Unit7
指出英文
Stomach and small intestine
We humans do amazing things with food. Somewhere in the world,one person might eat only raw whale blubber in a given day,another might eat only rice,and still another miht eat only pizza and bananas,or drink dandelion wine.Through its metabolic magic,the human body converts the and a dizzying variety of other substances into usable energy and tissues of its own.validation
我们人类对食物做了许多神奇的事情。在世界上的某些地方，那里的人在特定的一天可能只吃生的鲸的脂肪，另外地方的人可能只吃米饭，仍然存在另一种人可能只吃披萨和香蕉，或是喝蒲公英酒。通过他（人体）的神奇的代谢过程，人体将这些物质以及其它多得令人眼花缭乱的东西转化成可用的能量和自身的组织。
Overview of the Digestive System(消化系统的概观）
A digestive system is a body cavity or tube in which food is reduced to particles, then to
molecules small enough to be absorbed into the internal environment.
消化系统是一个体腔或管，在那里食物被分解成颗粒，然后又变成小得可以吸入内环境的分子。
account numberSome invertebrates have an incomplete digestive system – a saclike gut with one opening. What goes in but cannot be digested goes out the same way.Most animals have a complete digestive system.This is a tube with an opening at one end for food intake and an opening at the other end for elimination of unabsorbed residues.The tube also has specialized regions for food transport, processing, and storage.etto
有些无脊椎动物有一个不完整的消化系统—一个有一个开口的囊状肠。进入系统但无法消化的东西从原路出来。大多数动物都有完全的消化系统。这是一条有一端开口摄取食物和另一端开口排出未被吸收的残留物的管。这条管也有专门的区域用作运输，处理，和储存粮食。
Stretched out, the digestive system of a human would extend 6.5 to 9 meters (21 to 30 f
eet).Its main regions are the mouth, pharynx, esophagus, and gut (gastrointestinal tract).The gut is subdivided into a stomach, small intestine, large intestine (colon), rectum, and anus.Salivary glands and a gallbladder, liver, and pancreas crete enzymes and other substances into different parts of the system.The overall functions of the system may be summarized this way:
1. Motility. Muscular movement of the system’s tubular walls. The movement leads to the mechanical reduction , mixing, and passage of food material, then elimination of undigested and unabsorbed residues.
2. Secretion. Relea of digestive enzymes, fluids, and other substances into the lumen (the space inside the digestive tube).
3. Digestion. Breakdown of food into particles, then into nutrient molecules small enough to be absorbed.
4. Absorption. Passage of digested nutrients, fluid, and ions across the tube wall and into the blood or lymph, which will distribute them through the body.
dialogue
如果拉伸出来，人的消化系统会达到6.5米至9米长（21到30英尺）。它的主要区域是口腔，咽，食道，肠（消化道）。肠道再细分为一个胃，小肠，大肠（结肠），直肠，肛门。唾液腺和胆囊，肝脏和胰腺分泌的酶和其他物质进入系统的不同部分。系统的整体功能可以用以下的方式概括：
1、蠕动。该系统的管壁的肌肉运动。（肌肉）运动导致食物的机械性分解、混合和通过，然后促成未消化和未吸收的残留物的排泄。
2、分泌。释放消化酶，液体，和其他物质进入管腔（消化管内部空间）。
3、消化。把食物分解成颗粒，然后分解成小得可 以被吸收的营养分子。
4、吸收。被吸收的营养物质，液体，和离子穿过管壁进入血液或淋巴，血液和淋巴把它们分发给全身。milk什么意思
The stomach
国际高中和普通高中有什么不同The stomach, a muscular, stretchable sac, has three main functions. First, it stores and
mixes food. Second, its cretions help dissolve and degrade food. Third, it helps control passage of food into the small intestine.
胃是一个肌肉发达的、有弹性的囊，主要有三个功能。首先，它存储（容纳）和混合食物。其次，它的分泌物可以帮助溶解，降解食物。第三，它有助于控制食物进入小肠。
Stomach Acidity. Epithelium loaded with glands lines the inside of the stomach wall. Each day, cells in that lining crete about two liters of hydrochloric acid (HCl), pepsinogens, mucus, and other substances.The substances make up gastric fluid (that is, the stomach's own fluid）. stomach acidity increas when the HCL parates into H+ and Cl-，and this helps dissolve bits of food to form a liquid mixture called chyme.The acidity kills many microorganisms prent in food. It may cau heartburn when gastric fluid from the stomach backs up into the esophagus.jindou
胃酸。布满了腺体的上皮位于胃壁内侧。每天，细胞在那内层分泌大约两公升的盐酸（HCl）、胃蛋白酶原、粘液、和其他物质。这些物质组成了胃液（就是胃自己的液体）。当盐酸分离成H+ 和 Cl-时，胃酸增多，这有助于溶解小块食物，以形成称为食糜的
液体混合物。胃酸杀死许多存在于食物中的微生物。当胃液从胃回流到食道时，可能会导致胃灼热。
In respon to the sight, aroma, and taste of food, the brain signals the cretory cells to step up activity. Also, when food enters the stomach, it distends the wall and activates receptors in the lining. This also leads to incread cretory activity.
