Hormones – Definition, Types, Functions

Hormones: As a child is born, he or she experiences a rapid change in the body related to growth and development. A child grows to attain puberty, adulthood and gets older with time. A human being has several feelings, emotions, and changes in the body throughout his lifetime. Now have you ever thought about what regulates these changes? The answer is “Hormones”. Hormones are chemical substances that regulate the functions of various organs of the human body. They are secreted by endocrine glands that are a special group of cells that secrete hormones. The major endocrine glands are the pituitary, pineal, thyroid, thymus, adrenal glands, and pancreas. All these glands secrete a specific hormone that performs their specific function. 

What are Hormones?

Hormones are chemical messengers that are organic compounds produced in animal bodies to regulate various activities and behaviour. The term “Hormone” was derived in 1905 from the Greek word “hormon”, which means to move or set in motion”. They are signalling molecules that send signals to the cells to perform their respective activities. Hormones are secreted by Endocrine glands, also known as ductless glands, which means they are directly secreted into the bloodstream rather than ducts. The major endocrine gland in the body includes the pituitary gland, thymus, pineal gland, thyroid, pancreas, testes, and ovaries. Even a very small amount of hormones secreted by these glands can bring significant and visible change in the human body.

Functions of Hormones

Different hormones act on different tasks of body functions and processes as mentioned below:

1. Proper growth and development of the body.
2. Metabolism of food that we eat.
3. Reproductive growth and sexual health of an individual.
4. Alteration of mood.
5. Maintenance of body temperature, biological clock (sleep-wake cycle) and thirst in the body.

Types of Hormones

Based on the regulatory activities, hormones are divided into two types:

1. Amino acid derivatives (Proteins and peptide hormones)

Peptide hormones are derivatives of amino acids and are water-soluble. They do not enter into the target cell but bind to the receptors of the target cell and act as a secondary messenger. One of the important peptide hormones is insulin produced by the pancreas.

2. Steroids Hormones

Steroid hormones are lipid-soluble hormones that enter inside the nucleus of the cell and alter genetic functions. These hormones are involved in direct gene activation. Steroids are further divided into two classes:

1. Adrenal cortical hormones like androgens
2. Sex hormones like testosterone and estrogen

Endocrine Glands and the Hormones Secreted

The endocrine glands secrete hormones to control and coordinate your body’s internal metabolic activities, energy level, growth and development, reproduction, and response to injury, stress, and environmental factors. A list of some important hormones secreted by their respective endocrine glands are given below:

Adrenal Gland

The adrenal gland secretes hormones ‘Epinephrine‘ that increases heart rate, intake of oxygen and blood flow, and ‘Norepinephrine‘ that maintains blood pressure, another hormone corticosteroid, acts as an anti-inflammatory hormone, maintains blood sugar levels, blood pressure, and strength of muscles.

Pituitary Gland

This gland is also referred to as the ‘master gland’ as it controls many vital functions of the human body. List of some important hormones secreted by the pituitary gland are:

1. Antidiuretic Hormone (ADH) or vasopressin regulates water retention and controls blood pressure.
2. Adrenocorticotropic hormone (ACTH) controls the production of sex hormones (estrogen in females and testosterone in the male).
3. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) control the production of sex hormones and the production of eggs in women (ovulation) and sperm in men.
4. Oxytocin is also known as the birth hormone as it stimulates the contraction of the uterus and mammary ducts to produce milk.
5. Thyroid Stimulating Hormone (TSH) stimulates the production of thyroid hormone that controls metabolism and affects the growth, maturation, and nervous system activities.

Kidneys

The kidney is a vital organ that secretes hormones like Renin and angiotensin that directly controls blood pressure and regulate aldosterone production from the adrenal glands.

Hypothalamus 

1. Hypothalamus regulates the release of growth hormone-releasing hormone (GHRH) in the pituitary gland.
2. Gonadotropin-releasing hormone (GnRH) regulates the production of LH/FSH in the pituitary gland.

Thymus

The thymus is an endocrine gland that helps in the development of lymphoid organs.

Cell Signaling

The process by which cells communicate with other cells in the body is known as cell signalling. This signalling can be intercellular as well as intracellular. Based on the type of interaction, cell signalling is of the following types:

1. Autocrine Signaling – In this type of signalling, hormones produced by a cell bind the autocrine gland within the same cell itself. It means a cell targets itself in this process.
2. Paracrine Signaling – When a cell targets a neighbouring cell to bind the signalling molecules, then this type of cell signalling is known as paracrine signalling.
3. Endocrine Signaling – This is the most efficient type of cell signalling where the hormones reach the target cells through the bloodstream.

Summary

In a nutshell, we can infer that hormones are chemical substances produced in the body that controls and regulate the activity of certain target cells or organs. Hormones are complex organic compounds with very complex origins and functions. Lack or improper secretion of any hormone may lead to serious health issues and can cause genetic defects also. Many hormones are secreted by special glands such as endocrine glands, such as thyroid hormone is produced by the thyroid gland. The major endocrine glands are the pituitary, pineal, thyroid, thymus, adrenal glands, and pancreas. Hormones have immense importance on the human body as they regulate complete growth, development, behaviour, etc. Hormones are of two types: peptide hormones and steroid hormones. 

Peptide hormones are derivatives of amino acids and are water-soluble, while; steroid hormones are lipid-soluble hormones that enter inside the nucleus of the cell and alter genetic functions. Name of different hormones secreted in the body is hormones ‘Epinephrine’ that increases heart rate, intake of oxygen and blood flow as well as ‘Norepinephrine’ that maintains blood pressure, Vasopressin, ACTH, LH, FSH, Oxytocin, TSH, and many more hormones are secreted by the pituitary gland and perform vital body functions. 

Some growth hormones are secreted by the hypothalamus that maintains proper growth and development of the body. The pancreas secretes insulin that is very important to maintain the glucose level in the body. Thus, we can say that hormones are an integral part of our body.

FAQs on Hormones

Q.1. What are the five hormones?
Ans: (i) Antidiuretic Hormone (ADH) or vasopressin regulates water retention and controls blood pressure.
(ii) Adrenocorticotropic hormone (ACTH) controls the production of sex hormones (estrogen in females and testosterone in males).
(iii) Luteinizing hormone (LH) controls the production of sex hormones and the production of eggs in women (ovulation) and sperm in men.
(iv) Oxytocin is also known as the birth hormone as it stimulates the contraction of the uterus and mammary ducts to produce milk.
(v) Thyroid Stimulating Hormone (TSH) stimulates the production of thyroid hormone that controls metabolism and affects growth, maturation, and activities of the nervous system.

Q.2. Which are important hormones in the body?
Ans: Some of the important hormones in the body are growth hormones (GH) that regulate proper growth and development in the body. Thyroid Stimulating Hormone (TSH) stimulates the production of thyroid hormone that controls metabolism and affects growth, maturation, and different activities of the nervous system.

Q.3. What are the eight hormones?
Ans: The lists of eight hormones are thyroid-stimulating hormone, oxytocin, prolactin, estrogen, testosterone, progesterone, insulin and cortisol.

Q.4. What are hormones, and what is their purpose?
Ans: Hormones are chemical messengers that are organic compounds produced in the body by endocrine glands. They are chemical compounds that send signals to the cells to perform their respective activities. Hormones are secreted by endocrine glands, also known as ductless glands, which means they are directly secreted into the bloodstream rather than ducts. The major endocrine gland in the body includes the pituitary gland, thymus, pineal gland, thyroid, pancreas, testes, and ovaries. Even a very small amount of hormones secreted by these glands can bring significant and visible change in the human body

Q.5. Where does the production of female estrogen hormone occur?
Ans: The female hormone estrogen is produced by the ovaries, which produces a woman’s eggs. It is the main source of estrogen in the body. Estrogen is a category of sex hormone responsible for the regulation development of the female reproductive system and secondary sex characteristics.

Q.6. How do the hormones in your body affect your health?
Ans: Hormones are very important for our health as they maintain the proper growth and development of our bodies. Many hormones perform specific functions like Antidiuretic Hormone (ADH) or vasopressin, which regulates water retention and controls blood pressure. Adrenocorticotropic hormone (ACTH) controls the production of sex hormones (estrogen in females and testosterone in males) in the body. Luteinizing hormone (LH) controls the production of sex hormones and the production of eggs in women (ovulation) and sperm in men.
Stimulating Hormone (TSH) stimulates the production and secretion of thyroid hormone that controls metabolism and affects growth, maturation, and activities of the nervous system in the body. Oxytocin is also known as the birth hormone as it stimulates the contraction of the uterus and mammary ducts to induce lactation.

 Study About Hormones In Humans Here

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