I. Pre-reading and reading tasks.

1. Study the meaning and pronunciation of the following words:

2. Make sure you know the following words and word combinations:

3. Comment on the headline of the text before reading it. What do you know about the cell? Read the text and point out what information is new for you.

THE CELL

A cell is the fundamental organizational unit of life. One of the most important generalizations of modern biology is the cell theory. There are two components of the cell theory. It states: (1) that all living things are composed of cells and (2) that all cells arise from other cells. Living things are chemical organizations of cells and capable of reproducing themselves.

There are many types of cells, and just as many classifications to go with them. There are plant cells, animal cells, eucaryotic cells, procaryotic cells, and many others. Also within each of these divisions, there are smaller subdivisions pertaining to the specific properties or functions of the cells. Cells exhibit considerable variation in properties based on different arrangements of components. Cells also vary in size, although most of them fall in the range of 5 to 20 mm

In total there are about 50 billion cells in your body! Each cell is so small it cannot be seen with the naked eye. However, with the help of a microscope we are able to study cells and discover how they work.

Nearly all cells have a nucleus, which is the control center of the cell. Ribosomes in cells do as the nucleus tells them. They act like factories, making proteins and other chemicals for our body. To work properly a cell needs energy and this energy comes from the food we eat. Power stations in the cell, called mitochondria, change the energy stored in food into a form of energy that can be used by the cell.

We start life as one cell, which divides into two. These cells also divide, and as more cells grow they form different shapes and sizes. Each of these different types of cell has its own job to do. Similar types of cell will join together to make tissues, which form organs like our brain and lungs.

How long a cell lives depends upon the type of cell it is. Skin cells die quickly and are constantly replaced by new cells. Nerve cells should last a human lifetime and cannot be replaced even if they are damaged.

The control center of the cell is called the nucleus. Inside the nucleus of each cell lie tiny threads called chromosomes. Inside the chromosomes are smaller structures called genes. It is in the genes that the instruction manual lies. The instructions are in the form of a chemical called DNA. DNA is shaped like a twisted ladder, known as a double helix.

Ribosomes make proteins, as instructed by the nucleus. The golgi apparatus packs up the proteins made by ribosomes, ready to be stored or transported. Lysosomes help break down substances in the cell. The cell membrane allows food in the form of sugars to enter, and allows waste chemicals made in the cell pass out. Cilia are like tiny hairs that beat, pushing mucus or fluid over the cell surface. Inside a cilia there are 20 little tubes, arranged in pairs, to make it strong.

Notes to the text:

To fall in the range – входить в диапозон.

Classifications to go with them – классификации, которые соответствуют им.

II. COMPREHENSION CHECK.

1. Say whether the following statements are true or false:

2 Think of 8 questions to the text.

III. LANGUAGE FOCUS.

1. Say it in another way (give synonyms):

a) All living things consist of cells.

b) Cells are also different in size.

c) Each cell is so small that it can be seen only with the help of a microscope.

d) Almost all cells have a nucleus.

e) A cell needs energy to work in a proper way.

f) Mitochondria change the energy kept in food into a form of energy that can be used by the cell.

g) The cells form various shapes and sizes.

h) Inside the nucleus of each cell lie very small threads called chromosomes.

i) Ribosomes make proteins as the nucleus tells them.

j) The cell membrane permits waste chemicals made in the cell pass out.

k) Cilia look like minute hairs.

l).Little tubes are set (settled) out in pairs.

1. Put the parts of the sentences in the right order:

a) Themselves, of, living, are, things, reproducing, capable.

b) Properties, in, considerable, exhibit, cells, variation.

c) The, a, is, center, nucleus, control, cell, the, of.

d) Eat, the, from, food, comes, we, energy, the.

e) Constantly, new, by, cells, are, skin, replaced, cells.

f) Of, nucleus, cell, threads, inside, each, lie, the, tiny.

g) Break, lysosomes, substances, down, help, cell, the, in.

h) Many, are, inside, little, a, there, tubes, cilia.

2. Translate from Russian into English:

А). расположенные попарно, расщеплять вещество, мельчайшие волоски, в общем, почти все клетки, контролирующий центр клетки, клеточная мембрана, химические отходы.

Б).

а). Все живые организмы состоят из клеток.

б). Жизнь начинается из одной клетки.

в). Продолжительность жизни клетки зависит от типа клетки.

г). Каждая клетка очень мала, поэтому ее нельзя увидеть невооруженным глазом.

д). У каждой клетки своя функция.

е). Чтобы хорошо работать, клетке нужна энергия, которая поступает с пищей.

ж). Митохондрии изменяют накопленную в пище энергию в такую энергию, которой может воспользоваться клетка.

з). Клетки различаются по свойствам и размерам.

и). Нервные клетки не восстанавливаются.

к). Одинаковые клетки соединяются и образуют ткани.

IV. FOLLOW-UP ACTIVITIES.

1 Discuss will your partner:

a) The cell theory.

b) The nucleus as the control centre of the cell.

c) Ribosomes, genes and DNA.

ADDITIONAL TEXT

I. Read the text carefully to fulfil the tasks that follow.

CELLS

With the availability of the first microscopes, researchers began to observe the microscopic structure of many substances, and in 1665 the Englishman Robert Hooke described having seen what he called cells in a piece of cork. He used this term because the cork appeared to be composed of thousands of tiny chambers that resembled the individual sleeping rooms in monasteries at the time, which were called cells. He was not aware that he was viewing just the cell walls, which were the only structures remaining from what had once been living cells.

Hooke’s initial discovery led to other advances, such as the finding that unlike plant cells, which have thick cell walls, animal cells lack such a wall and instead have only a thinner, generally more flexible plasma membrane.

Cells were then found to exist independently or as one small part of an organism consisting of many cells, a multicellular organism. Hooke was the first to discover that some organisms consist entirely of a single cell. These unicellular organisms, such as thousands of species of bacteria and protozoa, carry out all necessary life-supporting functions within one cell without the help of other cells. In contrast, multicellular organisms have cells with specific functions, and together the aggregate of cells embodies a complex organism.

It took about 150 years after Hooke discovered cells before several important related facts were articulated. Two German scientists, Matthias Schleiden and Theodor Schwann were the first to explain, in 1838 and 1839 respectively, the basic tenets of what we now call cell theory:

1. Cells are the fundamental units of life.

2. Cells are the smallest entities that can be called living.

3. All organisms are made up of one or more cells.

The longest cells are certain nerve cells (neurons), which can reach over a meter in length. While an ostrich egg is 1,500 times the size of a human egg cell – which is 14 times the size of a human red blood cell, itself as much as 35 times the size of many small single-celled microorganisms – most cells do have one thing in common: They tend to be quite small. While the size range reflects considerable diversity, most cells are 0.5 to 40 microns in diameter (1,000 microns equals one millimeter).

Small cell size is thought to be a function of the restriction placed on them by the ratio of surface area to volume. Cells are constantly absorbing molecules from the surrounding medium and releasing molecules into the surrounding medium. These processes are more readily accomplished when a cell is small and the ratio of surface area to volume is quite large. As a cell increases in size, the amount of volume inside the cell increases much more rapidly than the amount than the amount of surface surrounding the cell, and in time the cell becomes too large to maintain a stable internal environment.

Many scientists believe that it is more difficult for the nuclear material to maintain control over the entire internal environment when a cell is over a certain size. Therefore, if a small nucleus is most often the rule, then an upper limit is placed on the size of most cells.

II. POST-READING TASKS.

1. Discuss in pairs:

a) Robert Hooke’s discovery and cell theory.

b) Cell structure and cell size.

2. Write an essay about cells, their structure and size.

UNIT 3

I. PRE-READING AND READING TASKS.

1. Study the vocabulary which is intended to aid your comprehension of the text:

2. Make sure you can supply an adequate translation for each of the following word combinations:

3. Read and translate the text.

HOW THE BODY WORKS

Do you know what lies inside your body and how your body works? How does each system in the body function and how do all the systems work together to make us the complex human beings we are?

Reading this text and the texts to follow you will see how each part of the body has its own special job to do, how we get the energy to live, and how we defend ourselves from harm. You will also learn about the five senses – vision, hearing, touch, taste, and smell – and how all we think and do is controlled by the brain in communication with our nervous system.

The human nervous system, composed of the brain, spinal cord, and peripheral nerves, connects the eyes, ears, skin, and other sense organs (the receptors) with the muscles, organs, and glands (the effectors). The nervous system functions in such a way that when a given receptor is stimulated, the proper effector responds appropriately.

The chief functions of the nervous system are the conduction of impulses and the integration of the activities of various parts of the body. Integration means a putting together of generally dissimilar things to achieve unity.

Our heart is the pump at the center of our blood system. Heart muscle is very strong as it has to pump blood through networks of small blood vessels around the body. Heart muscle contracts automatically; the number of times it contracts, or beats in a minute is known as the heart rate. An adult normally has a heart rate of about 70 beats a minute. At birth our heart rate is much faster than this – sometimes twice as fast.

Lungs take oxygen from the air into the blood and also get rid of carbon dioxide.

Our body skeleton provides a firm attachment for the body’s muscles. The ribcage is part of our skeleton – it protects our lungs and heart. Where bones meet there are joints, allowing movement to occur. Hands are complex bony structures that enable us to carry out intricate movements.

Our skin is a waterproof protective covering for the whole body. It is very delicate and sensitive.

Our intestine absorbs nutrients from food we have eaten and collects waste material. Behind the intestine lie the kidneys, which remove waste and pass it into our urine. The liver sorts out useful substances from toxic substances. It is the blood’s cleaning and sorting center. A vein called the portal vein connects the intestines directly to the liver, bringing to the liver blood that is rich in dissolved food. When the kidneys receive blood containing waste substances, they filter and remove these substances together with any excess water. The kidneys pass this waste, or urine, to the bladder, and pass the filtered, clean blood back to the heart.

II. COMPREHENSION CHECK.

1. Agree or disagree with the following:

a) Our heart is the pump at the center of our intestine.

b) The human nervous system is a part of our skeleton.

c) Our body skeleton protects our lungs and heart.

d) Hands are complex bony structure that enable us to achieve uniti.

e) Lungs take oxygen from the air into the blood and get rid of carbon dioxide.

f) Our skin absorbs nutrients from food we have eaten.

g) Behind the intestine lies the liver which removes waste and passes it into our uren.

h) The kidneys are the blood’s cleaning and sorting centre.

2. Answer the questions:

a) What are the 5 senses and how are they connected with our nervous system?

b) How does the nervous system function?

c) What are our thoughts and actions controlled by?

d) What can you say about integration?

e) What is the liver intended for?

f) What passes the filtered, clean blood back heart?

III. LANGUAGE FOCUS.

1. Give nouns related to the following verbs:

2. Explain what is meant by the following word combinations:

2. Translate the following sentences into English:

а). Наша кожа – это водонепроницаемая защитная оболочка для всего тела.

б). Легкие поглощают кислород из воздуха в кровь и, кроме этого, высвобождают двуокись углерода.

в). Основные функции нервной системы – это проведение импульсов и интеграция движений различных частей тела.

г). Грудная клетка – часть нашего скелета, она защищает легкие и сердце.

д). Все, что мы делаем и о чем думаем, контролируется мозгом в совокупности с нервной системой.

е). Нервная система человека, состоящая из головного и спинного мозга и периферических нервов, связывает глаза, уши, кожу и другие органы чувств с мышцами, органами и железами.

ж). Печень отбирает полезные вещества из токсичных и является центром очистки крови.

з). У взрослого человека частота сердечных сокращений составляет обычно приблизительно 70 ударов в минуту.

и). Руки – это сложные костные образования, которые дают возможность выполнять сложные движения.

к). Воротная вена связывает кишечник непосредственно с печенью, поставляя обогащенную питательными веществами кровь.

л). Почки проводят мочу к мочевому пузырю, а профильтрованную чистую кровь – обратно к сердцу.

IV. FOLLOW-UP ACTIVITIES.

1. Discuss with your partner:

a). The human nervous system.

b). Our heart and heart muscle.

c).The body skeleton and the skin.

d).The liver and the kidneys. Their functions.

ADDITIONAL TEXTS

IV. Read the texts carefully. Be ready to fulfil the tasks that follow.

THE SKIN

Skin is our protective coat – a complex covering of two layers. The top layer is the epidermis, which as well as being waterproof also protects us against germs. The cells in this layer are being shed all the time, with new cells growing in their place. The dermis layer beneath is much thicker, and is made up of elastic fibers. It contains blood vessels, sweat glands, and hair roots, called follicles. These all help to control our body temperature. In hot weather the blood vessels widen and allow more blood to flow near the cooler surface of the skin. Sweat glands produce salty droplets that evaporate on the body and cool it down. In cold weather muscles attached to hair follicles tighten, making our hairs stand on end. This traps a thin layer of warm air around the body. In addition, blood vessels narrow to keep the body’s heat in and away from the skin’s surface.

Nerve endings in the dermis enable us to feel heat, cold, pain, and pressure. They also help protect our bodies from damage. Our hands, lips, and soles of our feet are the most sensitive parts of our body because the skin on them has the richest supply of nerve endings.

SEEING

Our eyes work like cameras. Each eye has a pupil, which, similar to a camera’s aperture, is a hole that allows light to enter the eye. When it is dark our pupils enlarge to let in as much light as possible. The size of each pupil is controlled by the iris, which surrounds it. When light passes through the pupil it meets the lens. The lens causes the light to bend so that it shines on an area at the back of the eye called the retina. The retina is something like the color film in a camera in that an image can be formed on it. This image is upside down and is transmitted by the optic nerve to the brain, which enables us to interpret it right-side up.

TASTE AND SMELL

We are most familiar with the senses of taste and smell for the pleasure they can bring. However, they probably were developed to protect us from eating food that could be poisonous. Our sense of smell is much stronger than our sense of taste. When we taste food we rely on the smell and texture as well as the taste. This explains why we cannot taste food very well when we have a cold.

When eating a pear, for example, scent from the fruit rises up the nose and dissolves in a mucus lining that covers the scent-sensitive cells at the top of the nose. These special odor-sensitive cells become stimulated when vapors are released from food, drinks, and the environment. They are called olfactory cells and they contain hairs on which mucus lies. Vapors dissolve in the mucus, causing nerve impulses to be sent to the olfactory lobe in the brain, where the smell is recognized and enjoyed. The pear’s sweetness is also sensed by taste buds on the tongue, and is similarly transmitted by nerve signals to the brain.

Our tongue contains about 10,000 taste buds, which pick up and respond to salt, sweet, sour, or bitter tastes. The taste buds are stimulated when chemicals from food are dissolved in the mouth’s fluid – our saliva. Combined together, the four basic tastes give us a range of subtle flavors.

HEARING

The part of the ear we see is shaped to collect sound and allow it to travel along the ear canal to the eardrum. Sound causes the eardrum to vibrate. Behind the eardrum are three small bones called hammer, anvil and stirrup, which get their names from their shapes. Vibrations from the eardrum cause the small bones to vibrate too, and these vibrations pass through an oval window to the cochlea. The cochlea is a coiled tube filled with liquid. Low-pitched sounds make the first part of the tube vibrate, while high-pitched sounds vibrate a part further up. These vibrations are picked up by nerve fibers connected to the brain. The brain can tell where the vibrations are occurring and so can tell one sound from another.

Ears help us to balance. There are three semi-circular canals in the ear. They contain fluid that moves when we change our position. The moving fluid sends signals to the brain that helps our body to adjust and keep its sense of balance.

V. POST-READING TASKS.

1. Imagine that you are making a speech on one of these topics:

a) The skin.

b) Seeing.

c) Taste and smell.

d) Hearing.

2. Write an essay describing human senses.

UNIT 4

I. PRE-READING AND READING TASKS.

І. Practise the pronunciation and study the meaning of the words:

2 Read and translate the text.

THE BRAIN

The brain looks like a mass of gray jelly and is very soft. It is protected in the hard, bony case known as the skull. The human brain is quite large but is wrinkled, which makes it compact.

The brain is the body’s control center. It is involved with what we do and what we think, as well as what we feel and remember. We also use our brain to learn. The left-hand side of our brain controls the right side of the body, and the right-hand side of our brain controls the left side of the body. Most people are right handed, because the left side of the brain is generally used more than the right side. It has been found that each side of our brain is responsible for different skills. The right side holds our artistic talent and imagination, and the left side is more responsible for practical abilities and logical thinking.

The cells that make up the brain are called neurons. Branches from the cells, called dendrites receive impulses from the nerves while axons transmit them. Our brain interprets the impulses and can tell where they are coming from and to what they are referring. The brain cells can also store information. A piece of stored information is called a memory. One part of our brain stores long-term memories, another part more recent memories.

The largest part of the brain consists of two sections. Together they are known as the cerebral hemispheres or cerebrum. The cerebrum is highly organized. It is arranged in areas that relate to different parts of the body and to different needs. Vision is interpreted at the back of the cerebrum; hearing and speech at the side. The areas for sensation and movement are in the middle. The area at the front of the cerebrum, the frontal lobes, controls our behaviour. Below and to the back of the cerebrum lies the cerebellum. It contains nerve cells that are mainly concerned with balance. Below this the brain is connected to the rest of the body by the spinal cord.

II. COMPREHENSION CHECK.

1. Express your agreement or disagreement with the following:

a) The human brain is quite small and very hard.

b) Most people are left handed because the right side of the brain is generally used more than the left side.

c) The brain is responsible for only one skill.

d) The cells that make up the brain can store information.

e) Vision is interpreted at the back of the dendrites.

f) Our behaviour is controlled by the spinal cord.

2 Answer the following questions:

a) Where is the brain located?

b) What does the brain look like?

c) Why is the human brain wrinkled?

d) Can the brain cells store information?

e) What cells of the brain receive impulses from the nerves?

f) How is the cerebrum organized?

g) What role does the cerebellum perform?

III. LANGUAGE FOCUS.

1. Give a) synonyms and b) antonyms to these words:??????????

2. Put the words in the right order to make up sentences:

a) Is, body, the, control, the, centre, of, brain, the.

b) Like, the, jelly, brain, looks, a, mass, grey.

c) The, one, more, used, left, side, of, the, brain, than, the, right, is.

d) From, nerves, the, receive, dendrites, impulse.

e) Information, is, a, stored, memory.

f) Two, of, sections, brain, the, consists.

g) Behaviour, the, controls, our, of, cerebrum, the, front.

h) Mainly, with, cerebellum, the, is, balance, concerned.

3. Translate the following sentences from Russian into English:

а) Мозг контролирует все движения тела.

б) Мозг участвует в том, что мы делаем и думаем, а также в том, что мы чувствуем.

в) Наш мозг отвечает за различные навыки и умения. Правая сторона мозга отвечает за наши артистические способности и воображение, а левая – за практические способности и логическое мышление.

г) Наш мозг интерпретирует импульсы и может определить, откуда они идут и к чему относятся. В заднем отделе больших полушарий обрабатывается то, что мы видим, а то, что слышим и говорим – в боковом.

д) Клетки мозга могут также накапливать информацию. Памятью называется накопленная информация.

е) Головной мозг очень хорошо устроен.

ж) Спинной мозг соединяет головной мозг с телом.

з). Большинство людей – правши, потому что левая сторона мозга, в целом, используется больше, чем правая.

и). Отростки клеток, называемые дендритами, получают импульсы от нервов, а аксоны передают их.

к). Клетки, составляющие мозг, называются нейронами.

л). Участок передней части больших полушарий, который называется передними долями, контролирует наше поведение.

IV. FOLLOW-UP ACTIVITIES.

Discuss with your partner:

1) The brain as a body’s control centre.

2) The brain cells – neurons, dendrites – and their functions.

3) The main sections of the brain and the interpretation of various sense organs, movement, behaviour, balance, etc.

ADDITIONAL TEXT

I. Read the text carefully. Be ready to fulfil the tasks that follow.

THE BRAIN

Evolutionarily, the vast majority of organisms above the level of the primitive invertebrate phyla have evolved sense organs in the anterior portion (front end) of their bodies that respond to the high concentration of incoming information there. The most anterior ganglion, or enlarged, organized, integrative mass of nervous tissue, is called the brain. It is the brain that is responsible for processing most of the incoming information.

In many species of invertebrates, the brain is not much larger than the other ganglia located along the rest of the longitudinal nerve cords. The brain of an invertebrate usually has considerably less dominance over the rest of the nervous system, and therefore the body, than is true for a vertebrate` brain in the same size category. The brain in most lower vertebrates is not capable of significantly more complex tasks than most invertebrate brains. But the early vertebrate brains reflect evolutionary trends that led to many of the brain developments that have helped distinguish the vertebrates from other groups of organisms.

In the higher invertebrates as well as in the vertebrates, the brain functions in coordination with, or in place of, the many localized, segmented ganglia that are usually little more than a stimulus-and-response apparatus. This large accumulation of nervous tissue receives and transmits sufficiently large amounts of data to give it considerable control over the rest of the organism. The brain also makes it possible for many of these organisms to learn.

II. POST-READING TASKS.

1. Define what the brain is and enumerate its functions.

2. Name the differences between the brain of an invertebrate and a vertebrate.

3. Sum up what you have learned about the brain and write an essay about it.

UNIT 5

I. PRE-READING AND READING TASKS.

1.Study the vocabulary which is intended to aid your comprehension of the text:

3 Make sure you can supply an adequate translation for each of the following word combinations:

4 Read and translate the text.

THE NERVES

Our nervous system is a busy network of nerves. It includes the nerves in our brain and the nerves that stretch throughout our bodies. Our brain is connected to the rest of our body by the spinal cord, a thick cable that runs down the spinal column in our back.

Nerves are made up of thin strands called neurons. There are millions of these throughout the nervous system and each consists of a cell body, which has short branches called dendrites. The long arm of the neuron is called the axon. Some axons are enclosed in a fatty layer called myelin, which helps to speed up the conduction, or passing, of nerve messages along the axon. Nerve cells in our spinal cord cannot be replaced, so spinal injury can be serious.

Nerves carrying sensations, such as pain, are known as sensory nerves. When a wasp stings your leg the sensory impulse travels up the leg and into the spinal cord. It is then transmitted to neurons in the gray matter of the cord, which link up with motor neurons. The impulse travels back down the leg in the motor nerve and the leg muscle tightens, making the leg jerk. The reflex action does not involve the brain.

Nerve impulses link up neurons by jumping across a gap called a synapse. When an impulse reaches the end of an axon, chemicals are released that allow it to pass across the synapse and on to the next neuron.

The axon of a motor neuron meets the muscle at a special junction called the motor end-plate. When the nerve impulse is received at the motor end-plate a substance called acetylcholine is released, which sticks to the outside of the muscle fiber, causing gates in the muscle fiber to open and let in sodium. This activity makes our muscle contract and movement occurs.

The brain and spinal cord compose the central nervous system. The somatic nervous system conducts nervous impulses that have already been processed, away from the central nervous system to the skeletal muscle tissue. The somatic nervous system is under voluntary control. All the parts of the nervous system, excluding the brain and spinal cord are collectively known as the peripheral nervous system.

The autonomic nervous system consists of the nerves that carry nervous impulses from the central system to the heart (cardiac muscles), to the muscles in the digestive system (smooth muscles), and to the glands. All of these muscles and glands contract and function involuntarily. The autonomic nervous system is subdivided into two parts, the sympathetic and parasympathetic systems. These function in opposition to one another; the first inhibits organs, while the latter usually excites organs.

II. COMPREHENSION CHECK.

1. Mark the following statements as true or false:

a) Our nervous system includes the nerves in our brain.

b) Our brain is connected to the rest of our body by the spinal column.

c) Nerves are made up of millions of neurons, each consisting of a cell body, which has short branches called dendrites.

d) Nerve cells in our spinal cord can be replaced.

e) Myelin slows down the conduction of nerve messages.

f) Our muscles contract and movement occurs due to nerve impulses.

g) The central nervous system is composed of the brain and spinal cord.

h) All parts of the nervous system are known as the peripheral nervous system.

i) The peripheral nervous system is subdivided into 2 parts: the sympathetic and parasympathetic.

j) The autonomic nervous system conduct nervous impulses from the central system to the heart.

k) Cardiac muscles, smooth muscles and glands contract and function under voluntary control.

l) The reflex action involves the brain.

2. Prepare extensive answers to these questions:

a) What does the nervous system include?

b) What connects our brain to the rest of our body?

c) What are our nerves made up of?

d) What is the axon?

e) What can the replacement of nerve cells in our spinal cord cause?

f) What happens when a wasp stings your leg?

g) What is the synapse?

h) How does a muscle contract and movement occur?

i) What is the difference between the central and peripheral nervous systems?

j) How do sympathetic and parasympathetic nervous systems function?

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

III. LANGUAGE FOCUS.

1. Find in the text: a) synonyms and b) antonyms to the following words:

2. Change the words in capital letters to fit the context of the sentence:

a) Our …… system is a busy network of nerves (NERVE).

b) The spinal cord ………our brain to the rest of our body (CONNECTION).

c) Myelin speeds up the ……….. of nerve messages along the axon (CONDUCT).

d) Spinal …… can be serious if nerve cells in our spinal cord are ……. (INJURE, REPLACEMENT).

e) ……. nerves are nerves carrying sensations (SENSE).

f) The leg muscle …. and the leg jerks (TIGHT).

g) The …. nervous system includes all the parts of the nervous system except the brain and spinal cord (PERIPHERY).

h) Glands and cardiac and smooth muscles ….. and function …… (CONTRACTION, VOLUNTEER).

3). Translate the sentences into English using the vocabulary of the unit:

a) Спинной мозг связывает мозг человека и его тело.

б) Нейрон – это нервная клетка, состоящая из тела и отходящих от него отростков: дендритов и аксона.

в) Серьезное повреждение спинного мозга может быть вызвано замещением в нем нервных клеток.

г) Головной и спинной мозг составляют центральную нервную систему.

д) В результате воздействия на чувствительные нервные окончания происходит возбуждение нервных тканей, которое делает возможным сокращение мышечных волокон и мышц.

е) Рефлекс – это непроизвольное движение какой-либо части тела в ответ на раздражение.

ж) Автономная нервная система состоит из двух частей, которые выполняют противоположные функции.

IV. FOLLOW-UP ACTIVITIES.

1) Name different constituents and types of our nervous system and define their functions.

2) Discuss the following problem in pairs: The nervous system plays the leading role in the regulation of all physiologic processes in a complex organism.

3) Write an essay about our nervous system.

ADDITIONAL TEXT

I. Read the text carefully to fulfil the tasks that follow.

THE NERVOUS SYSTEM

Neurons are among the most excitable cells in the body. As a group, they respond to a wide range of electrical, chemical, thermal, or mechanical stimuli, transmitting messages to one another, to muscles, and to endocrine organs (hormone-secreting glands). Together, all the neurons and their supporting cells (glial cells) compose the central nervous system.

Neurons do not exist in sponges (phylum Porifera) or more primitive organisms. The first neurons appear among the coelenterates (phylum Cnidaria), which include jellyfish, hydra, and anemones. Of all living organisms, coelenterates have the simplest nervous arrangement, with only two types of nerve cells: receptor-conductor cells (those that respond to the stimuli and pass it on) and effector cells (those that contract when the stimulus reaches them). They have none of the alternative types that allow for the increased flexibility of response typical of higher organisms.

As the neurons in a nervous system increase in number, so does the complexity of behavioral responses an animal can have. Since one neuron communicates with nearby neurons, which in turn communicate with other neurons, the total number of possible neuron connections increases exponentially as the total number of neurons increases.

A roundworm (phylum Nematoda) is an organism that moves very little. It has only about 160 neurons. The leech (phylum Annelida), slightly more mobile, has about 13,000 nerve cells. An octopus (phylum Cephalopoda), which has considerable control over its movements and behavior, has over 1 billion neurons. And humans (phylum Chordata) have more than 10 billion neurons.

Changes in the physical or chemical environment (i.e., due to motion, sound, light, heat, or chemicals) can be converted into nervous impulses. The environmental change is known as the stimulus, and the neuronal response is the neural impulse. When part of the nervous system receives a neural impulse, it may respond by sending another impulse to the appropriate effectors. Many effectors are muscles, which respond by contracting. However, there are many other types of effectors, such as photoreceptor cells or glandular cells. In addition, the nervous impulse may reach another neuron, which triggers it to the next neuron, and so on, although such an impulse may eventually dissipate to the point that it can longer elicit a response from an effector.

II. POST-READING TASKS.

1. Give the definition to the concept “neural impulse” and explain its function.

2. Sum up what you have learned about neurons and prepare a report on the topic: “The neuron is an essential constituent of the central nervous system in organisms of different types”.

UNIT 6

I. PRE-READING AND READING TASKS.

1. Study the meaning and pronunciation of these words:

2. Try to guess the meaning of the following words and phrases:

3. Read and translate the text.