Let's learn about the amazing system that works unconsciously in our body: the Autonomic Nervous System!

Have you ever wondered how you breathe, your heart beats, and the way you digest the food you eat all happen automatically, without you having to think about it? Isn't it amazing? Today we are going to talk about a very important system that performs many crucial functions inside our bodies, without us even realizing it. That is the autonomic nervous system, or in English, the ``Autonomic Nervous System''.

What is this so-called Autonomic Nervous System?

Simply put, the autonomic nervous system is a part of our entire nervous system. It's like a small but very important sub-network in a large computer network inside our body. Its main function is to control the involuntary bodily functions that are essential for our survival, but that we don't consciously control. This system works both when you're asleep and when you're awake. You don't even have to think about it, your brain takes care of it all.

Where is this located in our nervous system?

You know that our entire nervous system is divided into two main parts.

1. Central Nervous System : This is where our brain and spinal cord belong. Is it surprising? Even the retina and optic nerve in our eyes are structurally considered parts of the brain.

2. Peripheral Nervous System : This includes all other parts of our nervous system except the brain and spinal cord.

Now this peripheral nervous system is further divided into two parts:

• Somatic Nervous System : This is the part of the nervous system that controls the muscles we consciously control (like moving our arms) and the information we receive from our senses (hearing, smell, taste, touch ). Vision is not part of this system, as the parts of the eye that are responsible for vision are located in the brain.
• Autonomic Nervous System : This is our protagonist. This is the network of nerves that connects our brain to many of the internal organs inside our body.

What happens to the Autonomic Nervous System?

This autonomic nervous system is further divided into three main divisions, each of which performs separate functions.

Sympathetic Nervous System – the “fight-or-flight” mechanism

This system is what prepares our body in times of emergency, stress, or danger . Imagine that you are walking down the street and suddenly a dog attacks you. Your heart rate increases, your body sweats, your eyes widen, and your body prepares to run or fight, right? That's when the sympathetic nervous system kicks in. That's what we call the "fight-or-flight" response.

Parasympathetic Nervous System – “rest-and-digest” mechanism

This is the exact opposite of what the sympathetic nervous system does. It's what calms our bodies, relaxes them, and helps with digestion . When you've had a good meal and are sitting in a chair in the living room, you feel good... that's when this system is working.

Enteric Nervous System – Digestive specialist

This one is a bit special. This system mainly controls the functioning of our digestive system . Some scientists even say that it is as complex as a separate system.

How does the Autonomic Nervous System help other organs?

Just as a house needs electrical wiring to turn on the lights and make other appliances work, our brain also needs this network of nerves called the autonomic nervous system. These nerves provide the brain with the physical connections it needs to control many of the major internal organs in our body.

Let's see what this system controls in our body:

• Eyes : Although not directly related to your vision, it controls the size of your pupil (which controls how much light enters the eye) and the muscles that focus the eye.
• Tear, mucus, and salivary glands : This system controls the flow of tears from the eyes, the flow of mucus from the nose, and the flow of saliva from the mouth.
• Skin : It controls the production of sweat, as well as the muscles that make the body erect (that's what "hair grows").
• Heart and circulatory system : Controls how fast the heart beats, how hard it pumps, and the width of the blood vessels . This controls heart rate and blood pressure .
• Immune system : Your parasympathetic nervous system can activate immune system responses. This can happen during things like infections, asthma flare-ups, and allergies.
• Lungs : This controls the width of your airways and the network of passages that carry air in and out of your lungs.
• Small intestine and large intestine : It manages the entire digestive process from the small intestine to the large intestine. It also keeps the muscles in the rectum contracted until you need to defecate.
• Liver and pancreas : This regulates the release of hormones like ``Insulin`` from the pancreas, which converts the energy stored in the liver into ``Glucose`` that our cells can use.
• Urinary system : Controls the muscles in your bladder. This system is what keeps your bladder contracted until you need to urinate.
• Reproductive system : This system is very important for sexual functions such as sexual arousal (penis erection, secretion of lubricating fluids during sexual intercourse) and the ability to achieve orgasm.

Let's learn some more interesting facts about this autonomic nervous system.

• Balance between the sympathetic and parasympathetic systems : Think of it like a scale. While the sympathetic speeds up bodily functions, the parasympathetic slows them down or even reduces them. This balance is crucial for our well-being and survival .
• Different Communication Methods : Our nervous system uses chemicals (called ``neurotransmitters'') produced by various glands in our body and brain to communicate messages. It also uses electrical energy within ``neurons''. It switches between these electrical and chemical communication methods as needed.
• The complexity of the enteric nervous system : It is so complex that some experts consider it a separate part of the entire nervous system rather than part of the autonomic nervous system. This is because the enteric system contains as many neurons (the specialized cells that make up the brain, spinal cord, and nerves) as our spinal cord.

Where is this system located?

The autonomic nervous system is a network of nerves that runs throughout our head and body. Some of these nerves come directly from the brain. Others come from the spinal cord, which carries signals from the brain to those nerves.

Cranial Nerves

There are 12 types of cranial nerves, or ``Cranial Nerves''. These are separated and named by Roman numerals. The nerve fibers of our autonomic nervous system are found in 4 of these 12 cranial nerves. These are the third, seventh, ninth, and tenth cranial nerves. These control the dilation of the pupil, focusing the eye, tears, nasal mucus, saliva, and the functions of the organs in the chest and abdomen.

Spinal Nerves

Also, the autonomic nervous system uses most of the 31 spinal nerves. This includes the spinal nerves in our chest and upper back (thoracic), lower back (vertebral), and tailbone (sacrum).

It is through these spinal nerve connections that the autonomic nervous system controls these organs:

• Heart
• Lungs
• Liver
• Pancreas
• Spleen
• Stomach
• Small and large intestines
• Kidneys
• Bladder
• Genitals

Control center: Hypothalamus

The part of our brain that controls autonomic activity is the hypothalamus. Although it is not part of the autonomic nervous system itself, it is a very important part of how it functions.

What is this made of?

The autonomic nervous system is made up of the same cells as our entire nervous system. The main cell types are:

Neurons – messengers

These cells are what send and receive signals. They make up our brain, spinal cord, and nerves. They also switch between chemical and electrical signals.

Parts of a neuron:

• Cell body : This is the main part of the cell.
• Axon : This is a long, arm-like part of the axon. At the end of an axon are several finger-like extensions. This is where the neuron's electrical signal is converted into a chemical signal. These extensions, or synapses, connect with other nearby nerve cells.
• Dendrites : These are the small, branching structures on the cell body (the name comes from a Latin word meaning “tree-like”). These dendrites receive chemical signals from the synapses of other neurons.
• Myelin : This is a thin layer of fatty compounds. Myelin is a protective covering around the axons of many neurons.

The dendrites of a single neuron can connect to thousands of other synapses. Some neurons can be longer or shorter, depending on where they are in the body and the function they perform.

Glial cells – helpers of neurons

Glial cells (pronounced “gli-al”) do a lot of different jobs. They help neurons grow and develop when we’re young, and they also manage how neurons function throughout our lives. They protect our nervous system from infection, regulate the chemical balance of the nervous system, and myelinate the axons of neurons. There are about ten times more glial cells than neurons.

Nuclei and Ganglia – clusters of cells

• Nuclei : These are clusters of nerve cells that work in the same way or have the same connections.
• Ganglia: (pronounced “gang-lee-ya,” “gang-lee-on”) These are groups of interconnected nerve cells. Not all of the cells in these groups have the same function or the same connections, but they are generally located in the same area or connected to the same systems. For example, the cochlear and vestibular ganglia are involved in our senses of hearing and balance.

What are the common diseases that affect the Autonomic Nervous System?

There are many conditions and causes that damage or cause disease of the autonomic nervous system (this is called ``Autonomic Neuropathy''). Some common examples are:

• Type 2 Diabetes : Uncontrolled diabetes can damage the autonomic nervous system over time. For example, orthostatic hypotension occurs when blood pressure drops when standing. Diabetic neuropathy, which is nerve damage caused by diabetes, can affect the reflex that increases blood pressure when standing.
• Amyloidosis : In this condition, misfolded protein particles accumulate in various parts of the body, causing long-term nerve damage.
• Autoimmune and inflammatory conditions : A good example of this is Guillain-Barré Syndrome.
• Congenital and genetic conditions : These are diseases or conditions that are present at birth. Genetic conditions are inherited from parents. Hirschsprung's disease is an example of this.
• Infections : Nerve damage can be caused by viruses such as HIV, Lyme disease, or Chagas disease, which is caused by insect bites. It can also be caused by other infections such as botulism or tetanus.
• Multiple System Atrophy : This severe condition is similar to Parkinson's disease. Over time, it damages the autonomic nerves.
• Toxins and toxic substances : Toxic heavy metals such as mercury and lead can damage the autonomic nervous system. Many industrial chemicals can also cause this type of damage. Alcohol can also have toxic effects on the autonomic nervous system.
• Trauma : Accidents can cause damage to the nerves. This can be long-term or permanent. Injuries to the spinal cord, especially those that involve the lower autonomic nervous system, can damage or sever the connections that lead down the spinal cord.
• Tumors : Both cancerous and benign tumors can disrupt your autonomic nervous system.

What are the common symptoms of this condition?

Symptoms of autoimmune diseases depend on where the damage is. In conditions like type 2 diabetes, damage can occur in many parts of the body. Symptoms that are often seen when the autoimmune system is damaged include:

• Heart rhythm problems (including arrhythmias).
• Dizziness or loss of consciousness when standing.
• Difficulty swallowing (Dysphagia).
• Digestive problems (including gastroparesis).
• Constipation.
• Difficulty passing urine or stool (loss of bladder or bowel control – `Incontinence`).
• Sexual immorality.
• Excessive sweating (Hyperhidrosis) or lack of sweating (Anhidrosis).
• Difficulty tolerating hot weather.

What tests are available to check the health of the Autonomic Nervous System?

There are several tests that can help diagnose problems with the autonomic nervous system. Some of them include:

• Blood tests : These can detect a wide range of issues, from immune system problems to toxins and poisons (especially metals like mercury and lead).
• Electrocardiogram (EKG)
• Electroencephalogram (EEG) .
• Electromyogram (nerve conduction test) .
• Genetic testing .
• Magnetic Resonance Imaging (MRI) .

What are the treatments for this?

Treatment for autoimmune diseases can be very specific, depending on the disease. Some treatments address the disease itself or the underlying cause. Other treatments only treat the symptoms, especially when there is no cure or permanent treatment for the disease. This means that there is no “one-size-fits-all” treatment for these diseases. Medications can help with some diseases, but not all.

How to protect yourself from Autonomic Nervous System problems?

Preventing damage to the autonomic nervous system is the best way to protect yourself from diseases that affect it. The best preventive measures you can take are:

• Eat a balanced diet . Vitamin deficiencies, especially vitamin B12 deficiency, can damage your autonomic nervous system.
• Avoid drug and alcohol abuse . Abuse of both prescription and recreational drugs, as well as alcohol, can damage the autonomic nervous system.
• Stay physically active and maintain a healthy weight . This can help prevent or delay the onset of Type 2 Diabetes, which can damage the autonomic nerves over time. It can also help prevent injuries that can damage the areas of the spinal cord that affect the autonomic nervous system.
• Wear protective equipment when necessary . Accidents are a major cause of nerve damage. Wearing protective equipment at work and play can help protect you from these types of accidents, or at least reduce the severity of the accidents.
• Manage chronic conditions as recommended . If you have a chronic condition that can affect your autonomic nerves – especially type 2 diabetes – you should take steps to manage your condition. This can help limit the effects of the condition or delay the time it takes for it to get worse. Your doctor can guide you on ways to manage your condition.

Important : The autonomic nervous system is a very important part of how you live. Most of the time, you don't even have to think about it, it just does its job. Taking care of your body, especially your nervous system, is the best way to avoid diseases that damage the autonomic nervous system. Then you can focus on the things in your life that you want to focus on.

The most important thing we need to remember (Take-Home Message)

So, simply put, our Autonomic Nervous System is an amazing, automatic control system in our body. Even though we're not aware of it, it silently takes care of many essential things, from our breathing to our heartbeat to our digestion.

Keeping this system healthy is crucial to our overall health. Therefore, it is important to follow a healthy lifestyle, follow proper medical advice, and take care of our bodies . Because as long as this silent worker is working well, we are free to think about other things in our lives.