Hormones & Their Effects

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More Hormones - Growth Hormones

A. Growth Hormone

Growth is a complex process and requires the coordination of several hormones of which the main one is growth hormone. It is produced by the pituitary gland and acts on the liver, stimulating it to produce another hormone. It is this second hormone, which directly affects the growth of bone and muscle. Growth hormone also helps to control the body´s use of proteins, carbohydrates and fats.

Babies´ length, mass and head size are routinely measured during the first few months of life. Growth problems may be highlighted when the results are plotted on Average Growth Charts, although such charts are used only as a guide.

Growth Hormone Deficiency

In children, if there is not enough growth hormone, growth does not happen at the normal rate and this can result in dwarfism. The treatment for this deficiency is to give the child growth hormone which, nowadays, is produced by genetic engineering.

Excessive secretion of Growth Hormone

Two brothers stand next to each other. One brother is average height and the other is exceptionally tall.

Robert Wadlow in 1936 next to his brother

Photo used with permission of
The (Alton, IL) Telegraph

If too much growth hormone is produced in childhood, then giantism results. The most famous case of giantism is that of Robert Wadlow. He weighed a normal 8.5 pounds at birth but by 5 years of age he weighed 7.5 stones and was 5 ft 4 tall. As an adult he weighed 35 stones and was 8 ft 11 tall. He died aged 22 years.

Extremes in height (dwarfism and giantism) can also be inherited from parents in the genes.

Too much growth hormone in adults results in a disease called acromegaly in which there is an overgrowth of bone giving the person a change of appearance. This happens slowly over a long period of time.

The Future for Growth Hormone

Genetic engineering means that there is a plentiful supply of growth hormone for everyone who needs it. Growth hormone might have a role in anti-aging treatments and this is being researched at present. The cow version, bovine growth hormone, and the pig version, porcine growth hormone, have been used in animals to increase yields of milk and of leaner meat without any harmful effects on humans who eat the meat.

Question 6

Study the growth characteristics in the charts above then answer the following questions:

Which child's height is above average?

Which child's height is average?

Which child's height is below average?

Which child seems to have significant growth problems?

Study the sentences below, then drag and drop
the missing words to complete the sentence.

Dwarfism is a result of too

growth hormone.

little

much

Growth hormone is produced by the

hypothalamus

pituitary

Robert Wadlow had too

growth hormone.

little

much

Acromegaly is a disease in

adults

children

Bovine growth hormone comes from

pigs

cows

Hormone

A chemical messenger produced by a particular gland or cells of the endocrine system. Hormones are transported throughout the body in the blood stream but they produce a response only in specific target cells.

Pituitary gland

An endocrine gland attached to the hypothalamus which has two lobes. The posterior lobe secretes several different hormones whereas the anterior lobe just stores and releases one particular hormone.

Liver

A large organ in the upper abdomen which manufactures, stores and breaks down substance as required by the body.

Protein

A polymer made up of amino acids joined by peptide bonds. The amino acids present and the order in which they occur vary from one protein to another.

Carbohydrate

Energy producing organic compounds which are made of carbon, hydrogen and oxygen. Examples of food containing carbohydrate are rice, pasta, bread and potatoes

Dwarfism

A lack of growth hormone in childhood results in a failure of the long bones to grow and in an adult of short stature.

Genetic engineering

A general name for the processes which scientists use to produce desired characteristics or substances that are in short supply, such as human growth hormone. Genes are taken from human cells and can be put into bacteria, which reproduce very quickly, and so can produce large quantities of a desired substance.

Giantism

Over-growth of the long bones caused by too much growth hormone being produced in childhood.

Gene

A short piece of DNA which is responsible for the inheritance of a particular characteristic. It codes for the production of a specific protein.

Acromegaly

The abnormal growth of bone in the hands, feet and face caused by over-production of growth hormone in adulthood