Unit 10 The Evolution of Hormones

Introduction

I. In pairs check the Russian translation of the words and phrases below.

peptides amino-acid derivatives

steroids prostaglandins

target cells bind to receptors intracellular second messengers

cyclic AMP diffuse through the plasma membranes

the hormone-receptor complex the transcription of specific genes.

thyroid hormones negative feedback

to inhibit further secretion of hormone the mammalian endocrine system

clusters of cells a network of capillaries

the thyroid and parathyroid glands the pancreas

the adrenal glands the pineal gland

thymus the hypothalamus – pituitary complex

Now listen to the summary of key concepts concerning the endocrine system of the animal body, make notes and get ready to retell it.

II. Give your own definitions to the following words. Read the definitions to your partner. Can he/she guess the word defined?

amino acid

blood

cyclic AMP

hormone

kidney

pineal [pınıəl] gland

small intestine

target cell

thyroid [Өaıro:ıd] gland

III. In the USA some parents who are interested in college sports scholarships for their children are asking physicians to prescribe growth hormone treatments. Farmers also have an economic incentive to treat cows with growth hormone, which can now be produced in large quantities by genetic-engineering techniques. What biological and ethical problems do you foresee for parents, children, physicians, coaches, college scholarship boards, food consumers, farmers, the U.S. Food and Drug Administration, and biotechnology companies?

Reading

I. Look through the text. Put all the paragraphs in order.

A B C D E

The Evolution of Hormones Thyroxine regulates the seasonal molting of most vertebrates. From snakes to birds to the family dog, surges of thyroxine stimulate the shedding of skin, feathers, or hair. In humans (who neither migrate regularly, metamorphose, nor molt), thyroxine regulates growth and metabolism. The use of chemicals to regulate cellular activity is extremely ancient. The diversity of life on Earth rests upon a conservative foundation: a relative handful of chemicals coordinate activities within single cells and among groups of cells. Life’s diversity originated in part by changing the systems used to deliver the chemicals and by evolving new types of responses. Early in their evolution, animals developed a complemented to hormonal communication that provides faster, more precise delivery of chemical messages: the nervous system. The nervous system permits rapid responses to environment stimuli, flexibility in response options, and ultimately consciousness itself. Not long ago, vertebrate endocrine systems were considered unique to our phylum, and the endocrine chemicals were thought to have evolved expressly for their role in vertebrate physiology. In recent years, however, physiologists have discovered that hormones are evolutionarily ancient. Insulin, for example, is found not only in vertebrates but also in protists, fungi, and bacteria, although research has not yet determined the function of insulin in most of those organisms. Protists also manufacture ACTH, even though they have no adrenal glands to stimulate. Yeasts have receptors for estrogen but no ovaries. Thyroid hormones have been found in certain invertebrates, such as worms, insects, and mollusks, as well as in vertebrates. Even among vertebrates, the effects of chemically identical hormones, secreted by the same glands, may vary dramatically from organism to organism. Let’s look briefly at the diverse effects that the thyroid hormone thyroxine has on several different organisms. In amphibians, thyroxine has the dramatic effect of triggering metamorphosis. In 1912, in one of the first demonstrations of the action of any hormone, the tadpoles were fed minced horse thyroid. As a result, the tadpoles metamorphosed prematurely into miniature adult frogs. In high mountain lakes in Mexico, where the water is deficient in the iodine needed to synthesize thyroxine, natural selection has produced one species of salamander that has the ability to reproduce while still in its juvenile form. Some fish undergo radical physiological changes during their lifetimes. A salmon, for example, begins life in fresh water, migrates to the ocean, and returns to fresh water to spawn. In the stream where the salmon hatched, fresh water tends to enter the fish’s tissues by osmosis; in salt water, the fish tends to lose water, becoming dehydrated. The salmon’s migrations, therefore, require complete revamping of salt and water control. In salmon, one of the functions of thyroxine is to produce the metabolic changes necessary to go from life in streams to life in the ocean and back.

II. Give a summary in writing of the final version of the text.

Language focus 1

Should: Obligation, Degrees of Certainty

1 We often use should to talk about obligation, duty and similar ideas. It is less strong than must.

Everybody should wear car seat belts.

Applications should be sent before December 30^th.

In questions, should is used to ask for advice or instructions:

Should I go and see the police, do you think?

What should we do?

2 We can use should to say that we know something is probable (because it is logical or normal in the circumstances).

She’s away but she should be back tomorrow. (= I have good reasons to believe that she will be back tomorrow.)

We’re spending the winter in Florida. – That should be nice. (It is about 70% likely.)

3 should have done

It can be used to talk about past events which did not happen, but which were planned or supposed to happen. It is also used to express criticism. (Someone didn’t do it but it would have been the right thing to do.)

I should have phoned Ed this morning, but I forgot.

Ten o’clock: she should have arrived in the office by now.

I. Translate into English.

1. Сейчас весна. Все должны принимать витамины.

2. Результаты будут готовы к вечеру.

3. Нам не стоило уезжать в отпуск, пока эксперимент не закончен.

4. Мне стоит сесть на диету?

5. Тебе следовало позаботиться об этом заранее!

Language focus 2

Should, Ought to, Must

1 Should and ought to are very similar: they are both used to talk about obligation and duty, to give advice; also, ought to, like should, is used to talk about probability. Should is much more frequent than ought to.

You should / ought to see ‘Daughter of the Moon’ – it’s a great film. (advice)

I’ve bought three loaves – that should / ought to be enough. (The speaker is 70% sure.)

Ought is always used with to:

You ought see this film. – This is INCORRECT.

2 Must is stronger than should/ought to.

Must has similar meanings to should and ought, but is stronger or more definite. It expresses greater confidence that something will happen, or that something is true; should and ought to express less confidence. Compare:

- The doctor said I must give up smoking. (An order which the patient most probably will obey.)

You really ought to give up smoking. (A piece of advice which may or may not be followed.)

- Rob must be at home by now. (= I’m sure he is at home.)

Rob should be at home by now. (= I think he is probably at home.)

Should can be used instead of must to make instructions more polite.

This form should be filled in ink.

3 Should have done and ought to have done can be used to talk about unfulfilled obligations in the past. Must is not used like this.

You ought to/ should have been nicer to Annie. (BUT NOT You must have been nicer to Annie.)

I. Translate into English.

1. Тебе не следовало разговаривать с ней таким тоном.

2. При обнаружении бесхозных вещей обратитесь к водителю.

3. Эксперимент должен быть завершен к апрелю.

4. К опыту нужно готовиться более тщательно.

5. Если ты встретишь Ника, тебе стоит пригласить его в клуб.

II. Use the following word combinations in situations of your own.

1. It shouldn’t be difficult to…

2. … so she should pass.

3. You should have come. Why… ?

4. … . I shouldn’t have eaten so much….

5. Do you think I ought to …

6. “Should we… ?” – “Yes, I think we should”.

7. The government should…

8. You look tired. You should…

Words, Words, Words

I. Think through the topic of the unit and choose the right answer.

1 Steroid hormones

a. alter the activity of genes

b. trigger rapid, short-term responses in cells

c. work via second messengers

d. initiate open channels in plasma membranes

e. bind to cell-surface receptors

2 Examples of posterior pituitary hormones are

a. FSH (follicle-stimulating hormone) and LH (luteinizing hormone)

b. prolactin and parathormone

c. secretin and cholecystokinin

d. melatonin and prostaglandin

e. ADH (antidiuretic hormone) and oxytocin

3 Negative feedback to the hypothalamus controls the level of _____________ in the blood.

a. thyroxine

b. estrogen

c. glucocorticoids d. insulin

e. all of the above

4 The primary targets for FSH are cells in the

a. hypothalamus

b. ovary

c. thyroid gland

d. adrenal medulla

e. pituitary gland

5 The kidney is a source of

a. thyroxine and parathormone

b. calcitonin and oxytocin

c. renin and erythropoietin

d. ANP (atrial natriuretic peptide) and epinephrine

e. glucagon and glucocorticoids

6 Hormones that are produced by many different body cells and cause a variety of localized effects are known as

a. peptide hormones

b. parathormones

c. releasing hormones

d. prostaglandins

e. exocrine hormones

II. Match the words in column A with their definitions in column B and translate them into Russian.

A 1 homeostasis 2 salivary gland 3 pituitary gland 4 retina 5 endocrine gland 6 hypothalamus 7 negative feedback

B a a multilayered sheet of nerve tissue at the rear of camera-type eyes, composed of photoreceptor cells plus associated nerve cells that refine the photoreceptor information and transmit it to the optic nerve b a situation in which a change initiates a series of events that tend to counteract the change and restore the original state. Negative feedback in physiological systems maintains homeostasis c a ductless, hormone-producing gland consisting of cells that release their secretions into the extracellular fluid from which the secretions diffuse into nearby capillaries d an exocrine gland that releases saliva into the mouth e a region of the brain that controls the secretory activity of the pituitary gland; synthesizes, stores, and releases certain peptide hormones; directs autonomous nervous responses f an endocrine gland, located at the base of the brain, that produces several hormones, many of which influence the activity of other glands g the maintenance of a relatively constant environment required for the optimal functioning of cells, maintained by the coordinated activity of numerous regulatory mechanisms, including the respiratory, endocrine, circulatory, and excretory systems

Language focus 3

Other Uses of Should

1 It’s important that… should…

In formal British English, should can be used after: It is important (necessary, vital, essential) that…

It’s important that somebody should talk to the police.

Is it necessary that my uncle should be informed?

This also happens after some verbs expressing similar ideas of importance of an action, especially in sentences about the past.

He insisted that the contract should be read aloud.

I demanded that he should apologize.

In a less formal style, other structures are preferred.

It’s important that she talks to me when she gets here.

Was it necessary to tell my uncle?

2 After the verb to suggest three constructions are possible:

I suggest that you should stop the experiment.

I suggest that you stop (he stop, we stop) the experiment.

I suggest that he stops the experiment.

I. Translate into English.

1. Преподаватель рекомендовал, чтобы студенты прочитали дополнительно два источника.

2. Я предлагаю, чтобы вы тоже участвовали в исследовании.

3. Важно, чтобы все красители соответствовали нормативам.

4. Желательно, чтобы ученый совет (Science Board) настаивал на продолжении эксперимента в течение следующего семестра.

5. Странно, что ты пьешь так много кофе вечером.

II. Write a sentence that means the same as the first sentence.

1. ‘I think it would be a good idea to do some more exercises,’ the teacher said to us.

The teacher said that ………………………………………………………………

2. ‘You really must pay more attention to the accuracy of your calculations,’ she said to me.

She insisted that …………………………………………………………………...

3. ‘Why don’t you eat your apple after the lesson?’ I said to him.

I suggested that ……………………………………………………………….……

4. ‘You must complete your term paper by March,’ my scientific supervisor said to me.

The scientific supervisor demanded that …………………………………………..

III. Are these sentences correct or incorrect?

1 a Mary suggested that I should look for another job. C / I

b Mary suggested that I look for another job. C / I

c Mary suggested that I looked for another job. C / I

d Mary suggested me to look for another job. C / I

2 a When do you suggest I go on a business trip? C / I

b When do you suggest me to go on a business trip? C / I

c When do you suggest I should go on a business trip? C / I

Render in English.

Железы как эффекторные органы

Секрет слюнных, слезных и многих других желез проходит (часто по специальным протокам) очень короткий путь от места образования до места действия. В отличие от этого гормоны, синтезирующиеся в лишенных протоков эндокринных железах, разносятся с током крови часто в самые отдаленные уголки организма.

Гормональная регуляция различных процессов в организме служит дополнением к нервной. Вообще говоря, нервные импульсы вызывают ответы значительно быстрее, чем гормоны, но эндокринные влияния более длительны и всеобъемлющи.

Гормоны позволяют организму реагировать на изменения внешней и внутренней среды. Некоторые гормоны регулируют постоянство состава жидких сред организма. Для того чтобы подобные гомеостатические механизмы функционировали нормально, гормоны должны поступать в кровь только тогда, когда в них возникает необходимость. Секреция таких гормонов регулируется по принципу отрицательной обратной связи, то есть является процессом, который автоматически ограничивает собственное развитие.

Но секреция гормонов может происходить и в ответ на изменения во внешней среде. Многие животные, например, маскируются, изменяя свою окраску в зависимости от фона. Этот процесс связан с изменением размеров хроматофоров – клеток кожи, содержащих различные пигменты; в результате меняется цвет и характер окраски всего животного. У некоторых рыб, амфибий и рептилий характер световых стимулов, достигающих сетчатки, контролирует выброс гипофизом меланоцитстимулирующего гормона, а этот гормон, в свою очередь, вызывает изменение размеров хроматофоров.

Каким же образом органы чувств, реагирующие на изменения внешней среды, связаны с железами внутренней секреции, например, с гипофизом? В качестве посредника в данном случае выступает нервная система, собирающая информацию от органов чувств и передающая ее в жизненно важную область мозга – гипоталамус. Группы клеток гипоталамуса обусловливают ответы на такие ощущения, как боль, удовольствие, чувство голода или жажды и сексуальную потребность. Гипоталамус связан с другими участками нервной системы, а также с гипофизом – важнейшей эндокринной железой, в которой синтезируется множество гормонов. Каждый из этих гипофизарных гормонов вызывает изменения в деятельности одного или нескольких органов.