Ex. 19. Read text F and be ready to do some tasks.

TASK I. Choose the title for the text:

A. The heart muscle. B. The strongest muscle. C. The muscles of the human body.

TASK II Find the true answer: What muscle is the strongest?

A. The heat muscle. B. The tongue. C. Many different muscles in the human body can be characterized as the "strongest."

TASK III Which statement is true?

Muscular "strength" usually refers to:

A. The power output of the muscle. B. To the weight of the muscle. C. To the ability to exert a force on an external object.

Text F.

Depending on what definition (определение) of "strongest" is used, many different muscles in the human body can be characterized as the "strongest."

Muscular "strength" usually refers to the ability (способность) to exert a force (оказывать усилие) on an external object—for example, lifting a weight.

If "strength" refers to the force exerted by the muscle itself, for example, on the place where it inserts (вставлять) into a bone, then the strongest muscles are those with the largest cross-sectional area. This is because the tension exerted by an individual skeletal (striated) muscle fiber does not vary much, either from muscle to muscle, or with length. Each fiber can exert a force of 0.3 micronewtons. By this definition, the strongest muscle of the body is the Quadriceps femoris or the Gluteus maximus.

Again taking strength to mean only "force" (in the physicist's sense, and as contrasted with "energy" or "power"), then a shorter muscle will be stronger "pound for pound" (фунт 453,6 гр.) (that is by weight) than a longer muscle. The uterus (матка) may be the strongest muscle by weight in the human body. At the time when an infant is delivered (рожать), the human uterus weighs about 1.1 kg.

The external muscles of the eye are large and strong in relation to the small size and weight of the eyeball. It is frequently said that they are "the strongest muscles for the job they have to do" and are sometimes "100 times stronger than they need to be." Eye movements, are very fast (быстрый).

The unexplained statement that "the tongue (язык) is the strongest muscle in the body" appears frequently (часто) in lists of surprising facts, but it is difficult to find any definition of "strength» to make this statement true. Note that technically the tongue consists of sixteen muscles, not one. The tongue may be the strongest muscle at birth.

The heart performs the largest physical work in the course of a lifetime. The power output (производительность энергии) of the human heart range from 1 to 5 watts. This is much less than the maximum power output of other muscles; for example, the quadriceps can produce over 100 watts, but only for a few minutes. The heart does its work continuously for the whole lifetime without pause, and can "outwork" (переработать) other muscles.

Ex.20. Read the article below and answer the question in the title.

What is muscle disease?

The terms ’muscle disease’, ‘muscular dystrophy’, ‘neuromuscular conditions’ and ‘neuromuscular disorders’ all describe a large group of conditions which affect either the muscles, such as those in the arms and legs or heart and lungs, or the nerves which control the muscles. Different conditions affect different muscles.

Most conditions are progressive, causing the muscles to gradually weaken over time. People’s mobility is affected and most conditions lead to some sort of disability. The severity of conditions and how they affect individuals varies greatly from person to person.

Muscle disease affects babies, children and adults, both males and females and all ethnic groups. Conditions are often inherited but can also occur out of the blue where there is no family history.

Ex. 21. Read the article Muscular Dystrophy and retell it in Russian. The words given below will help you in your work.

· genetic = inherited - наследственный

· a pacemaker-вводитель ритма

· to vary-изменяться

· to expect – ждать; expectancy-продолжительность

· to shorten-сокращать.