气体交换与呼吸
Gas Exchange & Breathing
描述人体气体交换系统（气管、支气管、细支气管、肺泡）的结构，并解释呼吸机制——肋骨和膈肌的运动引起压力变化——如何使空气进出肺部。
Describe the structure of the human gas exchange system (trachea, bronchi, bronchioles, alveoli) and explain how the mechanism of breathing — using pressure changes from rib and diaphragm movement — moves air in and out of the lungs
学习证据 / Evidence
- 标注肺部示意图，标出气管、支气管、细支气管和肺泡。
- 解释吸气时胸腔内气压降低，空气随之涌入。
- 描述肺泡的结构（表面积大、壁薄、血液供应充足）如何促进气体交换。
- Labels a diagram of the lungs showing trachea, bronchi, bronchioles, and alveoli
- Explains that breathing in lowers air pressure in the chest and air rushes in
- Describes how the structure of alveoli (large surface area, thin walls, good blood supply) aids gas exchange
评估问题 / Assessment
如果{{name}}在跑步后深吸一口气，能否解释肺里正在发生什么——空气是怎样进入的，氧气在哪里进入血液，二氧化碳又是怎样离开的？
If {{name}} took a deep breath after running, could they explain what's happening in their lungs — how the air gets in, where the oxygen crosses into the blood, and how carbon dioxide leaves?