How antidepressants work. PART 1

Today I searched for some clear explanation on how SSRI antidepressants work, that will not resemble an encyclopedic article with dozens of medical terms on top of each other.

And I’ve found it. Call it love from the first sight if you wish but the article I am quoting below is amazingly clear and simple for understanding. I am dividing it into 3 parts + several separate posts about each type of antidepressants. First part explains how our brain works. Second part gives a basic review on neuron transmitters. Third part – and depression develops.
If you have a clear picture on these subjects you may then skip these parts and move to medications descriptions.

PART 1

1. The brain

“In order to try to understand a little about how drugs work, it is best to first learn a few facts about the brain. Each human being has: One head. One brain. Each brain has somewhere around 10,000,000,000 brain cells. Each brain cell has lots of connections with other brain cells by means of nerve fibres (the wiring connecting brain cells together). There are about 4 million miles of nerve fibres in each brain. Some fibres may have up to 10,000 branches in them. Each brain cell has lots of connections with other cells, possibly over 25,000! The junctions at the end of the neurones are called synapses.

2. A Synapse

Synapses are very important because:
They are the route by which brain cells talk to each other
Synapses are of the same basic design in the brain, the heart, the legs etc.
There are a lot of them If we can get chemicals (e.g. drugs) into the gap between them in the brain, we can affect the way in which brain cells talk to each other e.g. we can slow the messages down, speed the up etc.

A synapse looks like this:

In the drawing you will see the following:

- Axon - A neurone (or cell body) has many axons (or nerve fibres).
- Vesicles - these contain the transmitter.
- Transmitters - these are small chemicals used by brain cells as messengers. They are stored in the vesicles in the nerve ending ready to be released
- Receptors - these are structures on the surface of the receiving cell which have a space designed just for the transmitter (if the transmitter is a key, receptors are the lock into which they fit)
- Enzymes - these surround the synapse and break down any spare transmitter that might leak out to other synapses nearby. - Electrical signal - This is the way in which one brain cell sends a message to another. The signal travels down the nerve fibre rather like an electrical "Mexican Wave".”

Sounds pretty simple, huh? Let’s move to PART 2