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The Nervous System – An Introduction

The Human Nervous System both keeps us alive and helps us navigate life to interact with our environment. It’s the ultimate supercomputer!

The Human Nervous System

The Human Nervous System defines us. It allows us to interact with and process the world around us. It is responsible for our subconscious bodily functions, psychological function, our sensory processing and movement.

In order to effectively manage and guide the body the Nervous System is divided into divisions and sub-divisions.

The Central Nervous System

The Parts of the Central Nervous System

The Central Nervous System (CNS) consists of the brain and spinal cord. The CNS is responsible for regulating bodily functions and processing and co-ordinating signals from the nerves. It also plays a role in mood, emotions and personality.

Peripheral Nervous System

The Parts of the Peripheral Nervous System

The Peripheral Nervous System (PNS) consists of all the nerves that exit the brain and spinal cord. These nerves send signals between the CNS and the rest of the body’s systems. The PNS is further divided into the Somatic and Autonomic Divisions.

Main Functions of the Peripheral Nervous System

The Somatic Nervous System

The Somatic Nervous System includes your 5 senses (sight, touch, taste, hearing and smell) and movement of the body. This includes walking, running, posture and subconscious actions like pulling your hand off a hot object. The Autonomic Nervous Systems is more complex and has further divisions.

Divisions of the Peripheral Nervous System

The Autonomic Nervous System

The Autonomic Nervous System operates subconsciously. It is made up of the Parasympathetic and Sympathetic Nervous Systems. These systems have opposing effects but also work together to keep the body in a state of homeostasis (equilibrium). The Parasympathetic Nervous System is in charge of functions that maintain energy and heal. It has been referred to as the ‘rest and digest system‘ but would be better referred to as ‘a housekeeping system’. The Sympathetic Nervous System has been referred to as your ‘fight or flight system‘. It stimulates the body to prepare for and react to stress. This includes internal, external, psychological and emotional stresses.

Actions of the Parasympathetic and Sympathetic Nervous System on the Organs

Disorders of the Nervous System

The Nervous System can be injured or suffer dysfunction in many ways. These disorders all affect the ability of the Nervous System process to send and receive signals within the body.

Structural Disorders

Structural disorders consist of injury directly to the nerves or brain.

Examples of this are:

  • Traumatic Brain or Spinal Cord injury, due to trauma, car accidents, falls etc.
  • Tumours of the Brain and Spinal Cord
  • Pinched or Compressed Nerves.

Vascular Disorders

Vascular disorders occur when blood flow is disrupted to the nerve often leading to nerve cell death.

Examples of these are:

  • Stroke or Cerebrovascular Accident (CVA) – Blood flow in brain disrupted due to a rupture or blockage of the vascular structures
  • Transient ischemic attack (TIA) – temporary disruption of blood flow in brain
  • Any haemorrhage or bleeding in the brain
  • Decreased blood flow to peripheral nerves such as in peripheral vascular disease.
Functional Disorders

Functional disorders occur when there is a chemical dysfunction where the brain is sending or receiving signals via neurotransmitters or hormones.

Examples of these are:

  • Epilepsy
  • Dizziness
  • Neuralgia
  • Depression.
Degeneration Disorders

Degenerative disorders consist of damage to the structure of the nervous systems from genetic or environmental causes. Examples of this are; Parkinson’s Disease, Multiple Sclerosis (MS) and Alzheimer Disease.

Infections Disorders

Infections such as meningitis, encephalitis, polio and various viruses or bacteria can disrupt the normal function of the nervous system. The infection can cause either damage to the nerve cell directly or inflammation around it which impedes the nerve’s ability to transmit signals.

Signs and Symptoms of Nervous System Disorders

There are quite a few common signs and symptoms of nervous systems disorders. However, some of these may also indicate problems in other systems of the body. It is important to remember that individuals react differently to changes in the body or the environment. This means that different people may experience symptoms of a higher or lower intensity from a the same disorder. It also means that people with the same disorder often experience a different collection of symptoms to each other.

  • Sudden or persistent headaches
  • Pins and needles, tingling, throbbing or crawling sensations
  • Loss of strength or numbness
  • Loss of sight, double or blurry vision
  • Memory loss or slower cognitive function
  • Loss of coordination
  • Muscle spasms
  • Seizures or tremors
  • Pain that radiates from the back or neck to other parts of the body
  • Slurred speech or language impairment
  • Emotional or Behavioural changes
  • Fatigue


Until recent years Pain has not been fully understood by science. Pain is essentially a function of the Nervous System. In fact, it’s a very important one.

The function of experiencing pain falls under the division of the CNS. The PNS sends signals to the brain to inform it that something has occurred within or to the body. The CNS then evaluates the signal by taking into account the environment, area and intensity of the signal and past experience. The brain will then respond by creating pain as a protective output.

The Cartesian pain model

Once the brain has processed all this information it sends a response via the PNS. This response contains two basic parts: sensation and action.

if the brain determines the signal is harmless and maybe just ticklish the body laughs and tries to get away from the stimulus but not urgently. If the brain decides that the stimulus is harmful the body sends pain and causes bracing and/or the urgent need to get away from it in order to avoid injury or survive.

This reaction is healthy and is one of the body’s main defense mechanisms. However, the brain can misinterpret signals of the body or even create pain purely based on environment and past experiences. This causes pain to become persistent or chronic and an offender in the body instead of a defender. Stress, surgery, or long term unresolved pain can cause this reaction. Stress may often amplify pain because your CNS is already on high alert. You can read more about Pain here.

How to Manage your Nervous System

The Nervous system is our very own supercomputer. It runs all the background processes and conscious tasks needed for us to stay alive, navigate life and interact with our environment. Similarly, to the rest of the body’s systems and structures, it is a lot more resilient than we often give it credit.

To keep this system healthy, it’s important to live a healthy and active lifestyle. Movement and exercise challenge the brain to create new connections and release hormones that affect mood and physical health. It’s also important for blood flow and physical movement of the nerves in the body.

Diet is an important factor. The nervous system needs lots of complex carbohydrates and water to function effectively. Food and drinks with sugar, caffeine and alcohol directly affect your neurotransmitters and disrupt the body’s natural processes of communication. Neurotransmitters are the messengers that the Nervous System uses to talk to the body.

Sleep is also extremely important as this is when your body recycles neurotransmitters. If there are not sufficient neurotransmitters ready to be used when you wake up, you are effectively running on empty. This will eventually cause an overload of your nervous system and may lead to pain, anxiety and a weakened immune system.

Stress is another factor that can negatively affect how your nervous system functions. It is important to apply stress management strategies daily. This could include deep breathing, mindfulness, meditation and good time management skills.


It is important to remember to maintain a balanced lifestyle, to ensure that you keep your body healthy. The Nervous System is often a forgotten member of the team. Do not let that happen to you.

Your Physiotherapist can help you by assessing your nervous system and lifestyle. To create a plan to either aid in healing or keep it functioning optimally to a ripe old age.