1. Hormones

Hormones: These are chemical substances produced in small amounts by some specialized organs called ductless or endocrine glands. The hormones produced by the glands move to different parts of the body through the bloodstream. T. Addison was the father of endocrinology. These are important in regulating metabolic processes and sex characteristics. These are called chemical messengers. Chemically these are classified into 3 types, namely steroids, polypeptides, and amines.

Attribution: Concepts of Biology - 1st Canadian Edition by Charles Molnar and Jane Gair is licensed under a Creative Commons Attribution 4.0 International License
URL: https://opentextbc.ca/biology/chapter/18-5-endocrine-glands/

Proteins are responsible for hormone synthesis. Hormones are the chemical messages produced by the endocrine glands. When an endocrine gland is stimulated, it releases a hormone. The hormone is then transported in the blood to its target cell, where it communicates a message to initiate a specific reaction or cellular process. For instance, after you eat a meal, your blood glucose levels rise. In response to the increased blood glucose, the pancreas releases the hormone insulin. Insulin tells the cells of the body that glucose is available and to take it up from the blood and store it or use it for making energy or building macromolecules. A major function of hormones is to turn enzymes on and off, so some proteins can even regulate the actions of other proteins.