Note on Hormones

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The chemical substance secreted by endocrine and heterocine glands are said to be hormones. They are responsible for the growth and metabolic activities of the targeted cells. As they are those substances who serve as a means of communication among various parts of the human body in a coordinated way, they are known as chemical messengers. The excessive or less production of hormones in our body causes different types of diseases. Some of the major glands and their functions are briefly described below:

  1. Pituitary Gland: A small endocrine gland with the shape and size like a pea is said to be pituitary gland, which lies in the depression of the sphenoid bone inside the skull. It discharges/ secretes stimulating hormones (SH) such as Thyroid Stimulating Hormone (TSH), Antidiuretic Hormone (ADH), Follicle Stimulating Hormone (FSH), Adrenocorticotropic Hormone (ACTH), etc. These hormones help to control the activities of other glands. Hence, it is also said to be a master gland. Growth hormone (GH) which controls growth in humans is also produced by pituitary glands. The under secretion of growth hormone causes dwarfism and oversecretion of this cause gigantism.

  2. Thyroid Gland: The gland which is situated in the neck, one on either side of the upper part of the trachea is said to be thyroid gland. They have the shape of a shield and are bilobed. Thyroid glands secrete thyroxine, which contains iodine and controls general metabolism. The oversecretion of thyroxine causes an increase in the metabolism rate, pulse rate, mental irritability, excessive sweating, and hunger. The under secretion of thyroxine causes retardation of physical and mental growth, dry skin, slow pulse rate and less sweating. This gland also produces calcitonin which encourages calcium deposition in the bone which decreases calcium level in blood.
    The size of the thyroid gland increases due to the deficiency of iodine in the diet, such condition is known as goiter. The condition in which speech becomes slurred and hoarse is said to be cretinism.

  3. Parathyroid Gland: Parathyroid glands are the four tiny glands located on the thyroid gland. The hormone produced by these glands are parathormone which controls the calcium metabolism in the body of humans. The excess secretion of this hormone leads to tumor and stones in the kidneys whereas the less secretion of parathormone leads to tetany.

  4. Adrenal Gland:Adrenal glands are the two glands which are located on the top of each kidney. They are also known as suprarenal glands. The hormones secreted by these glands are epinephrine and norepinephrine which combinedly are known as adrenalin. It is responsible to maintain blood pressure. Generally, it prepares the body to face any emergency situation in case of stress, physical and emotional stress, etc. As it supplies extra energy to face emergency situations, it is also said to be glands of emergency. Adrenal cortex secretes steroid hormone which is called aldosterone that regulates salt balance and hydrosterone that maintains water balance in the body. The excess secretion of adrenalin causes hypertension leading to death.

  5. Pancreas:The heterocine gland which is located in the loop of the duodenum is pancreas. It secrets insulin and glucagon which are opposite in function. Insulin decreases the glucose level in the blood whereas glucagon increases the sugar content in the blood. The low secretion of insulin leads to high level of glucose in blood, hunger, thrist, sugar in urine, weakness, etc. whereas the under secretion of insulin causes slow rate of wound healing process. It shows that the person is suffering from diabetes.

  6. Gonads: Gonads are the heterocrine glands which are the main reproductive organs which are tastes in male and ovaries in female. Testes in male have two main functions: production of sperms and secretion of testosterone, male sex hormone. It promotes the development of masculine secondary sexual characters such as appearance of pubic hair, hoarseness of voice and development of sexual desire. Ovaries in female produces mature ova and female sex hormone oestrogen and progesterone. Oestrogen regulates the development of secondary sexual characteristics and progesterone helps in thickening and vascularization of the uterus and prevention of the uterus from contracting during the pregnancy period.

 Brief Explanation of Hormones and their Functions











a. Growth Hormone

b. Stimulating Hormone

Controls the growth of the body 

Control and stimulate in the secretion of other glands


Dwarfism, More Urination, High B.P., etc..




a. Thyroxine

b. Calcitonin

Growth of the body and stimulates cellular metabolism

Encourage Calcium deposit in bone

Increase in rate of metabolism, Excessive Hunger, etc.

Drying of skin, physical and mental retardation, etc.



Over thyroid 

(Four in numbers)


Maintenance of calcium and phosphate level

Controls the proper development of bones

Formation of tumor and kidney stones




Alimentary Canal (Abdomen)

a. Insulin

b. Glucagon

Maintenance of sugar level in blood

Supplies sugar in blood







a. Adrenalin (Epinephrine and norepinephrine)

b. Aldosterone

c. Hydrosterone

Maintain blood pressure; prepares body to face emergency

Balance salt in body 

Balance water in body





Scrotum (Male: below abdomen)


Develop and maintain male secondary sex characters

Production of sperms


Unable to reproduce 



Reproductive System (Female: Lower part of abdomen)

a. Oestrogen

b. Progesterone

Growth of mammary gland

Growth and development of female secondary sexual characteristics

Prepares uterus suitable for the development of embryo




  1. Hormones are secreted by endocrine and heterocrine glands.
  2. Hormones affect growth and metabolic activities of the targeted cells.
  3. There are three types of glands: exocrine (with duct), endrocrine (ductless) and heterocrine (mixed).
  4. The hormones produced by endocrine and heterocrine glands are considered to be chemical messanger of the body.
  5. Pitutary glands secrets growth hormone and stimulating hormones.
  6. Thyroid gland secrets thyroxine and calcitonin hormones.
  7. Parathyroid gland secrets parathromone hormone.
  8. Pancreas secrets insulin and glucagon.
  9. Adrenal glands secrets adrenalin, aldosterone and hydrosterone hormone.
  10. Testes secrets testosterome.
  11. Ovary secrets oestrogen and progesterone.  

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