Section outline

  • Lesson Objectives
    ::经验教训目标

    • Identify the major organs and general functions of the digestive system.
      ::确定消化系统的主要机构和一般功能。
    • Outline the digestive functions of the mouth, esophagus, and stomach.
      ::概括口腔、食道和胃的消化功能。
    • Explain how digestion and absorption occur in the small intestine.
      ::解释小肠中如何消化和吸收。

    Lesson Vocabulary
    ::词汇表课程

    • absorption
      ::匀支
    • chemical digestion
      ::化学消化
    • digestion
      ::消化
    • digestive system
      ::消化系统
    • elimination
      ::冲销
    • esophagus
      ::食道
    • large intestine
      ::大肠
    • mechanical digestion
      ::机械消化
    • nutrients
      ::营养养养
    • small intestine
      ::小肠
    • stomach
      ::肠胃

    Introduction
    ::导言

    Have you ever heard the saying, "You are what you eat?" It's true, our bodies take in food. All our energy comes from this food, but how? Our body breaks the food down into nutrients. These nutrients are the fuel that keeps our body running. Do you know how this works?  Read on to find out. 
    ::你曾没有听见吗?有人曾说过:你吃什么?不然,我们的身体就吃什么?我们的肉。我们所有的能量都是从这个食物中得来的,我们是怎样的呢?我们的身体把食物分解成营养物质。这些营养物质是维持我们身体运转的燃料,你们知道它是如何工作的吗?你们看看吧!你们看看吧!

    Food contains nutrients. These nutrients are needed by the cells of your body. How do they get from your sandwich to your cells? What organs and processes break down the food? How are these nutrients made available to cells? The answer is your digestive system. It is this system that controls the digestion and absorption of nutrients. Don't think it is that simple though. All the systems of your body work together to keep your body running at its best. 
    ::食物含有营养素。 这些营养素是您身体细胞需要的。 这些营养素如何从你的三明治到细胞? 什么器官和过程会分解食物? 这些营养素是如何提供给细胞的? 答案是你的消化系统。 这是控制消化和吸收营养素的系统。 虽然如此简单。 您身体的所有系统都会一起工作, 使身体保持最佳运转。

    The respiratory and circulatory systems work together. Together, they provide cells with the oxygen they need to operate. Cells also need glucose. Glucose is a simple sugar that comes from the food we eat. To get glucose from food,   must occur. Glucose is not the only thing we get from food. Our bodies also require proteins and fats. Let's learn a little about the digestive process. 
    ::呼吸和循环系统可以一起工作。 它们共同提供细胞需要的氧气。 细胞也需要葡萄糖。 葡萄糖是一种简单的糖, 它来自我们吃的食物。 要从食物中获取葡萄糖, 必须发生。 葡萄糖不是我们从食物中得到的唯一东西。 我们的身体也需要蛋白质和脂肪。 让我们来了解一下消化过程。

    Overview of the Digestive System
    ::消化系统概览

    The digestive system supports the body in three ways. First, it breaks down food. Second, it enables nutrients to be absorbed into the body. It is also responsible for the elimination of waste from the body. The major organs of the digestive system are shown in  Figure   . 
    ::消化系统以三种方式支持身体。 首先,它分解食物。 其次,它使养分能够吸收到身体中,它也负责消除身体中的废物。消化系统的主要器官见图。

     

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    Major organs of the digestive system make up the GI tract.
    ::消化系统的主要器官组成GI道

    The Digestive Tract
    ::消化轨迹

    The digestive system is essentially a long tube that passes through your body. Do you know how long your digestive tract is? Food enters the mouth and then travels more than 9 meters (30 feet). This distance is needed to process the food you eat. The food that is not digested is passed as waste.
    ::消化系统基本上是穿透身体的长管。 你知道消化道有多长吗? 食物进入嘴里,然后行走9米(30英尺)以上。 处理食物需要这条距离。 没有消化的食物是浪费的。

    The organs in the digestive tract are covered by a special type of muscle. These muscles contract to help move the food along. This muscle movement is like a wave through a spring toy. 
    ::消化道的器官被一种特殊的肌肉覆盖。这些肌肉合力帮助食物向前移动。这种肌肉运动就像一个波浪穿过一个弹簧玩具。

    Think about when you brush your teeth. You squeeze the toothpaste from the tube. The toothpaste moves out of the tube. This action is similar to how food is passed through your digestive tract. The diagram in  Figure    shows how this process works.
    ::想一想,当你刷牙时,你从管子上挤挤牙膏。牙膏从管子上移出来。这个动作与食物如何通过消化道相似。图中的图表显示了这个过程是如何运作的。

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    Peristalsis
    ::持久性

    Digestion
    ::文摘

    As food is pushed along, it undergoes digestion. Digestion is the process of breaking down food into nutrients. There are two types of digestion: mechanical digestion and chemical digestion.
    ::随着食物的推移,它会消化,消化过程是将食物分解成养分的过程,有两种消化方式:机械消化和化学消化。

    • Mechanical digestion occurs when large chunks are turned into smaller chucks. Perhaps not surprisingly, this happen when you chew your food. Once you swallow the food, your stomach also does some of this work. 
      ::机械消化当大块块变成较小的小块时,就会发生机械消化。也许毫不奇怪,这发生在你咀嚼食物时。一旦你吞下食物,你的胃也会做一些这样的工作。
    • Chemical digestion occurs when food is broken down into useful nutrients. This is a chemical process that begins as you start to chew your food. The saliva in your mouth starts this process. Once you swallow, the acid in your stomach further breaks down food. From the stomach, the foods moves into the small intestine. In the small intestines, another set of chemicals goes to work. Are you surprised? Your small intestine, and not your stomach, does most of the work!
      ::当食物分解成有用的营养物时, 就会发生化学消化。 这是一个化学过程, 开始于你开始咀嚼食物的时候。 你嘴里的唾液开始这个过程。 一旦吞咽, 你胃里的酸会进一步分解食物。 从胃部, 食物会进入小肠部。 在小肠部, 另一组化学物质会起作用。 你感到惊讶吗? 你的小肠部, 而不是胃部, 大部分的工作都是做!

    Absorption
    ::吸收吸收

    After food is broken down into nutrient molecules, then what? Once the food is broken down into nutrients, the nutrients can now be moved through the blood. This process is called absorption. Nutrients travel through the bloodstream to feed all your cells.
    ::食物分解成养分分子后, 然后呢? 一旦食物分解成养分, 养分现在可以通过血液移动。 这个过程叫做吸收。 养分通过血液流动来喂养所有细胞。

    Elimination
    ::消除

    Some substances in food can’t be broken down into nutrients. They remain behind after digestion has occurred. These materials cannot be absorbed. Any food that can’t be digested is passed out of the body as solid waste. This process is called elimination.
    ::食物中的某些物质无法分解成营养物质。 消化后,它们就留在后面。 这些材料不能被吸收。 不能被消化的任何食物都作为固体废料从身体中传播出来。 这个过程被称为消除。

    The Start of Digestion: Mouth to Stomach
    ::消化的开始: 向斯托马赫口吐口水

    Does the sight or smell of your favorite food make your mouth water? When this happens, you are getting ready for digestion.
    ::你最爱的食物的目光或气味 是否让你的口水?当发生这种情况时,你准备消化。

    Mouth
    ::嘴唇

    The mouth is the first digestive organ that food enters. The sight, smell, or taste of food stimulates the start of the digestive process. Your body starts with the release of saliva. Saliva wets the food, which makes it easier to break up and swallow. Other special chemicals start the chemical digestive process.
    ::口是食物进入的第一个消化器官。 食物的视觉、嗅觉或味道刺激了消化过程的开始。 你的身体从唾液的释放开始。 唾液湿了食物,这更容易分解和吞咽。 其他特殊的化学物质开始化学消化过程。

    Your teeth help to mechanically digest food. Look at the different types of human teeth in  Figure   . Sharp teeth in the front of the mouth cut or tear food when you bite into it. Broad teeth in the back of the mouth grind food when you chew. Your tongue helps mix the food with saliva and helps you swallow. 
    ::牙齿有助于机械消化食物。看看图中的人类牙型。口前的尖牙在咬口时会切开或撕裂食物。口后长牙在咀嚼时会磨碎食物。舌头帮助食物与唾液混合,帮助吞咽。

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    Teeth are important for mechanical digestion.
    ::牙齿对机械消化很重要。

    Esophagus
    ::Esophagus( 以硫磷)

    The esophagus is a long, narrow tube that carries food from the back of your mouth to the stomach. It has no other purpose. Food is pushed through the esophagus by special muscles. The muscles contract and relax, pushing the food along. The action is similar to when you squeeze your toothpaste from the tube. 
    ::食道是一条长的、狭窄的管子,将食物从嘴的背部送到胃部,没有别的目的。 食物被特殊的肌肉压穿食道。 肌肉收缩和放松,推动食物。 动作与你从管子挤牙膏时相似。

    Stomach
    ::胃

    The stomach is a sac-like organ at the end of the esophagus. It has thick muscular walls that contract and relax to squeeze and mix food. It's like having a washing machine inside your body tossing around food. This helps break the food into smaller pieces. It also helps mix the food with special chemicals that further aid the breaking down of food into nutrients.
    ::胃在食道的尽头是一种像肉眼一样的器官。 它有厚厚的肌肉壁, 紧紧的肌肉壁, 松绑, 挤压和混合食物。 就像在身体里有一台洗衣机, 在食物周围乱扔。 这有助于将食物碎成小块。 这也有助于将食物与特殊化学物质混合在一起, 进一步帮助食物分解成营养物质。

    Water, salt, and simple sugars can be absorbed in the stomach. These nutrients absorb directly into the blood from the lining of the stomach. However, most substances must undergo further digestion. This happens in the small intestine before they can be absorbed. 
    ::水、盐和简单的糖可以吸收在胃部。这些营养素直接吸收到胃内衬的血液中。然而,大多数物质必须进一步消化。这发生在小肠部,然后才能吸收。

    The Small Intestine
    ::小不小

    The small intestine is a narrow tube that starts at the stomach and ends at the large intestine. In adults, it’s about 7 meters (23 feet) long. Most chemical digestion, and almost all nutrient absorption, takes place in the small intestine.
    ::小肠道是一个狭小的管子,从胃开始,到大肠道结束。 在成年人中,这个管子长约7米(23英尺 ) 。 大多数化学消化和几乎所有营养吸收都发生在小肠道中。

    The small intestine is made up of three parts:
    ::小肠由三部分组成:

    1. The duodenum is the first part of the small intestine. It is also the shortest part. This is where most chemical digestion takes place. 
      ::是小肠肠的第一部分,也是最短的部分。这是大部分化学消化的地方。
    1. The jejunum is the second part of the small intestine. This is where most nutrients are absorbed into the blood. 
      ::这是大部分养分被吸收到血液中的地方
    1. The ileum is the last part of the small intestine. A few remaining nutrients are absorbed in the ileum. From the ileum, any remaining food waste passes into the large intestine.
      ::是小肠的最后一个部分。 少数剩余的营养素被吸收到中。 从中, 任何剩余的食物废物都会流入大肠中 。

    The Large Intestine
    ::大不列颠

    The large intestine is the last section of the digestive tract. It is a wide tube that connects to the small intestine. The large intestine carries the remaining food out of the body as waste. In the large intestine, water is absorbed into the body. The large intestine is about 1.5 meters (5 feet) long. It is larger in width, but shorter in length, than the small intestine.
    ::大肠是消化道的最后部分。 大肠是连接小肠的宽管。 大肠将剩余食物作为废物运出身体。 在大肠中,水被吸收到身体中。 大肠长约1.5米(5英尺),宽度大于小肠,但长度短于小肠。

    Lesson Summary
    ::经验教训摘要

    • The digestive system is the body system that digests food. It digest food in two ways, mechanically and chemically. Both help in the process of turning food into nutrients. The digestive system also eliminates solid food waste.
      ::消化系统是消化食物的人体系统,它以机械和化学两种方式消化食物,两者都有助于将食物变成养分,消化系统也消除固体食物废料。
    • The major organs of the digestive system include the mouth, esophagus, stomach, and small and large intestines. These organs all work together to help you gain energy from the food you eat. 
      ::消化系统的主要器官包括口腔、食道、胃、小肠和大肠,这些器官共同努力,帮助你们从食物中获取能量。
    • Digestion starts in the mouth. When food is swallowed, it travels through the esophagus to the stomach. In the stomach, digestion continues and a small amount of absorption of nutrients takes place.
      ::消化过程始于口中,当食物被吞食时,它会穿过食道进入胃部,在胃部,消化过程继续,并发生少量吸收营养物的情况。
    • Most chemical digestion and nearly all absorption of nutrients take place in the small intestine. This organ consists of three parts: duodenum, jejunum, and ileum.
      ::大部分化学消化和营养物质几乎全部吸收在小肠中,这种器官由三部分组成:二元、六元和二元。
    • The large intestine is the last stop in the digestive system. This is where water is absorbed. The food not digested is released as waste. 
      ::大肠是消化系统的最后一站,这里是吸收水的地方。未消化的食物作为废物释放。

    Lesson Review Questions
    ::经验回顾问题

    Recall
    ::回顾

    1. What organs help in the digestion of food?
      ::什么器官能帮助消化食物?
    1. Describe the roles of the mouth, esophagus, stomach, and intestines in digestion.
      ::描述口腔、食道、胃和消化肠的作用。

    Apply Concepts
    ::应用概念

    1. How are the mechanical and chemical digestive processes similar and different?
      ::机械和化学消化过程如何相似和不同?

    Points to Consider
    ::需要考虑的要点

    In the digestive system, food is digested and its nutrients are carried by the blood to the cells around our body. The blood is part of the cardiovascular system. 
    ::在消化系统中,食物被消化,其养分由血液携带到我们身体周围的细胞中,血液是心血管系统的一部分。

    1. What organs make up the cardiovascular system?
      ::心血管系统是由什么器官构成的?
    1. Besides nutrients, what other things are transported by the blood?
      ::除了养分之外,还有什么其他东西 是由血液传播的?