ascending colon -

cecum -

Vermiform appendix

-descending colon

-sigmoid colon

Fig. 17-1. The digestive system

Exercise 9. Read the information about enzymes. Explain the role of enzymes.

Enzymes are proteins that speed the rate of chemical reactions, but at the same time they are not themselves changed or used up in these reactions. An enzyme is a highly specific substance, it acts only in a certain type of reaction, involving a certain type of food molecule. For example, the carbohydrate-digesting enzyme amylase only splits starch into maltose. Another enzyme is required to split maltose inlo two molecules of glucose (monosaccharide). Other enzymes split fats into their building blocks, glycerol and fatty acids, and still others split proteins into amino acids.

Exercise 10. Look at Table 17-1. Name all products secreted by the organs of the digestive tract and accessory organs. What are their actions?

Table 17-1. Digestive Juices Produced by the Digestive and Accessory Organs

Organ	Main Digestive Juices Secreted	Action
Salivary glands	Salivary amylase	Begins starch digestion
Stomach	Hydrochloric acid(HCl)	Breaks down proteins
	Pepsin	Begins protein digestion
Small intestine	Peptidases	Digest proteins to amino acids
	Lactase, maltase, sucrase	Digest disaccharides to monosaccharides
Pancreas	Sodium bicarbonate	Neutralizes HC1
	Arnvlase	Digests starch
	Trypsin	Digests proteins to amino acids
	Lipases	Digest fats to fatty acids and glycerol
	Nucleases	Digest nucleic acids
Liver	Bile salts	Emulsify fats

II. Grammar Exercises

Exercise 1. Translate the following sentences, pay attention to the words one and

that.

1. One of the lungs has three lobes, the other one only two.

2. The brain of man is heavier than that of any lower animal.

3. That portion of the alimentary tract which forms the large intenstine consists of thececum, colon and rectum.

4. The valve that divides the atrium and the ventricle of the right chamber is called thetricuspid valve.

Exercise 2. Choose the correct participle, translate the sentences.

1. Drugs (contained, containing) impurities or some other ingredients are calledcontaminated.

2. According to official data the first counterfeit prescription drug (detected, detecting) in 1950 was a hormone 60 % potent.

3. Narcotics were the first counterfeit synthetic painkillers (selling, sold) to hospitals by the New York Mafia.

4. Counterfeit drugs also include drugs (prescribing, prescribed) for the treatment of cancer, arthritis, hypertension and other conditions.

5. In developed countries there are many secret drug (produced, producing) plants.

6. Illicit plants manufacture out-dated and (contaminated, contaminating) medications.

7. At the chemists' all medicines are kept in drug cabinets, on shelves (protecting, protected) from light and in the refrigerator.

8. Some boxes have blue labels (indicated, indicating) drugs (used, using) for injections.

9. A pharmacist (taking, taken) prescriptions and (delivering, delivered) drugs is called a dispensing pharmacist.

Exercise 3. Make gerunds from the following verbs, translate them.

Model: to make — making.

To perfonn, to read, to sit, to get, to enter, to study, to write, to consult, to prescribe.

Exercise 4. Translate these sentences and define the part of speech of the words in bold type.