Nose鼻子
Hairs and mucus trap dust and germs. Breathing through your nose gives your lungs cleaner, warmer air.
鼻毛和鼻涕攔住灰塵與病菌。用鼻子呼吸，肺得到的空氣更乾淨、更溫暖。
The Human Body · Lesson 4 · 人體探索 第四課
How Does Air Get into Your Blood?空氣怎麼進到血液裡？
Every breath travels to hundreds of millions of tiny air sacs, where oxygen crosses into your blood. Breathe along with a 3D pair of lungs.
每一口氣都會走到幾億個小肺泡，氧氣在那裡進入血液；跟著 3D 的肺一起呼吸。
Big idea · 一句話看懂
Your lungs cannot pull in air by themselves. The diaphragm moves down, the chest gets bigger, and air rushes in.
肺自己不會吸氣；是橫膈膜往下移、胸腔變大，空氣才湧進來。
3D Model · 3D 模型
Breathe Along with Your Lungs 跟著肺一起呼吸
Watch the diaphragm under the lungs: when it moves down and the ribs lift, the lungs fill. Press and hold Hold to breathe in while you take a real breath, and let go as you breathe out; the model breathes with you. The small window shows what happens inside one air sac. Press Count my breaths to give the model your own breathing rate.
看肺底下的橫膈膜：它往下移、肋骨往上抬，肺就鼓起來。真的吸一口氣時按住「按住吸氣」，吐氣時放開，模型就跟著你呼吸。旁邊的小窗顯示一個肺泡裡發生的事。按「數我的呼吸」，讓模型改用你自己的呼吸節奏。
Loading the chest… · 胸腔載入中…
Drag to turn · 拖曳旋轉 Scroll or pinch to zoom · 滾輪／雙指縮放
This 3D model needs WebGL, which this browser does not support. The cards below still explain everything.
這個瀏覽器不支援 WebGL，無法顯示 3D 模型；下方的卡片一樣能看懂。
Inside one air sac · 一個肺泡裡
Oxygen into the blood · 氧氣進入血液
Carbon dioxide out · 二氧化碳出來
- Breaths a day · 每天呼吸
- Air a minute · 每分鐘換氣
- L
- Air a day · 每天換氣
- L
- Oxygen in → out · 氧氣吸進→吐出
- 21% → 16%
About 0.5 L per quiet breath for an adult; deeper when you exercise. · 以成人安靜時每口約 0.5 公升計算；運動時會更深。
- Red-brown dome: the diaphragm, the main breathing muscle
紅褐色圓頂：橫膈膜，最主要的呼吸肌 - Light blue dots: fresh air coming in
淡藍色的點：吸進來的新鮮空氣 - Yellow dots: air going out, with more carbon dioxide
黃色的點：吐出去的空氣，二氧化碳比較多 - Cream tubes: the airways, branching like an upside-down tree
米色管子：氣管與支氣管，像一棵倒過來的樹
The ribs, breastbone, and spine are real, from the same BodyParts3D skeleton as Lesson 1. The lungs, airways, diaphragm, and heart are simplified drawings: real airways branch more than 20 times, not 6, and real air sacs are far too small to see.
肋骨、胸骨和脊椎是真實的，和第一課同一副 BodyParts3D 骨架。肺、氣管、橫膈膜和心臟是簡化的示意圖：真實的氣管會分岔 20 多次，不是 6 次；真正的肺泡也小到肉眼看不見。
Bone models: BodyParts3D, © The Database Center for Life Science, licensed under CC BY 4.0. We selected the bones, simplified the shapes, and turned the model upright; the lungs, airways, diaphragm, and heart are our own drawing. · 骨骼模型來源：BodyParts3D（日本生命科學資料庫中心，CC BY 4.0 授權）；本站挑選骨頭、簡化形狀並轉正方向，肺、氣管、橫膈膜與心臟為本站自繪示意。
Reading · 英文閱讀
4
Unit 4: How Does Air Get into Your Blood?
Put one hand on your belly and take a slow, deep breath. You probably felt your belly push out. You breathe more than 20,000 times a day, usually without thinking about it at all. A person can live for weeks without food and for days without water, but only a few minutes without air. Every one of your cells needs a steady supply of oxygen, and your lungs are where your body gets it.
一手放在肚子上，慢慢深吸一口氣。你大概會感覺到肚子往外鼓。你一天呼吸兩萬多次，通常完全沒在想它。人可以好幾個星期不吃東西、好幾天不喝水，卻只能撐幾分鐘不呼吸。你的每一個細胞都需要源源不絕的氧氣，而肺就是身體取得氧氣的地方。
Here is the surprise: your lungs cannot pull in air by themselves. They have no muscles of their own. The work is done by the diaphragm, a dome-shaped sheet of muscle under your lungs. When you breathe in, the diaphragm tightens and flattens, moving down, while small muscles between your ribs lift the ribs up and out. Your chest gets bigger, the air pressure inside your lungs drops, and air rushes in to fill the space. When you breathe out quietly, the diaphragm relaxes and domes back up, and your stretchy lungs spring back, like a balloon letting go of its air. The hand on your belly moved because the diaphragm pushed down on everything below it.
令人意外的是：肺自己不會吸氣，它們沒有自己的肌肉。真正在工作的是橫膈膜——肺底下一片圓頂形的肌肉。吸氣時，橫膈膜收縮變平、往下移，同時肋骨之間的小肌肉把肋骨往上、往外抬。胸腔變大，肺裡的氣壓下降，空氣就湧進來填滿空間。安靜吐氣時，橫膈膜放鬆、彈回圓頂，有彈性的肺也縮回去，就像氣球把氣放掉一樣。放在肚子上的手會動，是因為橫膈膜往下壓到它下面所有的器官。
Air takes a long trip to get to your blood. It enters through your nose, where tiny hairs and sticky mucus catch dust, and where the air is warmed and made moist. It passes down your throat into the trachea, or windpipe, a tube held open by rings of cartilage that you can feel at the front of your neck. The trachea splits into two bronchi, one for each lung, and they split again and again, more than 20 times, into thousands of tiny tubes called bronchioles. Doctors call this the bronchial tree, because it looks like a tree turned upside down.
空氣要走一段很長的路才到得了血液。它從鼻子進來，鼻毛和黏黏的鼻涕會攔住灰塵，空氣也在這裡被加溫、變得濕潤。接著它經過喉嚨，進入氣管——一條靠著一圈圈軟骨撐開的管子，你在脖子前面就摸得到。氣管分成兩條支氣管，一邊一條，然後一分再分，分岔二十多次，變成成千上萬條細小的細支氣管。醫生把它叫做支氣管樹，因為它看起來就像一棵倒過來的樹。
At the very end of the smallest branches are the alveoli, tiny air sacs that grow in bunches like grapes. You have hundreds of millions of them. Spread flat, their surface would cover about the floor of a classroom. Each air sac is wrapped in a net of capillaries, and the walls between the air and the blood are thinner than a soap bubble. Oxygen slips across into the blood, and carbon dioxide slips out into the air sac. Then the heart, which you met in Lesson 3, carries the fresh, oxygen-rich blood to the rest of your body.
在最細的分支末端，是一串串像葡萄一樣的小氣囊，叫做肺泡。你有好幾億個肺泡；把它們的表面攤平，大約可以鋪滿一間教室的地板。每個肺泡外面都包著一層微血管網，空氣和血液之間的壁比肥皂泡還薄。氧氣從這裡滲進血液，二氧化碳則滲出來、進到肺泡裡。接著，第三課認識的心臟，就把新鮮、充滿氧氣的血送到全身。
The air you breathe in is about 21 percent oxygen. Surprisingly, the air you breathe out still has about 16 percent oxygen, but it carries about 100 times more carbon dioxide than it did coming in. Your cells use oxygen to release the energy stored in food, and carbon dioxide is what is left over. In fact, what makes you feel that you need to breathe is mostly a rise in carbon dioxide in your blood, which your brain keeps track of all the time. That is why you breathe faster and deeper when you run.
我們吸進去的空氣大約有 21% 是氧氣。出乎意料的是，吐出來的空氣仍然有大約 16% 的氧氣，但二氧化碳比吸進來時多了約 100 倍。細胞用氧氣把食物裡儲存的能量釋放出來，二氧化碳就是剩下的東西。其實，讓你覺得「需要呼吸」的，主要是血液裡的二氧化碳變多了，而大腦隨時都在監測它。這就是為什麼跑步時，你會呼吸得又快又深。
Most adults at rest breathe about 12 to 20 times a minute, and children breathe a little faster. Your lungs keep growing until you are about 20 years old, so the choices you make now matter. Smoke, whether from cigarettes, burning incense in a closed room, or polluted air, damages the delicate air sacs, while regular exercise strengthens the muscles that help you breathe. Now count your breaths for 30 seconds, and let the lungs in the model breathe with you.
大多數成人安靜時每分鐘呼吸 12 到 20 次，孩子稍微快一點。你的肺會一直長到大約 20 歲，所以現在的選擇很重要。煙——不論是香菸、在密閉房間裡燒香，或是污染的空氣——都會傷害脆弱的肺泡；規律運動則會讓幫助呼吸的肌肉更強壯。現在數一數你 30 秒呼吸幾次，讓模型裡的肺跟著你一起呼吸。
Read aloud · 課文朗讀
Questions · 閱讀理解
If the lungs have no muscles, what makes air come in when you breathe in?
The diaphragm tightens and moves down, and the muscles between the ribs lift the ribs up and out. The chest gets bigger, the pressure inside the lungs drops, and air rushes in.
What happens in the alveoli?
Oxygen passes from the air sacs into the blood in the capillaries around them, and carbon dioxide passes from the blood into the air sacs to be breathed out.
What makes you feel that you need to breathe faster when you run?
Mostly a rise in carbon dioxide in the blood, which the brain keeps track of. Working muscles make more carbon dioxide, so you breathe faster and deeper.
Words & Phrases · 生字及片語
lung(n.)肺Whales have huge lungs and can hold their breath for a long time.鯨魚有巨大的肺，可以憋氣很久。breathe(v.)呼吸Breathe in slowly through your nose.用鼻子慢慢吸氣。diaphragm(n.)橫膈膜Singers learn to control their diaphragm to hold long notes.歌手學習控制橫膈膜，來唱出長音。trachea(n.)氣管The trachea is also called the windpipe.氣管的英文也叫 windpipe。air sac(n.)肺泡；氣囊Each tiny air sac is wrapped in blood vessels.每一個小小的肺泡都包著血管。carbon dioxide(n.)二氧化碳Plants take in carbon dioxide and give off oxygen.植物吸收二氧化碳，釋放出氧氣。inhale(v.)吸入Inhale deeply before you dive into the pool.跳進泳池之前，先深深吸一口氣。exhale(v.)呼出Exhale slowly and let your shoulders relax.慢慢吐氣，讓肩膀放鬆。
Quick Check · 小測驗
1. Which muscle does most of the work when you breathe in?
2. Where does oxygen pass into the blood?
3. What does the nose do to the air you breathe in?
4. About how much oxygen is in the air you breathe out?
5. According to the reading, why do people call the airways a tree?
The Path of a Breath · 一口氣的旅程
From your nose to your blood 從鼻子到血液
On its way from the tip of your nose to an air sac, the air passes through more than 20 branchings, and the whole trip takes about as long as one breath in.
從鼻尖到肺泡，空氣一路要經過二十多次分岔，整趟旅程大約只要吸一口氣的時間。
Trachea氣管
The rings keep the tube open, like the ridges on a vacuum cleaner hose. Feel them gently below your Adam's apple.
軟骨環讓管子不會塌陷，就像吸塵器軟管上的一圈圈紋路。在喉結下方輕輕摸得到。
Bronchi and bronchioles支氣管與細支氣管
The right bronchus is shorter and steeper than the left, which is why a peanut that goes down the wrong way more often ends up in the right lung.
右支氣管比左邊短、比較陡，所以不小心吸進去的花生，比較常掉進右肺。
Alveoli肺泡
Walls thinner than a soap bubble, wrapped in capillaries. This is where oxygen crosses into the blood.
壁比肥皂泡還薄，外面包著微血管；氧氣就在這裡進入血液。
Into the blood進入血液
Oxygen-rich blood goes to the left side of the heart, which pumps it out to every cell in the body.
充滿氧氣的血回到左心，再被打到全身每一個細胞。
Measure Yourself · 親身測量
Count your breaths and breathe with the model 數一數呼吸，跟模型一起呼吸
Breathe normally; do not try to breathe faster or slower. It helps to have a partner count for you, because counting your own breaths tends to change them.
正常呼吸就好，不要刻意變快或變慢。請同伴幫你數會更準，因為自己數的時候，呼吸常常會不自覺地改變。
- 1Hand on belly · 手放肚子上Sit still with one hand on your belly and one on your chest. Which hand moves more when you breathe quietly?安靜坐好，一手放肚子、一手放胸口。安靜呼吸時，哪一隻手動得比較多？
- 30Count · 數一數Count how many times you breathe in during 30 seconds, then multiply by 2. The model does the math for you.數 30 秒內吸氣幾次，再乘以 2。模型會幫你算。
- 2Hold and let go · 按住、放開Press and hold the breathe-in button while you breathe in, and let go as you breathe out. Watch the diaphragm move with you.吸氣時按住「按住吸氣」，吐氣時放開，看橫膈膜跟著你動。
Myth vs. Fact · 常見迷思
Four things people get wrong 四個常見的誤會
✗ Myth · 迷思Your lungs suck in air by themselves.肺會自己把空氣吸進來。
✓ Fact · 事實Lungs have no muscles to do that. The diaphragm and the muscles between your ribs make the chest bigger, and the air rushes in on its own.肺沒有能做這件事的肌肉；是橫膈膜和肋間肌把胸腔撐大，空氣才自己湧進來。
✗ Myth · 迷思We breathe in oxygen and breathe out only carbon dioxide.我們吸進氧氣，吐出來的全是二氧化碳。
✓ Fact · 事實Breathed-out air is still about 16 percent oxygen and only about 4 percent carbon dioxide. That leftover oxygen is why rescue breaths can help someone who has stopped breathing.吐出來的空氣仍有約 16% 是氧氣，二氧化碳只有約 4%。正因為還剩下這些氧氣，人工呼吸才救得了停止呼吸的人。
✗ Myth · 迷思Your two lungs are exactly the same.左右兩片肺一模一樣。
✓ Fact · 事實The right lung has three sections, called lobes, and the left lung has two. The left one is a little smaller, with a notch that makes room for the heart.右肺分成三葉，左肺只有兩葉。左肺稍微小一點，還有一個凹口讓出位置給心臟。
✗ Myth · 迷思We yawn because our body needs more oxygen.打哈欠是因為身體缺氧。
✓ Fact · 事實Scientists are still studying why we yawn. In experiments, people who breathed extra oxygen yawned just as often, so a lack of oxygen is probably not the reason.科學家還在研究人為什麼會打哈欠。實驗中，多吸氧氣的人打哈欠的次數並沒有變少，所以缺氧大概不是原因。
Remember It · 記憶口訣
Breathing in a sentence 一句話記住呼吸
Diaphragm down, air in橫膈膜往下，空氣進來
Down and in, up and out. The diaphragm moves one way, and the air moves to match.
往下就吸進、往上就吐出：橫膈膜往哪邊動，空氣就跟著配合。
An upside-down tree一棵倒過來的樹
Trunk = trachea, big branches = bronchi, twigs = bronchioles, and the leaves = the alveoli, where the real work happens.
樹幹＝氣管，大樹枝＝支氣管，細枝＝細支氣管，葉子＝真正在工作的肺泡。
Right three, left two右三葉、左兩葉
The right lung has three lobes and the left has two, because the heart takes up room on the left.
右肺三葉、左肺兩葉，因為心臟在左邊占了位置。
In through the nose用鼻子吸氣
Your nose is a filter, a heater, and a humidifier all in one. Your mouth is none of them.
鼻子同時是濾網、暖氣和加濕器；嘴巴三樣都不是。
In Chinese · 中文怎麼說
Out-In: The Chinese Word for Breathing 「呼吸」是先呼、再吸
English says “breathe in and out,” but the Chinese word 呼吸 (hūxī) puts them the other way around: 呼 means to breathe out, and 吸 means to breathe in. The word 氣 (qì) means air and breath in everyday Chinese, as in 一口氣, “one breath,” and 深呼吸, “take a deep breath,” and it is also the qi of traditional Chinese medicine. The phrase 上氣不接下氣, “the upper breath does not meet the lower breath,” describes someone gasping for air after running.
英文說 breathe in and out（先吸再吐），中文的「呼吸」卻反過來：「呼」是吐氣，「吸」是吸氣。「氣」在日常中文裡就是空氣和氣息，例如「一口氣」「深呼吸」，也是中醫講的「氣」。「上氣不接下氣」則是形容跑完步喘不過氣的樣子。
Classroom Activity 1 · 課堂活動一
A Bottle-and-Balloon Lung Model 寶特瓶氣球肺模型
You need · 準備材料
- A small plastic bottle with the bottom cut off (an adult should do the cutting)一個剪掉底部的小寶特瓶（請大人剪）
- A small balloon (the lung)一顆小氣球（肺）
- A large balloon cut in half, or a piece of a rubber glove (the diaphragm)剪成一半的大氣球，或一片橡膠手套（橫膈膜）
- A rubber band and tape橡皮筋和膠帶
Steps · 步驟
- Push the small balloon into the bottle and stretch its mouth over the bottle's neck.把小氣球塞進瓶子裡，氣球口反套在瓶口上。
- Stretch the cut balloon or glove over the open bottom and hold it with the rubber band. Tie a knot or tape a tab in the middle to pull on.把剪開的氣球或手套撐開套住瓶底，用橡皮筋固定；在中間打個結或貼一小段膠帶當把手。
- Gently pull the bottom sheet down. What happens to the balloon inside?輕輕把底部的膜往下拉。裡面的氣球怎麼了？
- Let it go. What happens now? Which part of your body is the bottom sheet?放開。現在又怎麼了？瓶底那片膜代表身體的哪個部位？
Teaching tip: nobody blows into the balloon, yet it fills. That is the big idea of the lesson: the lungs are filled by the space around them getting bigger. Compare with the diaphragm in the 3D model.
教學提示：沒有人對著氣球吹氣，它卻鼓起來了——這正是本課的大觀念：肺是因為周圍的空間變大才被撐滿的。對照 3D 模型裡的橫膈膜看看。
Classroom Activity 2 · 課堂活動二
One Breath in a Balloon 一口氣吹氣球
You need · 準備材料
- A new balloon for each student (never share)每人一顆新氣球（不可共用）
- A tape measure or a piece of string and a ruler捲尺，或一條棉線加一把尺
- A worksheet學習單
Steps · 步驟
- Take a normal breath, then blow it all into the balloon in one go. Pinch it closed and measure around the widest part.正常吸一口氣，一口氣全部吹進氣球，捏住氣球口，量最寬處的圓周。
- Let the air out. Now take the deepest breath you can and blow it all in. Measure again.把氣放掉。這次盡量深吸一口氣，全部吹進去，再量一次。
- Compare the two numbers. How much bigger is a deep breath than a normal one?比較兩個數字：深呼吸比平常的一口氣大了多少？
- Discuss: when might your body need those deep breaths?討論：什麼時候身體會需要這麼深的呼吸？
Teaching tip: a quiet breath for an adult is about half a liter, and the deepest breath can be several liters. Stop anyone who feels dizzy, and check for latex allergies first.
教學提示：成人安靜時一口氣大約半公升，最深的一口氣可以到好幾公升。有人覺得頭暈就停下來；活動前先確認有沒有乳膠過敏。
⚕ Health note · 健康提醒This lesson is for learning about the body. It is not medical advice. If you have trouble breathing, your chest feels tight, or your lips look blue, tell an adult right away. Never play breath-holding games or breathe very fast on purpose; both can make people faint.本課是認識身體的教材，不是醫療建議。如果呼吸困難、胸口悶，或嘴唇發紫，請馬上告訴大人。不要玩憋氣比賽，也不要故意快速呼吸，兩者都可能讓人昏倒。