What are hormones?
A hormone is a chemical substance secreted by endocrine glands of our body. These are released or secreted by these glands in the blood stream and thus flow throughout the body and work on their target organs. These help in the chemical coordination and proper functioning of the body.
Hormones are secreted by endocrine glands, for example- pineal gland, pituitary gland, thyroid gland, adrenal gland, pancreas, thymus, parathyroid glands and gonads. Even the heart, liver and kidneys secrete hormones.
The secretion of hormones is majorly regulated by the Hypothalamus. It controls the hormones of the pituitary.
The anterior pituitary secretes hormones such as-
1. Growth hormone (GH) –
its uncontrolled level can cause gigantism and acromegaly whereas its deficiency can lead to dwarfism
2. Prolactin (PRL) – regulation of growth of mammary glands
3. Thyroid stimulating hormone – acts on the thyroid gland
4. Luteinizing hormone – acts on gonads of males
5. Follicle stimulating hormones – acts on gonads of females
The posterior pituitary secretes hormones such as-
· it secretes T<sub>3</sub> (triiodothyronine) and T<sub>4</sub> (thyroxine)
· deficiency of thyroid hormones causes hypothyroidism and goitre
· increase in the levels of these hormones causes hyperthyroidism
· it regulates the calcium levels of bones and blood
· takes up extra Ca<sup>2+</sup> ions from the bones and releases it in blood
· adrenal cortex- hormones secreted through these regulate carbohydrate metabolism
· its deficiency leads to Adison’s Disease
· adrenal medulla – secretes hormones such as epinephrine and norepinephrine
· these help in flight or fight, that is, running away in times of danger or facing them
· these secrete hormones through 3 types of cells
· alpha cells- secrete glucagon
regulates blood glucose levels:
increase of blood sugar causes hyperglycemia
deficiency causes- hypoglycemia
· beta cells- secrete insulin
these also regulate blood glucose levels
their deficiency causes diabetes mellitus
· delta cells- secrete somatostatin
· testis are situated in the scrotal sac of man
· these secrete androgens – testosterone
· testosterone acts for the development of male accessory organs, secondary sexual characters
· it regulates the formation of sperms
· the primary sex organ of female
· it secretes estrogen and progesterone
· estrogen helps in the development of mammary glands., female secondary sexual characters and regulates the formation of follicles
· progesterone acts during pregnancy
to sum up, hormones play major roles in our body and life. Without these messengers our body would not work efficiently. A healthy diet plays an important role in their regulation. Their deficiencies, if detected early, can treated by using supplements prescribed by the doctor.