For most people， the liver and the pancreas① just keep chugging② along. You can’t see or feel these vital organs working.
The liver does many things. It’s kind of like a factory hidden away inside your body. It has about 500 different jobs to do. It’s a chemical plant. It’s a storage facility for energy. It’s a vitamin bank and a poison control center. Your liver is on the right side of your upper abdomen③. It’s tucked under your ribs for protection.
Weighing in at three to four pounds in adults， the liver is the largest internal organ—and one of the most complicated. It stores nutrients and vitamins. It makes liquid called bile that is vital in digestion. It filters harmful stuff like drugs， alcohol， caffeine and nicotine from the blood. It makes parts of the blood and gives blood the ability to clot when you get a cut.
Perhaps most important， the liver helps break down and store food. All nutrients except fat get into your bloodstream through the liver. It helps your metabolism—the process that keeps you supplied with the energy you need to stay alive and do all your daily activities.
During digestion， the solid food you eat gets broken down in the stomach and the intestines④. Much of the food is turned into a substance called glucose， or blood sugar. Glucose is the main source of energy for your cells and your brain. You don’t use all your glucose at once， though. Some of it is stored and released slowly into the body when it’s needed. Where is it stored？ You guessed it. The liver. The liver changes glucose into a starchy material called glycogen⑤ that it can store.
A grown up’s liver stores about 3 ounces of glycogen at a time—enough to last an average person about 18 hours. When the body needs energy， the liver changes the glycogen back into glucose and send it to the cells (The liver has a limited storage area for glycogen； any food that it can’t handle gets stored as fat.).
Another important part of you works with the liver to keep your energy level up and your cells working right. It’s called the pancreas. The pancreas is about 6 inches long. It makes about one quart of pancreatic⑥ juice every day. The juices contain enzymes—chemicals that speed digestion.
The pancreas has two jobs. Its juices help break down food in your intestines. And it releases a vital substance called insulin into your bloodstream. Insulin makes it possible for your cells to absorb and use blood sugar. Insulin is made by special cells called beta cells. They’re found in a small portion of the pancreas called the “islets of Langerhans.”
When the level of sugar in your blood goes up， the cells in the islets of langerhans get busy making insulin so that you can take advantage of the energy in your food.
What can go wrong with your liver and pancreas？ The liver is remarkable because it heals itself when it’s damaged. But if there’s too much poison in the body for the liver to handle or if someone puts harmful substances like drugs or alcohol in the body every day， it can be harmed.
Certain diseases， including cancer， can affect the liver too. Since the 1960s， doctors have been able to transplant⑦ livers from people who have just died into people whose livers aren’t working very well. The operation is dangerous and complicated， but there have been many successful liver transplants.
You have probably heard of an illness called diabetes. This problem sometimes develops when the pancreas can’t produce enough insulin to allow the cells to soak up glucose from the blood fast enough. The body doesn’t get enough energy. Diabetes is a serious illness， but it can be treated successfully with injections of insulin.
① pancreasn. 【解】胰腺
② chugvi. 发出轧轧声前进 n. 轧轧声(引擎排气声)
③ abdomenn. 腹，下腹；腹部
④ intestinesn. 肠
⑤ glycogenn. 【生化】糖原
⑥ pancreaticadj. 胰的
⑦ transplantvt. 【医】移植[(+to/into)]；移植；移种
肝脏与胰腺
对于大多数人来说，肝脏和胰腺只是像机器一样喀喀嚓嚓不停地工作。你看不到，也感觉不到这些重要的器官在工作。
肝脏的确有许多功能。它好像隐藏在你体内的一个工厂。它大约有五百个不同的任务。它是一座化工厂，一个能量贮存装置。它是一个维生素贮存库和毒品控制中心。你的肝脏位于上腹的右侧，藏在你的肋下被保护着。
成人的肝脏重三至四磅，是人体内最大的器官——也是最复杂的器官之一。它贮存养分和维生素。它产生的一种叫做胆汁的液体，对于消化至关重要。它能过滤血液中的有害物质，例如毒品、酒精、咖啡碱以及尼古丁。它能制造血液的部分成分，你有伤口时，它能使血液具有凝固力。
或许最重要的是，肝脏有助于消化和贮存食物。除脂肪以外，所有的营养成份都经过肝脏进入你的血液。它有助于对你起新陈代谢的作用——这种过程能为你提供维持生命和每天活动所必需的能量。
在消化过程中，你吃的固体食物在胃和肠内得到分解。大部分食物变成一种叫做葡萄糖或血糖的物质。葡萄糖是你的细胞和大脑的能量的主要来源，然而，你不会一下子把所有的葡萄糖都用完。一些葡萄糖被贮存起来，根据需要，慢慢地释放入体内。它在哪里存着呢？你猜对了，在肝脏里。肝脏把葡萄糖变成一种能够贮存的淀粉物质，叫做糖原。
一个成人的肝脏一次能贮存大约三盎司的糖原——足够一个普通人用18个小时。人体需要能量时，肝脏会把糖原再变成葡萄糖送入细胞(肝脏贮存糖原的地方有限，它不能处理的食物就作为脂肪贮存起来)。
你还有一个重要的内脏同肝脏一起工作，维持能量平衡，使细胞正常工作。它叫胰腺。胰腺大约有六英寸长。每昼夜生产大约一夸脱胰液。胰液含有酶——一种加速消化的化学物质。
胰腺有两个任务。胰液有助于肠内食物的分解，还能把一种叫胰岛素的重要物质送入血液。胰岛素能够使细胞吸收并利用血糖。胰岛素是由叫做贝塔细胞的特殊细胞制造的。它们位于胰腺上叫做“胰岛”的那一小片地方。
当你血液中的糖含量上升时，胰岛上的细胞便忙于制造胰岛素，以使你利用食物中的能量。
你的肝脏和胰腺可能出什么毛病呢？肝脏非常了不起，因为它受到损害时能自愈。但是，假如肝脏需处理的毒素过多，或者，假如某人每天都往你体内塞进许多有害物质，例如毒品或酒精，它就会受到损害。
某些疾病，包括癌症，也能影响肝脏，自60年代以来，医生们已能够把刚刚死去的人的肝脏移植到肝脏有毛病的人身上。这种手术是危险的，复杂的，但也有许多成功的肝脏移植。
你也许听说过一种叫糖尿病的病症。当胰腺不能产生足够的胰岛素供细胞尽快地从血液中吸收葡萄糖时，就常常会发生这种疾病，这时人体便得不到足够的能量。糖尿病是一种严重的疾病，但它能通过注射胰岛素进行有效治疗。
