? [music] ?
KIDS: Our World!
EVAN: Globey, today we’re going to talk about blood in outer space. Muah ah ah ah!
Okay, relax Globey. We’re not going to show anything scary.
We’re going to discuss the effects outer space has on our blood...
or it might be more accurate to say the effects gravity has on our blood.
Did you know that blood is a suspension?
A suspension is a mixture of solid particles floating in a liquid.
Blood is actually made up of liquid, called plasma, which
is mostly water, red blood cells and white blood cells.
Blood does a lot of incredible things for your body.
It helps fight off infection. It heals wounds, and it
carries oxygen and other nutrients all over your body,
and it even helps get rid of carbon dioxide and other
wastes that our cells don’t need.
And of course we all know our heart is what pumps our blood.
First our heart pumps the blood to our lungs, where it picks up oxygen.
Then the blood which is now rich with oxygen is pumped to
our legs, arms, and our brain... everywhere!
But have you ever thought about how much work that is for your heart?
And what effect does gravity have on your blood?
If you toss something, like this ball, in the air, what happens?
That’s right! Gravity pulls the ball down to the ground.
And gravity does the same thing to your blood.
When you stand up, gravity pushes your blood down to your feet.
Then your heart and muscles have to do the hard part of
pushing the blood back towards your heart so it can
be reoxygenated and continue to nourish your brain and your body.
But in outer space, astronauts don’t feel the effect of gravity.
So what kind of effect does that have on your heart and blood?
Let’s ask Dr. Kjell Lindgren, who is a flight surgeon at
the NASA Johnston Space Center in Houston, Texas.
DR. LINGDREN: A flight surgeon is a medical doctor.
With my other flight surgeon colleagues, we help take care
of astronaut crew members and their families.
EVAN: One of the things Dr. Lindgren studies is called “fluid shift.”
This is something that happens to the astronauts’
blood volume when they get into outer space and have to
deal with the effects of not having gravity.
DR. LINDGREN: On Earth, the heart and the muscles
constantly have to push the blood around the body against
the effects of gravity.
Gravity is constantly pulling blood down towards the feet when you stand up.
The heart and the muscles have to push the blood back
up to the heart and up towards the head so the brain
and the organs are all getting enough blood and oxygen.
In space, you don’t feel the effects of gravity.
Everything is floating. The heart actually doesn’t have to work all that hard.
But the body continues to push all that blood up to the
chest and and up towards the head. So in space, astronauts
actually feel what we call a “fluid shift,”
the movement of most of the blood up away from the legs
and into the chest and towards the face.
If you see pictures of astronauts who have just gotten into orbit,
their faces might look a little puffy.
They might say that they feel a little congested.
If you look at their legs, their legs look a little bit skinnier because
the blood has moved out of the legs and into the chest and face.
EVAN: That’s right. The astronauts feel like their
heads have gotten congested and their legs have gotten skinnier.
And you know what? They have... because gravity isn’t
pulling blood into the legs and feet, which causes it to gather in the chest and head.
It’s kind of like hanging upside down on the monkey bars.
You start to feel stuffy and congested because all of the
blood is flowing to your head.
Over time, the astronauts’ bodies sense the extra blood
in the chest and heart and cause the astronauts to use
the bathroom more to get rid of the extra fluid.
This helps somewhat reduce the puffiness in the face.
But what do the astronauts have to do to correct the
blood volume before they return to Earth?
DR. LINDGREN: The space medicine community had been
looking at fluid shifts and the problems associated with
fluid shifts from the very beginning of the space program.
We use counter measures or techniques to try and avoid
the effects of the fluid shift. When astronauts return to the earth,
if they don’t have enough blood volume and they stand
up and their hearts and brains aren’t getting enough blood, you might pass out.
So, we want to avoid that obviously and keep our astronauts healthy.
We have various techniques to do that. We have G suits
which are the same things that pilots wear when they’re
flying fighter aircraft that compress against the calves
and thighs to push blood up to the chest, the heart, and the head.
We have astronauts drink fluids before they return to
earth increase their blood volume and we have various
other techniques that can help prevent the effects felt by fluid shift.
EVAN: The astronauts can also do exercises which help to
get the blood flowing through the body.
So Globey, today we learned about the tremendous effect
gravity can have on the blood flow in your body.
There are so many things the astronauts have to be aware of when traveling into space.
Thank goodness with have skilled doctors like
Dr. Lindgren to look out for them.
? [music] ?
KIDS: Our World!