I. Answer the following questions:

1. What stomachs have the horse and the pig? 2. In what part of the stomach is the gastric juice secreted? 3.How does the gastric juice penetrate the mass of food in the first part of the stomach? 4. What does the percentage of hydrochloric acid depend on? 5. What enzyme does the saliva of the pig contain? 6. Due to what is the action of ptyalin stopped? 7. Where do contractions of the stomach walls start? 8.In what direction are the softened parts of the mass of food carried?

II, Pill in the blanks with the required words given below:

1.The pig's stomach is .... 2. The gastric juice can penetrate the mass of food in the first part of the stomach only… . 3. The action of the ptyalin ... due to the acidity. 4.Contractions of the stomach walls ... at the middle portion. 5. The ... parts of the mass of food are carried forward ... . 6. The saliva of the pig contains ..(ptyalin, simple, slowly, to stop, softened, to start, the rear).

III. Translate Into Russian:

1. The horse and the pig have a simple stomach, containing only a single compartment. 2. All the change which food undergoes within the digestive tract to prepare it for absorption and use in the body are known as digestion. 3. The above-mentioned changes which occur during digestion are both mechanical and chemical. 4. Ptyalin is the enzyme contained in the saliva of man and certain animals including the pig. 5. Ptyalin changes the starch of the food, which is insoluble, into sugar, which is soluble. 6. Besides the digestive glands there is a variety of other glands in the body. 7. As a result of the digestive processes the digestible portion of the food consumed is converted into sugars, fatty acids, glycerol and amino acids. 8. Exceedingly large amounts of saliva are secreted by the larger farm animals, especially when eating dry feed.

Text № 8 The Thyroid Gland.

This gland consists of two parts lying on each side of the trachea at its upper end. It produces an internal secretion which contains the hormone thyroxine – a crystalline product containing about 65 percent of iodine. Thyroxine is an iodine- containing amino acid as the protein thyroglobulin.

The removal of the thyroid early in life results in all species in a stunting of physical , mental, and sexual development.

In adult animals the hair and skin show premature aging ,and mental and physical sluggishness may develop. In all cases there is a lowered basal metabolism.

The mature animal body contains less than 0.00004 percent of iodine, but if this minute amount is not maintained through the food , the disease called goitre results. It usually affects new-born pigs ,lambs, calves ,and foals. Goitre in new –born farm animals can be entirely prevented by supplying small amounts of iodine to the pregnant animals during at least the last half of the pregnancy period.

EXERCISES:

1.Answer the following questions:

1.What does the thyroid gland consist of?2.What is thyroxine?3.What happens in the case of the removal of the thyroid gland early in life?4.What is the primary function of this gland?5.How many percent of iodine does the mature animal body contain?6.Where is half of this iodine concentrated?7.How can goitre be prevented in new-born farm animals?