How does Endocrine System Affect Behaviour?

This article will guide you about how endocrine system affect behaviour of an individual.

The glands along with the muscles constitute the ‘effector’ organs. The various glands in the human body secrete various chemical substances necessary for growth and maintenance functions.

These glands are of two broad types. One type of glands secrete chemical substances which are carried to different parts of the body through tubes or ducts, e.g.. the tear glands. These are called duct glands or exocrine glands.

The other types of glands deliver their secretions directly into the blood stream without the help of ducts and tubes. These are known as ductless or endocrine glands. These glands secrete chemical substances known as hormones. Hormones are directly involved in our metabolic processes and also in stimulating growth.


They are very important in rendering our behaviour normal or otherwise. The endocrine glands, by themselves, do not initiate any specific activity but influence and modulate the other activities. The different endocrine glands are functionally influenced by each other and act as a system. Thus, the activation of one gland like the pituitary, for example, tends to inhibit the activities of other endocrine glands.

This is why we speak of an endocrine balance. It refers to a pattern of endocrine functioning where the different glands have developed and function optimally. Basically the endocrine system functions towards the maintenance of homeostasis or maintenance of the chemical equilibrium of the body. The endocrine system is under the control of the central nervous system.

This chemical equilibrium may be disturbed either by over activity or under activity of the endocrine glands. Such an imbalance can result in psychological abnormality or physical abnormality or both. The former may involve changes in temperament, intelligence and emotional state, while the latter may involve the appearance of secondary sex characteristics, change in the rate of growth etc. Physical abnormalities, in turn, may produce behavioural abnormalities of a secondary nature. The endocrine glands can be categorized into major and minor glands.

The major endocrine glands, their secretions and functions are briefly considered below:


1. The Pituitary:

The pituitary glands located below the brain, this is a very important gland and is thought of as the master gland. It regulates and controls the other endocrine glands, and is responsible for the regulation of growth and other associated physiological activities. It secretes pitutrin and other hormones. Under-activity of the pituitary gland leads to dwarfism. Deficiency during the pre-pubertal stage can give rise to midgets. Over activity during the growth period results in gigantism. Over activity during adulthood results in a condition called acromegaly.

2. The Thyroid:

The thyroid glands produce thyroxin or iodine and they are responsible for the rate of living activity. They influence metabolic rate, growth and development. Thyroid deficiency in infancy leads to cretinism or feeblemindedness. Thyroxin of poor quality leads to a condition known as colloid goitre or enlargement of the gland.

Thyroid deficiency in adulthood leads to a condition referred to as myxedema which is characterised by overweight and general sluggishness. Thyroid over secretion leads to a condition known as Grave’s disease which is characterised by accelerated metabolic processes.

3. The Parathyroids:

The parathyroids regulate calcium and phosphorous metabolism and are responsible for the bony structure of the body. Removal or destruction of the parathyroids leads to a condition called tetany and is marked by excited nervous system.

4. The Adrenals:

The adrenals are very important glands and they regulate the physiological and psychological functioning. The adrenal medulla secretes adrenalin and noradrenaline also known as epinephrine or norepinephrine which affect neural functioning and bodily changes in emotions, especially during emergencies, and emotions like fear, rage and anger.

The adrenal cortex secretes steroids which affect body activity, metabolism, influence stress reaction and the development of secondary sex characteristics. Deficient secretion of steroids results in Addison’s disease which is characterised by increased fatigue, loss of appetite, anaemia, irritability, restlessness, sleeplessness, weakness and darkening of skin.

Its excessive secretion leads to what is described as Gushing’s syndrome characterised by muscle weakness, decreased sex drive, fatigue and disfiguring bodily changes. Hyper secretion of steroids also known as corticoids in a male leads to ‘feminism’, i.e. development of female characteristics.

Over secretion of corticoids in a female leads to ‘virilism’ or the development of male characteristics. Hyper secretion of corticoids in a child leads to ‘puberty praecox’ i.e. early sexual maturity. For example the chronological and mental age may be 6 years but the sexual maturity may be that of a 16 year old.

The Endocrine System

5. Gonads:

Gonads are vital to sexual development and reproduction. The gonadal hormones, estrogen and progesterone in females and androgens or testosterone in males, are generally responsible for sex characteristics, sex drive, sexual behaviour and sexual motivation. Gonadal dysfunction may lead to severe psychological problems.

Castration of male before puberty results in eunuchism. Deficiency during development or insufficient gonadal hormone production during childhood results in the failure to develop appropriate secondary sexual characteristics and sex drive.

Marked reduction of gonadal hormone production in females and males during middle age results in conditions known as menopause and period, respectively and this may cause irritability, restlessness, anxiety, insomnia, depression etc. The pineal body, the thymus and pancreas are other endocrine glands. These, however, are not as significant from the point of view of psychology as those discussed above.

The analysis of the functions of the endocrine glands should make obvious to the reader the significant role of the endocrine system in behaviour. Many forms of abnormal behaviour are found associated with endocrine malfunction, but this should not cause the reader to conclude that endocrine abnormality is an invariable factor in the causation of abnormal behaviour.

It has been found that other factors like malnutrition can also often produce effects very similar to those resulting from endocrine malfunctioning. The existence of endocrine malfunctioning should be assumed only when evidenced by appropriate clinical investigations.

In this article we have mainly emphasised the nervous and the endocrine systems. This does not mean that the other organs of the body are not related to behaviour. Other systems like the skeletal system, the muscular system and the reproductive system also have their obvious roles in behaviour. The only difference is that the nervous system and the endocrine system are, in a way, general systems which are much more inclusive and comprehensive in their operations. They have their impact on all the other systems.

In the early stages of modern psychology there was a tendency to reduce all behavioural processes to bodily processes.

Later, with the advances in depth psychology, particularly psychoanalysis and humanistic psychology, there was a trend to move away from this reductionism of psychological processes to bodily processes. More recently, however, with advances in knowledge in the fields of neurosciences, endocrinology, psychopharmacology, biochemistry and other fields we are able to understand the more intricate relationships between body processes and behaviour.

This may tempt the reader to jump to the conclusion that ultimately all behavioural processes could be reduced to body physics, body chemistry and so on. In fact, years ago John Stuart Mill spoke of mental chemistry.

More recently even outstanding psychologists like Clark Hull have visualised such a possibility though admittedly remote. But the question is whether this possibility will be a real one as we begin to understand more and more about behaviour itself. Understanding the bodily processes may help us to explain some of the past mysteries about behaviour, but the field of behaviour is so full of mysteries that we may probably never reach a stage when all of them will be adequately explained by unraveling the working of the body. Perhaps, the question itself has been wrongly put.

Can we consider the body and mind as separate entities? What appears to be relevant is neither dualism nor monism but the organism. The problem arose because the body and mind were considered as two different entities put together but in reality probably this distinction was wrong. The problem seems to be very similar to the distinction made in classical physics between matter and energy. The physicist today is no more bothered about this distinction.

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