The digestive system

We need food in order to live; it is the fuel for our body’s energy and growth. There are three main kinds of food: protein (found in meat, cheese, and nuts, for example), carbohydrates (found in bread and potatoes), and fat (found in oils and butter). Proteins are used for repairing the body and for growing; carbohydrates and fats are needed for providing energy.

Digestion is a process that begins when we put food in our mouths and ends when the food has been absorbed into the bloodstream. It takes up to eighteen hours for digestion to occur. This is not surprising because our food has to travel through more than 26 feet of coiled-up tubing called the small intestine. On its journey food gets broken down by acid and enzymes. An enzyme is a chemical that changes food into a substance we can easily absorb.

When we chew, our teeth break up food into small pieces for swallowing. Food then travels down a muscular tube called the esophagus, to the stomach. The stomach is a thick muscular sac positioned on the left side of the body just beneath the ribs. The upper region of the stomach, closest to the heart, is called the cardiac region. Below that is the crescent part of the sac called the fundus. The pyloric region is tubular and connects the stomach to the small intestines. The wall of the stomach is made up of three thick layers of muscle. One layer is composed of longitudinal, one of circular, and the other of oblique (diagonal) fibers. The powerful contractions of these muscles break up the food, mix it with gastric juice, and move it down the tract. Gastric juice is a mixture of hydrochloric acid and enzymes that further digest the food. Gastric juice and mucus are secreted by the small gastric glands in the lining of the stomach. The mucus helps protect the stomach from its own digestive enzymes and acid. The partially digested food, called chyme, is pushed through the pyloric sphincter into the small intestine. The pyloric sphincter is similar in structure and function to the lower esophageal sphincter.

In the small intestine food is broken up into useful substances and waste substances by enzymes, which are produced by a gland called the pancreas. Inside the small intestine finger-like bumps, known as villi, contain blood vessels that absorb the useful substances into the bloodstream. Waste substances remain and pass into the large intestine, where water is absorbed until the waste becomes solid. This waste is later expelled from the rectum.

2. COMPREHENSION CHECK.

1. Mark the following statements as true or false:

a) Food is the fuel for our body.

b) Fats and proteins are used for providing energy.

c) Digestion doesn’t last long.

d) Food is broken down by acid.

e) The stomach is a thin muscular sac positioned on the right side of the body.

f) The pyloric region is circular and connects the stomach to the large intestines.

g) Gastric juice is a mixture of hydrochloric acid and proteins.

h) The mucus protects the stomach from its digestive enzymes.

i) In the small intestine food is broken up into waste substances by enzymes produced by the gastric glands.

j) Waste substances pass into the large intestine and are later expelled from the rectum.

2. Check your understanding of the text by answering the questions:

a). What are the main kinds of food?

b). Why are carbohydrates used?

c). What is digestion?

d). What is an enzyme?

e). What happens when we chew?

f). Where does food get after swallowing?

g). How is the upper region of the stomach called?

h). Where is the fundus?

i). What is the wall of the stomach made up of?

j). What happens to food as a result of the contractions of the stomach muscles?

k). Where are gastric juice and mucus secreted?

l). What is the pyloric sphincter like?

m). What absorbs useful substances?

3. Find in each paragraph the sentence which conveys the main idea.

3. LANGUAGE FOCUS.

1. Complete the chart filling in the missing derivatives (where possible):

noun	verb	adjective
part
	to grow
		tubular
provision
	to mix
		digestive
power
	to contract
		productive
absorption
		muscular
connection
circle

2. Looking through the lists of words below match the words which are: a) contrary or b) similar in meaning:

a)	b)
thick	to end	to occur	to start
to absorb	useless	to compose of	beneath
upper	soft	travelling	to name
useful	thin	to call	similar
solid	above	like	to make up of
beneath	to secrete	below	journey
to begin	lower	to begin	to happen

3. Find the words in the text that mean:

coiled-up tubing

chemical changing food into easily absorbed substances

muscular tube

muscular sac located on the left side of the body

crescent part of the sac

mixture of hydrochloric acid and enzymes

partially digested food

4. Translate into English using the vocabulary of the Unit:

а). Чтобы жить, человеку нужна пища.

б). Белки, углеводы и жиры – три основные вида пищи.

в). Пищеварение начинается, когда пища попадает в рот.

г). Ферменты преобразуют пищу в легко поглощаемые вещества.

д). Желудок представляет собой толстый мышечный мешочек, расположенный с левой стороны, ниже ребер.

е). Сокращения желудочных мышц расщепляют пищу и смешивают ее с желудочным соком.

ж). Кровеносные сосуды поглощают полезные вещества.

з). Отходы выводятся из тела человека через прямую кишку.

4. FOLLOW-UP ACTIVITIES.

1. Name all parts of the digestive system and explain their functions.

2. Write an essay about the digestive system.

Дата добавления: 2015-09-03