Human Physiology
人體生理學
How does your body stay alive? In this lesson you will learn how your circulatory, respiratory and digestive systems work to carry blood, air and food around your body.
你的身體怎樣維持生命？在這一課，你會學習循環、呼吸和消化系統怎樣把血液、空氣和食物運送到全身。
1 · The circulatory system
循環系統
The circulatory system carries blood around your body. The heart pumps blood through blood vessels. Arteries carry blood away from the heart, and veins carry blood back to the heart. Blood carries oxygen and nutrients to your cells.
循環系統把血液運送到全身。心臟把血液泵過血管。動脈把血液帶離心臟，靜脈把血液帶回心臟。血液把氧氣和養分運送到細胞。
2 · The respiratory system
呼吸系統
The respiratory system helps you breathe. Air enters through your nose and goes down to your lungs. In the lungs, tiny air sacs called alveoli pass oxygen into the blood and take carbon dioxide out.
呼吸系統幫助你呼吸。空氣由鼻子進入，向下到達肺部。在肺部，稱為肺泡的微小氣囊把氧氣送入血液，並把二氧化碳帶出。
Oxygen goes in, carbon dioxide goes out — this is gas exchange.
氧氣進入，二氧化碳排出——這就是氣體交換。
3 · The digestive system
消化系統
The digestive system breaks down your food. Food is chewed in the mouth, then goes down to the stomach, where enzymes help digest it. The small intestine absorbs nutrients into the blood.
消化系統分解你的食物。食物在口中咀嚼，然後到達胃部，酶幫助消化。小腸把養分吸收到血液中。
4 · Quick check
小測驗