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  • Hi there!

  • Can you guess what I am?

  • I'll give you a hint...

  • I have a very important job inside your body

  • and your heart helps me to do my job.

  • I'm a red blood cell!

  • My job is so important that you'll thank me for it later!

  • But I can't take all the credit.

  • Without your heart I couldn't do a thing!

  • You see, I'm like a little delivery truck in your body.

  • I pick up and drop things off all the time.

  • I ride the highways of something called

  • the circulatory system.

  • I like to call it the Circle System

  • because I keep going in circles!

  • This system is made of your heart and blood vessels

  • that carry your blood to different areas of your body.

  • Your blood vessels are like tiny tunnels

  • that run all through your body.

  • They are made up of arteries that take oxygen

  • to places in your body,

  • and veins that take carbon dioxide

  • from your body to your lungs.

  • This is MY highway.

  • But I can't move by myself.

  • I move within your blood when it moves.

  • How does your blood move, you ask?

  • Why, your heart pumps it.

  • Let me show you how.

  • Your heart is the most important muscle in your body.

  • It moves by itself and even though you can hardly feel it,

  • it keeps moving all the time,

  • even when you are sleeping.

  • Want to feel your heart move?

  • Sit very still and put your hand on your chest.

  • If you were running hard or exercising

  • you might find it easier to feel.

  • When your heart moves it's called a "heartbeat".

  • Your heart makes at least 100,000 heartbeats every day.

  • When your heart beats it pulls blood into it

  • and pushes it out again.

  • This helps the blood to move fast enough

  • to go through your whole body and back.

  • And it helps me to pick up my deliveries

  • and take them to different places in your body.

  • I'm not alone in there.

  • There are lots of red blood cells just like me

  • doing the same thing in your body all the time.

  • Even now, while I'm talking to you!

  • Here's me at the start of my little journey.

  • I just got back from dropping off some things

  • to some places in your body.

  • I need to get some more speed to do more deliveries

  • so I ride your bloodstream into your heart.

  • Going through the heart is easy because the heart

  • has special rooms and doors that only open one way.

  • Right now I am entering the right side of the heart.

  • I go through the first room called the "right atrium",

  • through the first door called the "tricuspid valve",

  • and through the second room called the "right ventricle",

  • and through the second door called the pulmonary valve.

  • The heartbeat causes the heart

  • to squeeze the blood in these rooms into the next area.

  • It pushes the blood through it and into the arteries

  • (like tunnels) that lead to other parts of the body.

  • So, now I'm moving a little faster

  • cause the heart has given me a push.

  • Now I need to go and pick up the things I need to deliver.

  • My first stop is to the lungs.

  • I need to pick up a little oxygen molecule

  • to take to someplace in the body.

  • Every body needs oxygen.

  • Our lungs bring it into our body,

  • and then I pick it up and take it to where it's needed.

  • It seems like it would be tricky to pick up the oxygen,

  • but the lungs really help me with that job.

  • You see, here in the body we all work together

  • and co-operate to keep everything running smoothly.

  • When I get to the lungs...

  • (I'm not really this big, it's just easier to see me this way)

  • ... and I get really close to the sides of my little tunnel...

  • ... the oxygen that is sort of floating out of the walls nearby

  • just jumps onto me for the ride.

  • When enough of it has hopped on and I can't hold anymore

  • then I'm ready to go back to the heart for another push.

  • Know what?

  • This all happens so fast that it's even faster than blinking!

  • So now this time I need to go in the other side of the heart.

  • This side is for all of us red blood cells

  • that are carrying oxygen.

  • The heart pushes us a little farther this time

  • because some of us have a very long trip.

  • I go in through the first room called the "left atrium"

  • through the "mitral valve" "doorway"

  • and into the "left ventricle" room to get my big push.

  • Then out I go and on my journey!

  • I like my job because I get to travel.

  • Here I am making a delivery in the foot area!

  • All I have to do is draw near to the tunnel wall

  • and the oxygen will just jump out of my truck

  • and squeeze out of the tunnel!

  • It's pretty neat to watch.

  • While this is happening I also make another pick-up.

  • Carbon dioxide needs to be taken up to the lungs

  • so that the body can get rid of it by breathing out.

  • And I'm just the cell to do it!

  • I grab some and off I go again.

  • Going back up to the heart is a little tricky

  • because I need to ride up.

  • It's kind of like climbing a hill.

  • Because of this the veins have little trap doors called valves

  • that only open one way.

  • This stops me from floating in the wrong direction.

  • So I keep going up and up as the heart

  • keeps beating and pushing the bloodstream along.

  • Eventually I get back to the heart again

  • where I get ready to drop off the carbon dioxide in the lungs

  • and get a good push to get me going on another pick-up.

  • So that's my job! What do you think?

  • Pretty important isn't it?

  • The heart really helps me to do my job well!

Hi there!

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A2 初級 美國腔

探索心臟--循環系統! (Exploring the Heart - The Circulatory System!)

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    jm117 發佈於 2021 年 01 月 14 日
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