METHOD OF STUDY OF ENDOCRINE GLANDS - PowerPoint Presentation

Slide1

METHOD OF STUDY OF ENDOCRINE GLANDS

LECTURER IN CHARGE

BAMIDELE OLUBAYODE

DEPARTMENT OF PHYSIOLOGY

BOWEN UNIVERSITY, IWO, NIGERIA

INTRODUCTIONThe study of endocrine glands is essential in the field of endocrine Physiology.

It gives information on how endocrine organs function.

The study of endocrine glands include the following methods:

Anatomical method

Biochemical method

Physiological method

Clinical Method

Anatomical MethodThis involves the study of the following:

Location of the organ

Its division and parts

Histology

Nerve supply

Blood supply

Biochemical MethodIt involves the study of the:

chemical constituents of the hormones synthesized by the glands

chemical stucture of the hormone produced by the glands.

half life:It is also called biological half­life. Half­life

of a hormone denotes the elimination of that hormone

from circulation.

ways by which the hormones are formed

Physiological MethodsThis includes the study of the:

hormones secreted by the glands.

actions of the hormones

The evidence to support the functions of the glands is either by

augumenting

or

decreasing

the various ways the function in question.

Physiological Method cont'd

Several methods of

augumeting or increasing

the hormone content in the blood include the following:

administration of extract or the hormone of the gland

grafting into the body viable endocrine tissue

stimulation of their secretory nerve

Physiological Method cont'd

Functional deficiencies (

decrease in hormone secretion

) can be created by:

extirpation (removal) of the gland

injecting substances to cause bland infarct in the glands

ligating the blood vessels supplying the organ in question

Administration of Extract or the Hormone of the Gland

Experiments with gland extracts are complicated by the fact that in addition to specific hormones, various more or less potent non-specific substances may be present.

When given by mouth these substances ar

e

relatively unimportant but when the extracts are introduced by vein they often play a predominant role in the reactions.

This could produce overactivity of the hormone when this is done in normal gland.

Grafting into the body viable endocrine tissue

In some instances organ grafting has been used to augment the quantity of circulating hormones.

In the early development of the thyroid treatment of myxedema this procedure was successfully employed.

There are numerous technical difficulties, however, which limit the use of the method in practical experimentation.

The only way in which grafting can be accomplished with anything

like constant success is by the employment of the individual's own tissues (autografting)

.

.

Grafting into the body viable endocrine tissue

The more closely related are the host and the donor of the tissue the more likely is the graft to "take."

Transference from one species to another (heterografting) is prac

t

ically never successful.

Stimulation of their Secretory Nerve

In some respects stimulation of the secretory fibers to a given gland is the most satisfactory method of augmenting the amount of the corresponding hormone.

The secretion thereby secured is supposedly normal in quality and not greatly outside physiologic limits in quantity.

For this among other reasons, a definite knowledge of the secretory innervation of all the endocrine organs is needed.

Extirpation (removal) of the Gland

This is the removal of the gland to cause deficiency in the synthesis of the hormone of the gland.

It can be done surgically or by burning off the gland (ablation).

The method is particularly adapted to investigate the problem as to what glands are essential to life.

But even in this case concordant results have not in all

instances been secured.

Extirpation (removal) of the Gland

For example, Cushing maintains that complete removal of the pituitary gland is inevitably fatal while Aschner, another skilled scientist, is equally sure that animals may survive the operation.

One maintains that death following extirpation of the gland is due to incidental trauma; the other that survival when it occurs is to be ascribed to bits of gland left behind in the operation.

Injecting substances to cause bland infarct in the glands

Bland infarcts can be

formed

by injecting fine suspensions of inert insoluble material into the arteries leading to different glands.

Tobacco seeds or lycopodium spores are most commonly

used

.

This process involves comparatively little trauma and can be regulated to produce various grades of deficiency.

It is a method, however, somewhat difficult to control. So far it has not led to any striking results

.

Ligating the Blood Vessels Supplying the Glands

Ligating the blood vessels supplying the glands is one of the methods used clinically and experimentally to decrease their functions.

It is a well known method of treating exophthalmic goitre in patients who are in a serious condition to undergo thyroidectomy.

Experimentally the method in most cases is unreliable. Small vessels may remain untied and become enlarged or cappillaries may grow into the surrounding tissues in the anemic area and vascularised it so the part of the gland can hypertrophy and continue to function.

Clinical Method

This involves the clinical observation of the patients for hormone disorders.

The disorders may be due to oversecretion or undersecretion of the hormnes.

For example, Addison's discovery that deficiency of the suprarenal glands results in muscular and circulatory weakness remains as probably the most significant information yet offered bearing on the physiology of these glands.

A similar statement may be made in regard to the discovery of the relation of the thyroid glands to myxedema and cretinism.

References

Sembulinga, K.

Essentials of Medical Physiology. Sixth Edition.

Endocrinology. Methods of investigating endocrine functions.

Thank you for your attention

Hope you stay safe