What are hormones?
Q: What are hormones?
A: Hormones are the chemical messengers of the endocrine system. They are signals which adjust the body's internal workings, together with the nervous system. Every multicellular organism has hormones.
Q: How do hormones work?
A: When a hormone attaches to a receptor protein on a cell, it starts a mechanism for signalling. The cell or tissue that receives this message is called the 'target'. Hormones only act on cells which have the right receptors.
Q: What is an endocrine gland?
A: An endocrine gland is a group of cells that make something and release it (put it outside the cell). Many glands make hormones and most internal secretions are from endocrine glands.
Q: What is an exocrine gland?
A: An exocrine gland is one that secretes through a duct or tube, rather than directly into the bloodstream like an endocrine gland does. Examples of exocrine glands include sweat glands and salivary glands whose products are released outside the body.
Q: Who discovered hormones first?
A: The first discovery of a hormone was made in 1902 by scientist who identified secretin as being a hormone. The word 'hormone' was first used in 1905.
Q: Are all cells able to send messages?
A: Yes, many different kinds of cells can send messages via hormones attaching to their receptor proteins and starting mechanisms for signalling other cells or tissues in order to adjust bodily functions internally.
