Chemical digestion · 化学消化
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| chemical digestion/ˈkemɪkl daɪˈdʒestʃn/ | 化学消化 | huà xué xiāo huà |
| carbohydrases/ˌkɑːbəʊˈhaɪdreɪzɪz/ | 碳水化合物酶 | tàn shuǐ huà hé wù méi |
| amylase/ˈæmɪleɪz/ | 淀粉酶 | diàn fěn méi |
| proteases/ˈprəʊteɪsɪz/ | 蛋白酶 | dàn bái méi |
| lipases/ˈlɪpeɪsɪz/ | 脂肪酶 | zhī fáng méi |
| neutralises/ˈnjuːtrəlaɪzɪz/ | 中和 | zhōng hé |
Breaking food apart — chemically
- Physical digestion makes food smaller; chemical digestion 化学消化 breaks the big molecules into small, soluble ones the body can absorb.
- This is done by digestive enzymes.
分开食物——化学地
- 物理消化把食物弄得更小;化学消化(chemical digestion)把大分子分解成身体能吸收的小的、可溶的分子。
- 这由消化酶(digestive enzymes)完成。
Amylase digests: · 淀粉酶消化:
Amylase is a carbohydrase acting on starch. · 淀粉酶是一种作用于淀粉的碳水化合物酶。
Match each enzyme to what it digests. · 把每个酶匹配到它消化的东西。
Each enzyme acts on one type of food molecule. · 每个酶作用于一种类型的食物分子。
Lipase breaks fats down into: · 脂肪酶把脂肪分解成:
Lipase produces fatty acids and glycerol. · 脂肪酶产生脂肪酸和甘油。
Proteins are digested into ______ acids. · 蛋白质被消化成______酸。
Protease breaks protein into amino acids. · 蛋白酶把蛋白质分解成氨基酸。
The three enzyme groups
- Carbohydrases 碳水化合物酶 (e.g. amylase 淀粉酶): break carbohydrates → simple sugars.
- Proteases 蛋白酶: break proteins → amino acids.
- Lipases 脂肪酶: break fats → fatty acids and glycerol.
A tooth in section: enamel over dentine, a soft pulp, and a root held by cement
三组酶
- 碳水化合物酶(carbohydrases,例如淀粉酶):把碳水化合物分解 → 简单的糖。
- 蛋白酶(proteases):把蛋白质分解 → 氨基酸。
- 脂肪酶(lipases):把脂肪分解 → 脂肪酸和甘油。
一颗牙齿的剖面:牙釉质覆盖牙本质,一个软的牙髓,以及被牙骨质固定的牙根
How fast a digestive enzyme works · 消化酶的工作速率
Add more substrate and the reaction rate climbs, then levels off as every enzyme is busy — the same way amylase, protease and lipase break down food. · 加入更多底物,反应速率上升,然后在每个酶都忙碌时趋于平稳——淀粉酶、蛋白酶和脂肪酶分解食物正是如此。
Bile neutralises stomach acid so enzymes in the small intestine work at their optimum pH. · 胆汁中和胃酸,让小肠中的酶在它们的最适 pH 工作。
The small intestine is alkaline; bile raises the pH. · 小肠是碱性的;胆汁提高 pH。
Where they work
- Amylase (mouth and pancreas) digests starch.
- Protease (stomach, pancreas) digests protein.
- Lipase (pancreas) digests fat.
它们在哪里工作
- 淀粉酶(amylase,口和胰腺)消化淀粉。
- 蛋白酶(胃、胰腺)消化蛋白质。
- 脂肪酶(胰腺)消化脂肪。
Conditions matter
- The stomach is acidic (good for its protease); the small intestine is alkaline.
- Bile neutralises 中和 stomach acid so intestinal enzymes work at their optimum pH.
Worked example. Starch is digested by amylase into maltose, then into glucose — small enough to be absorbed into the blood. Big molecule in, small soluble molecule out.
条件很重要
- 胃是酸性的(对它的蛋白酶有利);小肠是碱性的。
- 胆汁中和(neutralises)胃酸,让肠道的酶在它们的最适 pH 工作。
例题。 淀粉被淀粉酶消化成麦芽糖,然后成葡萄糖——小到足以被吸收进血液。大分子进去,小的可溶分子出来。
You've got it
- carbohydrases → sugars; proteases → amino acids; lipases → fatty acids + glycerol
- amylase digests starch, protease digests protein, lipase digests fat
- enzymes need the right pH; bile neutralises stomach acid for the small intestine
你掌握了
- 碳水化合物酶 → 糖;蛋白酶 → 氨基酸;脂肪酶 → 脂肪酸 + 甘油
- 淀粉酶消化淀粉,蛋白酶消化蛋白质,脂肪酶消化脂肪
- 酶需要正确的 pH;胆汁中和胃酸供小肠用