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  • Writer's pictureDavid Hurley

The Autonomic Nervous System

A lot of the subjects that I write about are concerning the way that our bodies move, injuries, pain and how we fuel this machine that we inhabit.

The subject this week is about one of the automated systems inside us, that works completely and utterly automatically adjusting the way that we work to keep us functioning and alive.

Fascinating stuff – Welcome to The Autonomic Nervous System.

Autonomic Nervous System (ANS):

Your autonomic nervous system is a network of nerves throughout your body that control unconscious processes. These are things that happen without you thinking about them, such as breathing and your heart beating. Your autonomic nervous system is always active, even when you’re asleep, and it’s key to your continued survival.

Your autonomic nervous system controls your body’s automatic processes, with divisions to activate processes and relax them, it manages body processes you don’t think about, those processes include heartbeat, blood pressure, digestion and more.


So what is the autonomic nervous system?

Your autonomic nervous system is a part of your overall nervous system that controls the automatic functions of your body that you need to survive,  these are processes you don’t think about and that your brain manages while you’re awake or asleep.

Your overall nervous system includes two main subsystems:

Central Nervous System: This includes your brain (your retina and optic nerve in your eyes are considered part of your brain, structure-wise) and spinal cord.

Peripheral Nervous System: This includes every part of your nervous system that isn’t your brain and spinal cord, so touch and feel, sensation, taste etc.

Now it gets even more complicated.

Your peripheral nervous system also has two subsystems:

Somatic Nervous System: This includes muscles you can control, plus all the nerves throughout your body that carry information from your senses. That sensory information includes sound, smell, taste and touch. Vision doesn’t fall under this because the parts of your eyes that manage your sight are part of your brain.

And, wait for it ……….

The Autonomic Nervous System: This is the part of your nervous system that connects your brain to most of your internal organs.


So what does the autonomic nervous system do?

Your autonomic nervous system breaks down into three divisions, each with its own job:

Sympathetic Nervous System: This system activates body processes that help you in times of need, especially times of stress or danger. This system is responsible for your body’s “fight-or-flight” response.

Parasympathetic Nervous System: This part of your autonomic nervous system does the opposite of your sympathetic nervous system. This system is responsible for the “rest-and-digest” body processes.

Enteric Nervous System: This part of your autonomic nervous system manages how your body digests food.

So how does the autonomic nervous system help with other organs?

Much like a home needs electrical wiring to control lights and everything inside that needs power, your brain needs the autonomic nervous system’s network of nerves. These nerves are the physical connections your brain needs to control almost all of your major internal organs.

Your autonomic nervous system has the following effects on your body’s systems:

Eyes: Your ANS doesn’t involve your vision directly. However, it does manage the width of your pupils (regulating how much light enters your eyes) and the muscles your eyes use to focus.

Lacrimal: (eyes), nasopharyngeal (nose) and salivary (mouth) glands: Your ANS controls your tear system around your eyes, how your nose runs and when your mouth waters.

Skin: Your ANS controls your body’s ability to sweat. It also controls the muscles that cause hair to stand up. This reaction is commonly called “goosebumps” or “gooseflesh.”

Heart and circulatory system: The ANS regulates how fast and hard your heart pumps and the width of blood vessels. Those abilities are how your autonomic system helps manage your heart rate and blood pressure.

Immune system: Your parasympathetic nervous system can trigger reactions from your immune system. That can happen with infections, asthma attacks and allergic reactions, to name a few.

Lungs: Your ANS manages the width of your airway and the network of passages that carry air into and out of your lungs.

Intestines and colon: Your ANS manages the digestion process from your small intestine to your colon. Your autonomic nervous system also holds the muscles closed at your rectum until you’re ready to relieve yourself and defecate.

Liver and pancreas: Your ANS regulates when your pancreas releases insulin and other hormones, and when your liver converts different molecules that hold stored energy into glucose that your cells can use.

Urinary tract: Your ANS manages your bladder muscles, including the muscles that hold it closed until you're ready to relieve yourself and urinate.

Reproductive system: Your ANS plays a key role in your body’s sexual functions, including feeling aroused (erections and secreting fluids that provide lubrication during sex) and the ability to orgasm.

What are some interesting facts about the autonomic nervous system?

Your sympathetic and parasympathetic systems create a balancing act. Your sympathetic nervous system activates body processes, and your parasympathetic deactivates or lowers them. That balance is key to your body's well-being and your ongoing survival.

It involves multiple forms of communication. Your nervous system uses chemical compounds produced by various glands in your body and brain as signals for communication. It also uses electrical energy in the neurons themselves. The neurons switch back and forth between electrical and chemical communication as needed.

Your enteric nervous system is very complex. Some experts describe it as part of the overall nervous system instead of the autonomic nervous system. That’s because there are as many neurons (specialized cells that make up your brain, spinal cord and nerves) in your enteric nervous system as there are in your spinal cord.


Conditions and Disorders:

There are many conditions and causes of autonomic neuropathy, which means damage or disease that affects your autonomic nervous system. Common examples include:

Type 2 diabetes: Unmanaged type 2 diabetes can damage your autonomic nervous system over time. An example of this is orthostatic hypotension, where your blood pressure drops when you stand up. Diabetic neuropathy can damage the nerves that normally trigger a blood pressure increase reflex when you stand.

Infections: Nerve damage can happen because of viruses such as HIV or bacteria from insect bites that cause Lyme disease or Chagas disease. Other infections that can also do this include botulism or tetanus.

Poisons and toxins: Toxic heavy metals like mercury or lead can damage autonomic nerves. Many industrial chemicals can also cause this kind of damage. Alcohol can also have toxic effects on your autonomic nerves.

Trauma: Injuries can cause nerve damage, which may be long-term or even permanent. This is especially the case when you have injuries to your spinal cord that damage or cut off autonomic connections farther down.

Tumors: Cancer and benign (harmless) growths can both disrupt your autonomic nervous system.


These are just a few conditions that can affect the functioning of the Nervous System, if you feel you have any of these or any other health concerns you must see a medical practitioner immediately.

As you can see from the above detail our Nervous System is hugely complicated. But combined all our nerves are the basic wiring and communication channels throughout our bodies. Keeping us functioning, healthy, moving and safe, weather we know it or not.

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