The Alimentary Canal

Digestion takes place in the alimentary canal, which is made up of several organs, each with a particular function. The alimentary canal is a winding tube that begins at the mouth and ends at the rectum. In an adult, it is about 9 metres (30 feet) long. The food we eat passes slowly through the canal, pushed along by movements of the muscles in the canal walls. The valuable part of the food goes into the blood, and the waste is expelled from the body. Teeth cut and grind the food. Salivary glands make saliva, which contains the enzyme ptyalin. This mixes with the chewed food, and starts the digestive process. Gullet leads to the stomach. Liver makes bile for use in digestion in the small intestine. Strong movements of the stomach walls thoroughly mix the food with gastric juices which contains the enzyme pepsin. Gall bladder stores bile until needed. Pancreas makes digestive juices containing various enzymes for use in the small intestine. Duodenum receives pancreatic juices and bile. Small intestine completes the digestive process. Blood and lymph vessels in the intestine walls absorb the digested food particles. The food is then carried round the body to nourish the living cells. Large intestine receives waste substances, which are then expelled from the body as faeces.

Answer the questions to the text:

1. What takes place in the alimentary canal?

2. Where does the alimentary canal begin and end?

3. Where does the valuable part of the food go?

4. What do salivary glands make?

5. What intestine completes the digestive process?

6. What vessels in the intestine walls absorb the digested food particles?

7. What is the length of the alimentary canal?

8. What organ produces bile?

9. How is the food carried round the body?

10. What gland makes digestive juices?

11. What organs of the alimentary tract can you name?

Task. Be ready to speak about the digestive system and digestion.

Ex.12. Skim the text and do the tests:

LIVER

The liver is the largest and most complex gland in the body, and plays an important part in digestion Most of it lies in the right upper side of the abdomen under the diaphragm and ribs. Some 500 chemical, processes take place in it. Through the hepatic portal vein, the liver receives most of the food substances from digestion. It stores some, and regulates the amount of food that enters the main part of the body's bloodstream.

The liver in the average adult weights about 1.5 kilos. It is covered by a tough, fibrous capsule. The gallbladder and its ducts lie beneath the right side of the liver. The liver is composed of up to 100,000 lobules. Each lobule is surrounded by capillaries from hepatic portal vein and the hepatic artery. More than a liter of blood passes through the liver each minute.

The liver stores vitamins (except vitamin C) until, they are required.

Liver cells also recycle various substances, such as hemoglobin, that are needed by the body. In addition, the liver destroys many poisonous substances that may be absorbed into the body and acts as an organ of excretion. Bile salts and bilirubin are formed in the liver and pass into the bile ducts. Then they are excreted into the duodenum or stored in the gall bladder. Unwanted proteins are destroyed and changed into urea, which is carried in the bloodstream to the kidneys and excreted in the urine.

1. The liver is the …gland in the body

1. a. smallest;

2. b. largest

3. c. longest;

2. Some…processes take place in it

1. a.300;

2. b. 400;

3. c 500;

3. Most of liver lies ... under the diaphragm and ribs.

1. in the right upper side of the abdomen;

2. in the left upper side of the abdomen;

3. in the right lower side of the abdomen;

4. The liver in the average adult weights... .

1. about one kilo;

2. about two kilos;

3. about 1.5 kilos;

5. Тhе gallbladder and its ducts lie ... .

1. beneath the right side of the liver;

2. above the right side of the liver;

3. beneath the left side of the liver;

6. Each ... is surrounded by capillaries from hepatic portal vein and the hepatic artery.

1. side;

2. branch;

3. lobule

7. More than ... of blood passes through the liver each minute.

1. two litres;

2. one and a half litre;

3. one litre;

8. The liver stores vitamins (...) until, they are required.

1. except vitamin C;

2. except vitamin B;

3. except vitamin A;

9. Liver cells also recycle various substances, such as … .

1. protein;

2. lipids;

3. hemoglobin;

10. The liver destroys many poisonous substances that may be absorbed into the body and acts as ... .

1. an organ of excretion;

2. an organ of digestion;

3. an organ of respiration;

11. Bile salts and bilirubin are formed in the liver and pass into ... .

1. the duodenum;

2. the kidneys;

3. the bile ducts;

12. Unwanted proteins are destroyed and changed …, which is carried in the bloodstream to the kidneys.

1. into urine;

2. into urea;

3. poisonous substances;