Neurotransmitters
What is The Neurotransmitter?
The brain controls every part of the body, down to the smallest of the actions. This is possible due to the vast network of nerves spread across the body. These are specialized cells that carry biochemical messages to specific regions of the body. These messages are carried via neurotransmitters.
Also known as chemical messengers, neurotransmitters carry “messages,” which result in a response. Chemically, neurotransmitters can be amino acids, monoamines, or peptides. These are synthesized in the neurons. In fact, one of the criteria for classifying a chemical as a neurotransmitter is that it is produced in a neuron. These chemical messengers are responsible for various functions
What are The Responsibilities of Neurotransmitters?
Unlike what you might have imagined, the neurotransmitter network is not segregated into specific messengers allotted for specific functions. It is an interconnected web of all the neurotransmitters responsible for multiple functions.
For instance, all the neurotransmitter systems discussed later can control wakefulness. The adrenaline system can control completely unrelated functions like energy homeostasis (the control of food intake and caloric expenditure ), respiration and stress.
We have talked about neurotransmitter “systems” in this section. These systems are based on their respective pathways. Pathways are basically a cascade of chemical reactions that will result in one or more products. Hence, a nerotransmitter system will follow its respective pathways.
Based on this pattern, there are six neurotransmitter systems:
- Dopamine system
- Noradrenaline or norepinephrine system
- Serotonin system
- Acetylcholine system
- Histamine system
- Adrenaline system
These systems of neurotransmitters are responsible for the following functions:
- Sleep cycle
- Emotions and feelings
- Sexual functions
- Response to external stimulus
- Stress response
- Hormone regulation
- Muscle movement
- Sense of hunger, thirst, etc.
- Control of various body systems like respiratory, gastrointestinal, etc.
- Senses
Apart from these, the neurotransmitters can control lots of functions that cannot be mentioned in a single list.
How do Neurotransmitters Work?
Generally, the nerve cells release certain neurotransmitters as a response. Anything the neuron senses, like high temperature, hormones, or neurotransmitters from outside the cell, may trigger a response.
The nerve cell releases these neurotransmitters from one end, which is the “tail” of the neuron, from a region called the synaptic vesicle. They then travel through the synapse, which is the small space between two nerve cells. These neurotransmitters are then taken up into the synaptic cleft, which is an area of neurotransmitter signalling. These clefts can either be present on the “head” of the nerve cell or the surface of a gland or muscle. This is how a nervous message travels from one cell to another.
After a certain time, these neurotransmitters are cleared from the synapses. This occurs via the process of neuronal uptake or being absorbed in their target cells. This is important for two reasons:
- To clear the way for the next nerve response.
- To prevent the same response from persisting infinitely. For example, after accidentally getting burned, you wouldn’t want the sensation to be prolonged indefinitely.
All this process occurs in a fraction of a second. This is why you can immediately sense if you are pricked and the brain immediately responds to anything wrong in the body.