Hormones function as chemical messengers that help different parts of the body communicate and work together.
They are made by endocrine glands and travel through the bloodstream to reach target organs or tissues.
Here’s how hormones act as messengers, explained:
1. Hormone production
A specific endocrine gland (like the pituitary, thyroid, or pancreas) makes a hormone in response to a signal — for example, stress, hunger, or low blood sugar.
2. Release into the bloodstream
The hormone is released into the blood, which carries it all over the body.
3. Target cell detection
Only certain cells, called target cells, can respond to that hormone because they have specific receptors that match it — like a lock and key.
4. Binding to the receptor
The hormone binds to its receptor on or inside the target cell.
This starts a series of reactions inside the cell, known as a signal transduction pathway.
5. Cellular response
The cell then performs the required action, such as:
- Making or stopping a protein
- Releasing another hormone
- Changing metabolism
- Growing or dividing
In short:
Hormones act as chemical messengers by carrying information from glands to target cells, telling them what to do.
This helps the body maintain balance, control growth, metabolism, and many other vital functions.