Brain Chemicals

Human body cannot function without chemical messengers called neurotransmitters. They are responsible for transporting chemical "messages" from one neuron (nerve cell) to the subsequent target cell. The following target cell may be a gland, muscle, or another nerve cell.

The nervous system in the body is a huge network of nerve cells that communicate electrical impulses between nerve cells and the cells they are intended to target. Nervous system regulates the operation of the organs as well as everything from the intellect to the muscles. In other words, nerves play a role in everything think, feel, and do. Human nerve cells transmit and receive data from every part of human body. Body must constantly get feedback to operate at its best.

What Body Functions do Nerves and Neurotransmitters Help Control?

Nervous system oversees several bodily processes, including:

• Blood pressure and heartbeat
• Breathing
• Muscular actions
• Feelings, memories, learning, and thoughts
• Ageing, recuperation, and sleep
• Response to stress
• Hormone control
• Digestion, a hungry or thirst pang
• Responses to what a person see, hear, feel, touch, and taste are called senses.

How do Neurotransmitters Work?

In human body, there are many billions of nerve cells. Typically, there are three components to a nerve cell:

• A cell body- The production of neurotransmitters and sustaining the nerve cell's functionality depend on the cell body.
• An axon- Along the nerve cell, the axon transports electrical signals to the axon terminal.
• An axon terminal- Neurotransmitters are used at this point to convert the electrical message into a chemical signal to interact with the subsequent group of nerve cells, muscle cells, or organs.

The axon terminal is a region of the neuron that contains neurotransmitters. They are kept inside synaptic vesicles, which have thin walls. Numerous thousands of neurotransmitter molecules can fit inside each vesicle. The electrical charge of a message or signal induces the neurotransmitter vesicles to fuse with the nerve cell membrane at the very edge of the cell as it moves along a nerve cell. The neurotransmitters are subsequently discharged from the axon terminal into the space between one nerve cell and the next target cell (another nerve cell, muscle cell, or gland), where they now deliver the message.

Neurotransmitters transport the message through this region, known as the synaptic junction, which is less than 40 nanometres (nm) broad (for comparison, the width of a human hair is approximately 75,000 nm). Each type of neurotransmitter gives to a distinct receptor on the target cell, acting similarly to a key that can only fit and operate in the lock that it was designed to fit. After attaching, the neurotransmitter causes the target cell to undergo a change or act, such as sending an electrical signal to another nerve cell, contracting a muscle, or releasing hormones from a glandular cell.

What Behaviour or Alteration do Neurotransmitters Convey to the Target Cell?

Depending on the specific neurotransmitter, neurotransmitters can communicate one of three distinct actions in their messages.

• Excitatory- Excitation-inducing neurotransmitters "excite" the neuron, which then "fires off the message," continuing the transmission of the signal to the subsequent cell. Neurotransmitters like glutamate, adrenaline, and norepinephrine are examples of excitatory neurotransmitters.
• Inhibitory- Neurotransmitters that act as inhibitors stop the chemical message from being transmitted further. Inhibitory neurotransmitters include glycine, serotonin, and gamma-aminobutyric acid (GABA).
• Modulatory- Neurotransmitters that act as inhibitors stop the chemical message from being transmitted further. Inhibitory neurotransmitters include glycine, serotonin, and Gamma-Aminobutyric Acid (GABA).

What Transpires after Neurotransmitters Relay their Message?

Neurotransmitters must remove their molecules from the synaptic cleft (the area between the nerve cell and the next target cell) after transmitting their message.

There are three ways they accomplish this:

• Fade away (the diffusion process).
• Are taken up and utilised once more by the nerve cell that produced them (a process known as reuptake).
• Are degraded (a process known as degradation) by enzymes within the synapse so that it cannot be recognised or attach to the receptor cell.

How many Different Types of Neurotransmitters are There?

There are at least 100 neurotransmitters that are known to science, and many more may still be undiscovered. Based on their chemical makeup, they can be categorised into kinds. The following are some of the more well-known types, neurotransmitter examples, and their functions:

Amino acids neurotransmitters

Most of human nervous system's functions include these neurotransmitters.

• Glutamate- It is the neurotransmitter that is most prevalent in human brain. It is crucial for cognitive processes like reasoning, learning, and memory. Seizures, dementia, Parkinson's disease, and Alzheimer's disease are all correlated with abnormal glutamate levels.
• Gamma-Aminobutyric acid (GABA)- The most prevalent inhibitory neurotransmitter in human nervous system, especially in the brain, is GABA. It controls brain activity to guard against issues with tension, irritation, focus, sleep, seizures, and depression.
• Glycine- The most prevalent inhibitory neurotransmitter in human spinal cord is glycine. Glycine regulates metabolism, pain transmission, and auditory processing.

Monoamines neurotransmitters

These neurotransmitters have a wide range of functions in human nervous system, particularly in the brain. Neurotransmitters called monoamines control consciousness, cognition, attention, and emotion. A lot of neurological conditions involve anomalies in monoamine neurotransmitters, and a lot of regularly used medications have an impact on these neurotransmitters.

• Serotonin- An inhibitory neurotransmitter is serotonin. Serotonin plays a role in the regulation of pain, anxiety, appetite, sexuality, and mood. Seasonal affective disorder, anxiety, sadness, fibromyalgia, and chronic pain are diseases linked to serotonin imbalance. Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are medications that control serotonin and treat various illnesses.
• Histamine- Histamine controls a variety of bodily processes, including motivation, eating habits, and alertness. Asthma, bronchospasm, mucosal edoema, and multiple sclerosis are all caused by histamine.
• Dopamine- Human body's reward system involves dopamine and is responsible for feelings of pleasure, heightened arousal, and learning. Additionally, dopamine aids in motivation, focus, memory, sleep, and mood. Parkinson's disease, schizophrenia, bipolar disorder, restless legs syndrome, and attention deficit hyperactivity disorder (ADHD) are diseases linked to dopamine system dysfunctions. Cocaine, methamphetamine, and amphetamines are just a few of the extremely addictive substances that affect the dopamine system.
• Epinephrine- Human body's alleged "fight-or-flight response" to stress and anxiety is a combination of two hormones termed norepinephrine (see below) and epinephrine (commonly known as adrenaline). To act or respond to various stimuli, these neurotransmitters heighten attention and focus while accelerating heart rate, respiration, blood pressure, blood sugar, and blood flow to human muscles. High blood pressure, diabetes, heart disease, and other health issues can result from taking too much epinephrine. Epinephrine is a medication used to treat cardiac arrest, anaphylaxis, asthma attacks, and serious infections.
• Norepinephrine-Noradrenaline, commonly known as norepinephrine, raises heart rate and blood pressure. Its effects on alertness, arousal, decision-making, attention, and focus are what are most well-known about it. Numerous drugs (stimulants and antidepressants) work by increasing norepinephrine levels to improve attention and concentration in order to treat ADHD or by modulating norepinephrine in order to alleviate the symptoms of depression.

Peptide neurotransmitters

Peptides are polymers or chains of amino acids.

• Endorphins- Human body naturally produces endorphins to ease pain. They influence how we experience pain. Endorphin release results in "feel good" emotions as well as a reduction in discomfort. Some types of headaches and fibromyalgia may be caused by low endorphin levels.

Acetylcholine

This excitatory neurotransmitter performs a variety of tasks in both the peripheral nervous system (nerves that branch from the CNS) and central nervous system (CNS [brain and spinal cord]). Most of the neurons in human autonomic nervous system, which controls the heart rate, blood pressure, and gastrointestinal motility, emit acetylcholine. Muscle contractions, memory, motivation, sexual desire, sleep, and learning are all influenced by acetylcholine. Acetylcholine levels that are out of balance have been related to health problems like Alzheimer's disease, seizures, and muscle spasms.

What Causes a Neurotransmitter to Malfunction?

Neurotransmitters may not function properly due to a variety of factors. Generally speaking, a few of these issues are:-

1. One or more neurotransmitters are generated or released in excess or insufficiently.
2. The receiver cell's (the neuron, muscle, or gland) receptor isn't functioning properly. The neurotransmitter, which otherwise functions normally, is unable to efficiently notify the subsequent cell.
3. Because of inflammation and synaptic cleft injury, the cell receptors aren't absorbing enough neurotransmitter (see myasthenia gravis).
4. Too quickly reabsorbed neurotransmitters.
5. Fewer neurotransmitters can reach their target cells because of enzymes.

Neurotransmitters can be impacted by issues with other nerve components, pre-existing conditions, or drugs patients may be taking. Disease can also occur when neurotransmitters don't work properly. For instance:

1. A lack of acetylcholine can contribute to the memory loss associated with Alzheimer's disease.
2. Autism spectrum disorders may be linked to excessive serotonin levels.
3. Sudden, high-frequency firing of local neurons in human brain can arise from an increase in glutamate activity or a decrease in GABA activity, which can lead to seizures.
4. Mania is characterised by excessive norepinephrine and dopamine production as well as aberrant glutamate transmission.

How do medications affect the action of neurotransmitters?

The usefulness and function of neurotransmitters in the brain and spinal cord were recognised by scientists, as well as the significance of creating drugs that could affect these chemical messengers to treat a variety of medical ailments. Numerous drugs, especially those used to treat brain disorders, influence neurotransmitters in a variety of ways.

A neurotransmitter can reach nerve receptors more readily if an enzyme that breaks it down is inhibited by medication.

Example: The enzyme acetylcholinesterase, which degrades the neurotransmitter acetylcholine, is blocked by donepezil, galantamine, and rivastigmine. These drugs are used to treat Alzheimer's disease and other neurodegenerative conditions to stabilise and enhance memory and cognitive function.

Drugs may prevent the neurotransmitter from binding to its receptor location.

Example: A class of medications known as selective serotonin reuptake inhibitors prevents serotonin from entering and being absorbed by a nerve cell. These medications may be useful in the treatment of anxiety, depression, and other mental health issues.

Drugs may prevent a neurotransmitter's release from a nerve cell.

Example: Lithium is used to treat bipolar disorder and works in part by inhibiting the production of norepinephrine to reduce manic.

A Note from Doctor

Nearly every body-process involves neurotransmitters. Neurotransmitters are, more particularly, the chemical messengers that transport a nerve's message from one nerve cell to the following one. The human body cannot function without neurotransmitters. Specific health issues are caused by neurotransmitters that are present at either an excessively high or excessively low quantity. The amount of or the effect of neurotransmitters are changed by medications.