How antidepressants work. PART 2

Here goes the second part of the material. This one is about neurotransmitters's and receptors' work.

"3. What happens when a message is passed from one cell to another.

1. A brain cell decides to send a message to another cell in order to make something happen e.g. tighten a muscle, release a hormone, think about something, pass on a message etc.

2. An electrical impulse is sent from the brain cell down one of the nerve fibres/neurones towards the end. It travels at about 120 miles per hour.

3. This message or impulse arrives at the end of the nerve fibre. When it arrives, a chemical ("transmitter") is released from the nerve end.

4. The transmitter is then released and travels across the gap between the first nerve fibre and the next/receiving one.

5. The transmitter hits a receptor on the other side. It fits into it just like a key fitting into a lock.

6. When the transmitter hits the receptor, the receptor changes shape. This causes changes inside the nerve ending which sets off an electrical message in that nerve fibre on to the next brain/nerve cell. This sequence then carries on until the effect occurs e.g. the muscle moves etc.

7. The transmitter is either broken down by enzymes (10%) and removed or taken back up again into the nerve ending (i.e. recycled) - a process known as re-uptake.

8. The nerve fibre and synapse is then ready for next message

Important points:- The passage of messages only works one way or one direction- There is only one type of transmitter per synapse- The transmitter allows an electrical message to be turned into a chemical message and back into an electrical message.

4. "Transmitters"

Although there are over 80 known different "transmitters" in the brain, each nerve ending only has one type. These "neurotransmitters" tend to be grouped together and each seems to have specific roles e.g.:

Serotonin or 5-HT - In the brain, it controls mood, emotions, sleep/wake, feeding, temperature regulation, etc.Too much serotonin and you feel sick, less hungry, get headaches or migraines.Too little and you feel depressed, drowsy etc.

Dopamine - there are three main groups (or pathways) of dopamine neurones in the brain.In the brain, one group controls muscle tension and another controls e.g. emotions, perceptions, sorting out what is real/important/imaginary etc.Not enough dopamine in the first group and your muscles tighten up (e.g. as in Parkinson's Disease).Too much dopamine in the second group gives you an overactive brain i.e. too much "perception e.g. you may see, hear or imagine things that are not real

Noradrenaline (NA) - (sometimes called "norepinephrine" or NE)In the brain, it controls sleep, wakefulness, arousal, mood, emotion and drive.Too much noradrenaline and you may feel anxious, jittery etc.Too little and you may feel depressed, sedated, dizzy, have low blood pressure etc.

Acetylcholine (ACh) - In the brain, it controls arousal, the ability to use memory, learning tasks etc.Too much in your body and your muscles tighten up.Too little can produce dry mouth, blurred vision and constipation, as well as becoming confused, drowsy, slow at learning etc.

Glutamate - Acts as an "accelerator" in the brainToo much and you become anxious, excited and some parts of your brain may become overactive.Too little and you may become drowsy or sedated

GABA - Acts as a "brake" in the brainToo much and you become drowsy or sedated.Too little and you may become anxious and excited

In many mental health problems, it is known that some of these transmitters get out of balance e.g. you have too much or too little of a particular transmitter."

Seems like now you should understand the basic processes in your brain. Now let's head to PART 3 and see how depression develops.