The word hormone comes from the Greek word hormon, which literally translates as “to bring into action.” Hormones have a role in practically every physiological activity that occurs in our bodies.

Generally speaking, a hormone may be described as a specific product (organic substance) of an endocrine gland that is produced into the bloodstream and then transported to a specific portion of the body where it has a specific physiological impact on the body. This impact can have either an excitatory or an inhibitory effect on the body.

Endocrine glands do not have any ducts, thus the hormones they produce are released straight into the circulation. As a result, the endocrine glands are often referred to as “ductless glands” when they do not produce any secretions. The holocrine glands are endocrine glands that solely release hormones, and they are found in the reproductive system (e.g., thyroid, parathyroid, adrenals, and pituitary glands). Heterocrine glands are glands that perform two or more tasks at the same time (secretion of hormones and performance of other activities) (e.g., pancreas, testes ovaries, etc.).

Properties of Hormones 

1. The hormones are created by specific glands and released directly into the bloodstream.
2. The hormones are delivered by the bloodstream from the endocrine cells to the target cells or organs where they operate as a ‘chemical message’ by controlling the rates of certain metabolic events.
3. The hormones have their impact on different tissues of the body rather than the tissues where they are created in a certain area.
4. Hormones are required in very minute amounts, and their action on the responding tissue can be either excitatory or inhibitory, depending on the quantity of hormones present and the physiological condition of the responding tissue.
5. Hormones have diverse molecular structures that distinguish them from one another. Steroids, proteins, peptides, and amino acid derivatives are all examples of anabolic steroids.

Chemical Nature of Hormones

Hormones serve as the second line of communication and control in the body, after the nervous system. They are produced by endocrine glands such as the pituitary gland, the thyroid gland, and others. They are sluggish to react when it comes to controlling organs and coordinating actions amongst them. They are chemical in nature, and as a result, they communicate through a chemical network. They can be classified into the following categories based on their chemical composition:

1. Steroid hormones
2. Amine hormones
3. Peptide hormones
4. Protein hormones
5. Glycoprotein hormones
6. Eicosanoids hormones

1. Steroid hormones: These are composed of lipids, which are mostly generated from cholesterol, and are produced by the adrenal glands. Testosterone, oestrogen, and progesterone are examples of such hormones.

2. Amine hormones: These hormones are derived from the amino acid tyrosine and are composed of amines, which are derivatives of that amino acid. T3, T4, Epinephrine, and Norepinephrine are examples of endogenous hormones.

3. Peptide hormones: These hormones are made up of only a few amino acid residues and are found in a linear chain form, similar to insulin. For example, oxytocin and vasopressin are hormones that are composed of merely nine amino acids.

4. Protein hormones: These hormones are composed of protein containing several amino acids and are classified as primary, secondary, and tertiary in structure. Insulin is an example of an exogenous hormone. Glucagon,STH.

5. Glycoprotein hormones: The glycoprotein hormones found in nature are carbohydrate- and protein-conjugated proteins, which means that they are made up of both carbohydrate and protein. Mannose, galactose, and fucose are the carbohydrate groups present. LH, TSH, and FSH levels were measured.

6 .Eicosanoids hormones: Eicosanoids are tiny fatty acid derivatives derived from a range of arachidonic acids that function as hormones. Prostaglandins are a kind of protein.

Conclusion

In terms of chemical classification, hormones are divided into two groups: lipid-soluble hormones and water-soluble hormones. This difference is made based on the chemical makeup of hormones, which determines their chemical activity. It is important to remember that the plasma membrane is a selectively permeable phospholipid bilayer that rejects the majority of water-soluble molecules while permitting the passage of most lipid-soluble molecules. As a result, the chemical constitution of a hormone determines the entire foundation of the hormone’s metabolism, including its transport through the bloodstream, interaction with its target, and elimination from the body (or elimination).

Hormones can be subdivided into groups depending on the chemical structures of their hormones within each of the two chemical categories. Among the hormones produced by the body are steroid hormones, thyroid hormones produced by the body from the amino acid tyrosine, and other hormones that are amino acid derivatives, peptides, or proteins.