🫁 呼吸系统：氧气的进站通道🫁 Respiratory System: the Oxygen Highway
上一片里，血液把氧气送到全身——可 🦠 小细胞要问：氧气是从哪儿进身体的？🩺 小医生带你走一遍这条进站通道。Last leaf, blood delivered oxygen all over the body — but Cellie asks: where does oxygen even get in? Dr. Doc walks you down this highway.
第 1 步：进站通道六站直达Step 1: Six stops to the lungs
先跟着一团氧气，从鼻孔走一遍全程。Follow one ball of oxygen all the way from the nostrils.
路线固定六站：鼻 → 咽 → 喉 → 气管 → 支气管 → 肺。咽是十字路口，空气和食物都从这过；喉口有会厌软骨当盖子；气管有软骨环撑着永不塌，再分成左右支气管进肺。鼻孔是安检口：鼻毛挡灰尘、黏液粘细菌，还顺手加温加湿——冷空气进来，暖湿空气出站。The route is fixed: nose → throat → voice box → windpipe → bronchi → lungs. The throat is a crossroads for both air and food; the voice box has the epiglottis as its lid; the windpipe is propped open by cartilage rings and splits into two bronchi. The nose is security: hairs and mucus trap dust and germs, while warming and humidifying the air — cold air in, warm moist air onward.
氧气自己不会走——是谁在“吸”它进来？Oxygen doesn't walk by itself — what sucks it in?
第 2 步：膈肌是一台活塞泵Step 2: The diaphragm is a piston pump
胸腔底部有一块穹顶形的肌肉，叫膈肌。吸气时它收缩压平，胸腔变大、气压变低，外面的大气压就把空气“压”进来；呼气时它放松回弹，胸腔变小，气体被挤出去。所以呼吸的主力不是“吸”，而是靠压强差——膈肌下降，空气自己冲进来。At the bottom of your chest sits a dome-shaped muscle: the diaphragm. When it contracts and flattens, the chest grows, pressure inside drops, and the outside atmosphere pushes air in. When it relaxes, the dome springs back up, the chest shrinks, and air is squeezed out. Breathing isn't really "sucking" — it's a pressure difference doing the work.
这条通道很耐用，但最怕一样东西。This highway is tough — but it fears one thing.
第 3 步：吸烟，给通道刷焦油Step 3: Smoking paints the highway with tar
气道内壁长着细小的纤毛，像刷子一样不停把灰尘细菌往外扫。烟雾里的焦油会把刷子粘住、让它们罢工，灰尘长驱直入；久而久之肺变黑变硬，弹性变差，咳喘找上门。好消息是：戒烟几天后，纤毛就开始修刷子了。Airway walls grow tiny hairs called cilia that sweep dust and germs outward like brushes. Tar in smoke glues the brushes down so they stop working, and grime marches in. Over time the lungs turn dark and stiff, and coughing and wheezing move in. The good news: within days of quitting, the cilia start repairing themselves.
🎮 你来当氧气导航员（30 秒）🎮 Your turn: oxygen guide duty (30 seconds)
🩺 小医生发来 4 团氧气的进站单，带它们从鼻走到肺——小心别把氧气导进食管！Dr. Doc hands you 4 oxygen manifests — guide each ball from nose to lungs, and don't route one down the food pipe!
一句话记住它：呼吸系统 = 氧气的进站通道：鼻做安检，膈肌当活塞压气进来，纤毛当保洁——吸烟会拆了这一切。Remember it in one line: the respiratory system is oxygen's highway — the nose checks tickets, the diaphragm pumps the piston, cilia keep it clean — and smoke wrecks it all.
路径六站：鼻 → 咽 → 喉 → 气管 → 支气管 → 肺；鼻子负责加温加湿过滤Six stops: nose → throat → voice box → windpipe → bronchi → lungs; the nose warms, humidifies and filters呼吸原理：膈肌下降 → 胸腔变大 → 气压变低 → 空气被压进来How it works: diaphragm drops → chest expands → pressure falls → air pushed in吞咽时会厌软骨盖住喉口——所以吃饭时不能同时呼吸；烟雾会让纤毛罢工Swallowing shuts the epiglottis over the airway — that's why you can't eat and breathe at once; smoke puts the cilia out of work
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
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