have gotten
skinnier.

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And you know what? They have...
because gravity isn’t

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pulling blood into the legs and
feet, which causes it to gather
in the chest and head.

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It’s kind of like hanging
upside down on the monkey bars.

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You start to feel stuffy and
congested because all of the

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blood is flowing to your head.

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Over time, the astronauts’
bodies sense the extra blood

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in the chest and heart and
cause the astronauts to use

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the bathroom more to get rid of
the extra fluid.

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This helps somewhat reduce the
puffiness in the face.

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But what do the astronauts have
to do to correct the

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blood volume before they return
to Earth?

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DR. LINDGREN: The space
medicine community had been

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looking at fluid shifts and the
problems associated with

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fluid shifts from the very
beginning of the space program.

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We use counter measures or
techniques to try and avoid

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the effects of the fluid shift.
When astronauts return to the
earth,

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if they don’t have enough blood
volume and they stand

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up and their hearts and brains
aren’t getting enough blood,
you might pass out.

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So, we want to avoid that
obviously and keep our
astronauts healthy.

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We have various techniques to
do that. We have G suits

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which are the same things that
pilots wear when they’re

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flying fighter aircraft that
compress against the calves

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and thighs to push blood up to
the chest, the heart, and the
head.

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We have astronauts drink fluids
before they return to

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earth increase their blood
volume and we have various

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other techniques that can help
prevent the effects felt by
fluid shift.

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EVAN: The astronauts can also
do exercises which help to

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get the blood flowing through
the body.

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So Globey, today we learned
about the tremendous effect

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gravity can have on the blood
flow in your body.

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There are so many things the
astronauts have to be aware of
when traveling into space.

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Thank goodness with have
skilled doctors like

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Dr. Lindgren to look out for
them.

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? [music] ?

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KIDS: Our World!