The most important endocrine glands in the human body

Most important endocrine glands

They are the glands of the endocrine system which secrete their hormones directly into the blood rather than through the duct , The main glands of the endocrine system include the pineal gland , Pituitary gland , Pancreas , Two ovaries , Two testes , Thyroid gland , Parathyroid gland , Hypothalamus and the adrenal glans .

The gland is a group of cells which produces and secretes or gives off chemicals , The gland selects and removes the materials from the blood , processes them , and it secretes the finished chemical product for use somewhere in the body .

Endocrine glands

Endocrine glands

Thyroid gland

Thyroid gland is located in the front surface of the neck on both sides of the trachea , It consists of two lobes , linked together by a small part , It secretes two hormones which are Thyroxin hormone and Calcitonin hormone .

Thyroxin hormone plays a main role in food assimilation processes in the body , where it liberates the energy necessary for the human body from the food , Calcitonin hormone controls the level of calcium in the blood .

There are four parathyroid glands that are embedded in the rear surface of Thyroid gland , It controls many body functions including the heart rate , the temperature and the metabolism , These glands play a role in the metabolism of calcium in the body .

Some diseases resulted from the thyroxin hormone disorder in the human body
Simple goiter

Simple goiter is the enlargement of thyroid gland and the neck , Its reason is the decrease in the Thyroxin hormone secretion , the decrease of iodine from the diet causes the decrease in the secretion of the Thyroxin hormone  , because iodine  enters in the hormone’s structure .

Simple goiters are more common in the people over age 40 , the people with a family history of goiter & in the women , The main symptom is the enlarged thyroid gland , The size may range from the single small nodule to the  large mass at the front of the neck .

Exophthalmic goiter

It is the enlargement of thyroid gland accompanied by loss of the weight , the tension and the exophthalmoses , If the thyroxin hormone secretion is increased in great amounts , It will cause the exophthalmic goiter .

Adrenal glands

Adrenal glands are located adhering by the top of the kidney , The adrenal glands secrete the adrenalin hormone which stimulates the body’s organs to respond to the  emergencies .

Each of the adrenal glands weighs about 4 grams and it is about the size of your thumb , They are situated just above the kidneys and they consist of two parts , the adrenal medulla and the adrenal cortex , They produce the hormones that are essential for the life and they help us cope with the stress .


The pancreas is located between the small intestine and the stomach , It secretes two hormones which are Insulin hormone and Glucagon hormone , Insulin hormone reduces the blood sugar level by transporting glucose sugar from the blood cells which use it to release the energy , and by storing glucose sugar that increases in the body in liver .

Glucagon hormone raises the level of sugar in the blood by stimulating liver to convert the stored glycogen into glucose that releases into the blood stream to be available to the body cells , ( Its function contradicts the function of Insulin hormone .

The pancreas is a double function gland because the pancreas acts as ductless gland which secretes the insulin and glucagon hormones that regulate the glucose sugar level in the blood and it also secretes the digestive enzymes that help in the digestion process through a duct .

The disease that is resulted from the insulin hormone disorder in the human body

Diabetes is due to the insulin hormones disorder , Diabetes symptoms are feeling thirsty and multiple urination times , Diabetes is due to the decrease in the secretion of the insulin hormone which leads to increasing the level of glucose sugar in the blood , as a result of the cells are unable to use glucose .

Two testes

The two testes secrete the testosterone hormone which is responsible for the appearance of the male secondary sex characters , They are situated in a pouch that hangs outside the male body , Two testes produce the hormones necessary for the production of the sperm and the other male sexual characteristics .

Two ovaries

Two ovaries secrete two hormones which are Estrogen hormone and Progesterone hormone , Estrogen hormone is responsible for the appearance of the female secondary sex characters , Progesterone hormone promotes the growth of endometrium ( The lining of uterus ) .

The two ovaries are situated either side of the uterus , They contain the egg cells , And they are necessary for the reproduction process , they produce the estrogen and progesterone that are necessary for the menstruation and they produce the other female sexual characteristics .

The female vocal cords produce voices louder than those produced by male ones , This is because the sexual hormones in the mature male body cause an increase in the thickness of vocal cords , So , the thin vocal cords in a female’s larynx vibrate faster than the thick vocal cords in the male’s larynx .

Endocrine system , Endocrine glands , Pituitary gland & Hormonal coordination in living organisms

Thyroid gland , Diseases of thyroid gland & Function of Parathyroid glands

Adrenal ( suprarenal ) glands , Pancreas & Sex glands ( Gonads )

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