Hormones are chemical messengers that help to maintain a balance between various life processes, including metabolism, sugar regulation, temperature regulation, and mood changes. There are various hormones released prior to birth that coordinate in the process of development of bones, teeth and muscles.¹

Each of hormones its unique functions for the overall maintenance of the body. The most important hormones including:

1. Insulin 
2. Thyroxine
3. Cortisol
4. Estrogen
5. Testosterone

Hormones usually function in 2 ways:

• Indirect action- Hormones stimulate other organs to release hormones that act to complete the accompanied task
• Direct action- Hormones released, involve themselves in the action²

Release of hormones-

The release of hormones takes place with positive and negative feedback.

• Presence of one element in the blood stimulates the release of certain hormones, is called positive feedback
• Abundance of one element inhibits the release of certain hormones, called negative feedback¹

Let's find out what are the functions of these important hormones.

The 5 main hormones

Insulin

Insulin is secreted by the pancreas. Its main function is to make glucose accessible to be absorbed by the cell. When the insulin secretion is disturbed, or when the cells develop insulin resistance, glucose can not be absorbed by the body, that in turn results in increased glucose levels resulting in diabetes. The mainfunctions are as follows:

• Helps in glucose absorption by the cells and converting them into glycogen.
• Inhibits gluconeogenesis(conversion of fats into energy)
• Increases fat synthesis in the liver.

In short, insulin helps to store food in the form of fat in the liver for future use.

When insulin fails to produce in the body, it is an autoimmune condition called type I Diabetes. In addition, when cells develop insulin resistance, it’s often known as type II Diabetes when the body no longer reacts to insulin.

Insulin supplementation is required for the former case, anti-diabetic drugs like metformin can be used in later case.²

Thyroxine

Thyroxine is released by the thyroid gland. Its secretion is increased as thyroid releasing hormone secreted by hypothalamus, which is released and stimulates anterior pituitary hormone to release thyroid stimulating hormone that causes the release of T3 AND T4, thyroid hormones from the thyroid gland. With an increase in levels of thyroid hormones, TSH & TRH are inhibited, causing a reduced release of T3 and T4, which is called a negative feedback mechanism.¹

Thyroxine hormone has a critical role in the body,

• Maintain metabolism of the body
• Regulation of temperatures in extreme climates 
• Production of energy with burning of carbohydrates, proteins and lipids
• helps in the development of neural structure, teeth, bone and hair follicles even in the fetal stage²

Disturbances in the secretion of thyroid hormones are termed as hypothyroidism and hyperthyroidism.

• Hypothyroidism, characterised by decreased metabolic rate resulting in weight gain, depression, psychosis and loss of cognitive abilities like memory loss, and sleep disturbances.

• Hyperthyroidism, characterised by increased metabolism, resulting in weight loss, anxiety, palpitations, tremors. It can be treated with antithyroid drugs like propylthiouracil and beta adrenergic drugs like atenolol, or with beta blockers

Cortisol 

Cortisol is released by adrenal glands, which are stimulated by the Adrenocorticotropic hormone(ACTH) by the anterior pituitary gland. Corticotropin-releasing hormone (CRH) from the hypothalamus, secreted by stress during various physiological or psychological conditions. CRH stimulates the pituitary to release ACTH. This entire procedure called HPA axis. The functions of Cortisol includes:

• Increase blood glucose level by gluconeogenesis, lipolysis and proteolysis.
• Increase blood pressure
• Increase appetite
• Decrease bone formation
• Decrease inflammation²

Steroid therapy is administered in various inflammatory and autoimmune conditions to reduce inflammation and suppress immune response.

Hypersecretion of this hormone results in Cushing's syndrome, characterised by muscle weakness, osteoporosis(brittle bones), and irregular deposition of fat. 

Undersecretion caused Addison's disease characterised by dehydration, loss of appetite, muscle weakness, diarrhoea, nausea and vomiting.¹

Estrogen

It is a female sex hormone, mainly secreted by ovaries. It can also be secreted by adipose tissue and skin. The main function of estrogen are

During puberty

• Develop female secondary sexual characteristicsbreasts,for example
• Control the pattern of fat distribution that contribute to a particular female body shape

During adulthood

• Maintenance of menstrual cycle
• Hormonal regulation during lactation and pregnancy²

Menopause is the state of absence of periods continuously for 12 months. It usually occurs after the age of 50 years. The most common symptoms at this stage are hot flashes, brittle bones(osteoporosis), anxiety, depression, and irritability. Hormonal supplementation can relieve the symptoms, but has also been proven to cause breast cancer and uterine cancer in some cases.¹

Testosterone 

Testosterone is released primarily by adrenal glands both in males and females and also from ovaries. Its main function is to help in the development of the male genital tract.¹ The other functions of testosterone are as follows:

In puberty:

• Ensures the growth of internal and external male genital parts

During puberty

• Development of male sex organs and other male secondary sexual characteristics like deepening of voice, growth of axial, pubic and facial hair

In adults

• Regulate sperm production
• Maintain masculinity, and libido

 Similar to estrogen, testosterone secretion depletes with age.²                             

Though estrogen or progesterone are sexual hormones, every male has minute secretion of estrogen and female with testosterone as they have their role in the reproduction system. The role of estrogen in males is to maintain libido, erectile functions and spermatogenesis.³ The role of testosterone in females is found to have an effect on cardiovascular and muscular health.⁴

Summary

Every hormone released helps in maintaining the daily functions of our body, gaining a deeper understanding in hormones functions can be helpful for early diagnosis and quick approach to avoid long lasting health issues.