1. Skeletal growth: Hormones play a role in the growth of cartilage, chondrocytes, osteocytes, osteoblasts, etc.
2. Ion growth: It regulates physical growth by increasing the amount of ions in the body.
3. Enlargement of organs: It increases the size of all the organs of the body except the brain.
4. Abnormal growth: If the hormone is secreted in excess, the person becomes giant and if it is less secreted, the person becomes dwarf.
5. As medicine: Hormones are used as medicine for physical growth of children.
6. Metabolism: Hormones synthesize protein in the body, cause muscle growth, increase glucose and fatty acid levels and prevent body wasting.
7. Production of Red Blood Cells: The hormone stimulates the process of erythropoiesis in red blood cells.
increases the number
8. Milk production: Hormones affect the mammary glands to produce milk. It causes the physical growth of the child.

1. A hormone is a type of biological molecule.
2. It is a protein rich substance.
3. It acts as a biocatalyst.
4. Acts as a chemical messenger in the body.
5. Its action is slow and results are long lasting.
6. It is active at a distance from the place of origin.
7. It is carried through the blood.
8. It is secreted from the endocrine glands.
9. It regulates physical and physiological functions.

The word hormone is derived from the Greek word Hormao meaning to excite. The biochemical substances produced by ductless glands reach various organs through blood and regulate physical and physiological functions are called hormones. British scientists Starling and Bayliss were the first (1905) to use the term hormone. The branch of biology that deals with hormones is called endocrinology.

The alpha (α) cells of the pancreas produce the glucagon hormone and the beta (β) cells produce the insulin hormone. The hormone glucagon increases blood glucose levels and the hormone insulin lowers glucose levels. In this condition, various physical problems arise due to the presence of excess glucose in the blood. It is called diabetes. Many have identified diabetes as the mother of all complex diseases. Diabetes can damage eyes, teeth, liver, heart, kidney, nervous system etc.

The pancreas contains different types of cells. These cell clusters are called islets of Langerhans. It contains alpha cells, beta cells, gamma cells, delta cells, P.P. (pancreatic polypeptide) cells etc. The hormones secreted from this gland are-
(i) Glucagon: Glucagon hormone is secreted from alpha cells. It increases blood glucose levels.
(ii) Somatostatin: Somatostatin hormone is secreted from delta cells. It inhibits gastrin secretion.
(iii) Gastrin: Stimulates the secretion of pepsin, secretin and HCl.
(iv) Insulin: Insulin hormone is secreted from beta cells. It lowers blood glucose levels.

In infants, the thymus gland is located in the mediastinum cavity in front of the trachea. It becomes smaller and eventually disappears with age.
(i) Thymochrysin hormone: This hormone produces antibodies, prevents sexual maturation and childhood diseases.
(ii) Melatokinin hormone: It stimulates melatocyte cells.

It is secreted in the oval gland and diencephalon of the brain. It is an inactive gland in the human body. Melatonin hormone is released from this gland. This hormone causes penis enlargement.

Ovary is the main organ of female reproductive system. Three types of hormones are secreted from the ovaries.
(i) Progesterone: Progesterone hormone is secreted from the corpus luteum.
(ii) Relaxin: Relaxin hormone is secreted from bile glands. It prevents uterine contractions.
(iii) Estrogen: There are three types of estrogen. Estradiol, estrone and estriol. It causes symptoms in women. Increases mammary glands. Body softens the skin.

The main organ of the male reproductive system is the testes. Its number is 2. It is oval. Two types of hormones are secreted from the testicles.
(i) Testosterone: It produces sperm.
(ii) Androsterone: It produces sperm.

Each kidney has a cap-like yellow adrenal gland. Its other name is suprarenal gland. It consists of two parts. Cortex and medulla. Each gland weighs 3-5 grams.
(i) Glucocorticoid hormone: This hormone regulates sugar metabolism.
(ii) Mineralocorticoid hormone: This hormone metabolizes mineral salts.
(iii) Sex corticoid hormone: It causes genital growth and sexual symptoms.
(iv) Adrenaline hormone: This hormone increases heart rate and helps in times of danger.
(v) Nor-adrenaline hormone: It accelerates the metabolism of phosphorus.
(vi) Epinephrine hormone: It releases glucose from glycogen. Controls cardiac and involuntary muscle contractions.
(vii) Nor-epinephrine hormone: It converts excess glucose into glycogen.