Difference Between Hormones and Pheromones

Main Difference – Hormones vs Pheromones

Hormones and pheromones are chemical signaling molecules produced by animals. Most hormones and pheromones are made up of proteins. Both hormones and pheromones are produced inside the body. The main difference between hormones and pheromones is that hormones act inside the body, changing the functions and behavior of the animal whereas pheromones act on another animal of the same species by changing the behavior. Abscisic acid, auxins, cytokinins, pituitary hormones, and male and female sex hormones are some examples of hormones. Sex pheromones, trail pheromones, signal pheromones, releaser pheromones, alarm pheromones, and aggregation pheromones are some examples of pheromones.

Key Areas Covered

1. What are Hormones
      – Definition, Types, Action
2. What are Pheromones
      – Definition, Types, Action
3. What are the Similarities Between Hormones and Pheromones
      – Outline of Common Features
4. What is the Difference Between Hormones and Pheromones
      – Comparison of Key Differences

Key Terms: Abscisic Acid, Amino Acid Derivatives, Cytokinins, Hormones, Peptide Hormones, Sex Pheromones, Steroid Hormones, Tail Pheromones

What are Hormones

Hormones are chemical messengers secreted inside the body of plants and animals. The glands that produce and secrete hormones are called endocrine glands. Hormones are secreted directly into the blood in order to be transported to their target tissues. The three categories of hormones are steroids, proteins/peptides, and amino acid derivatives. Male and female sex hormones such as testosterone, estrogen, and progesterone are steroid hormones. The insect molting hormone cortisone is also a steroid hormone. Most hormones are peptide hormones such as pituitary hormones, insulin, and secretin. Some hormones such as adrenaline and thyroxine are amino acid derivatives. The types of hormones are shown in figure 1.

Figure 1: Types of Hormones

Very low concentrations of hormones can produce their effect in the body. Steroid hormones bind to the receptors in the cytoplasm while peptide or protein hormones bind to the receptors on the cell membrane. Protein/peptide hormones exert their effect by means of second messengers. The concentration of a particular hormone in the bloodstream is determined by the hormones secreted by the pituitary gland. Too much or too little hormones can cause diseases in the body.

Plant hormones determine the formation of leaves, stems, flowers, fruits, and shedding of leaves. Abscisic acid, auxins, cytokinins, ethylene, and gibberellins are examples of plant hormones.

What are Pheromones

Pheromones are chemicals produced by animals and insects that change the behavior of another animal or insect of the same species. Though pheromones are produced inside the body, they are secreted to the outside. Most pheromones induce the sexual behavior of the opposite sex. Typically, all insects use pheromones to communicate with each other. Several types of pheromones can be identified. Aggregation pheromones are used to select a mate and defend against predators. These pheromones bring a group of individuals together. The groups are called aggregations. An aggregation of bug nymphs is shown in figure 2.

Figure 2: Aggregation

Some insects use alarm pheromones to alert others about a threat. Releaser pheromones change the behavior of the recipient. Signal pheromones exert short-term responses. Cats and dogs use territorial pheromones to mark their boundaries. Sex pheromones indicate the availability of female for mating. 

Similarities Between Hormones and Pheromones

• Both hormones and pheromones are signaling molecules produced by animals.
• Both hormones and pheromones are made up of proteins in most of the cases.
• Both hormones and pheromones are produced inside the body.
• Both hormones and pheromones change the functioning and behavior of animals.

Difference Between Hormones and Pheromones

Definition

Hormones: Hormones refer to the regulatory substances which are transported in blood or sap, stimulating specific cells to perform their functions.

Pheromones: Pheromones refer to the chemical substances which are released into the environment by animals and insects, affecting the behavior of the others in the same species. 

Action

Hormones: Hormones act inside the body of the animal or plant that secretes it.

Pheromones: Pheromones act outside the body of animal or insect that secretes it.

Function

Hormones: Hormones have wide-range of functions in the body.

Pheromones: Pheromones have few functions of the body.

Importance

Hormones: Hormones coordinate the functions of the body along with the nervous system.

Pheromones: Pheromones act as messengers to attract males towards the females, aiding sexual reproduction.

Examples

Hormones: Abscisic acid, auxins, cytokinins, pituitary hormones, and male and female sex hormones are the examples of hormones.

Pheromones: Sex pheromones, trail pheromones, signal pheromones, releaser pheromones, alarm pheromones, and aggregation pheromones are examples of pheromones.

Conclusion

Hormones and pheromones are two types of chemical signaling molecules. Hormones stimulate or inhibit the functions of the body. But, pheromones act on organisms other than their producer. Hormones are produced by animals and plants. Pheromones are produced by animals and insects. The main difference between hormones and pheromones is their point of action.

Reference:

1.“Hormones and Pheromones.” Biology 11 Fall 2005 Hormones and Pheromones, Available here.
2.Nordqvist, Christian. “What Are Pheromones? Do Humans Have Pheromones?” Medical News Today, MediLexicon International, 14 Apr. 2016, Available here.

Image Courtesy:

1. “1802 Examples of Amine Peptide Protein and Steroid Hormone Structure” By OpenStax College – Anatomy & Physiology, Connexions Web site. Available here, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia
2. “Bug aggregation” By L. Shyamal – Own work (CC BY 2.5) via Commons Wikimedia