Nature has equipped you with a mega-sophisticated computer that processes information, makes critical decisions and acts in a fraction of a millisecond – known as your nervous system.
Your body's main control structure
This supercomputer involves your brain, your spinal cord, sensory organs and all the nerves that connect these organs with the rest of your body.
The nervous system is a remarkably intricate set of specialised nerve cells (also known as nerve fibres or neurons) that transmit signals between different parts of your body.
Acting as your body’s main control structure, this vast neural network keeps you informed about the world outside and inside, allowing you to react to it. It controls and/or monitors every tissue, every muscle and physical sensation.
Your nerves can be compared to a computer’s hardware that communicates decisions with the rest of your body, while the brain, with its around 100 billion neurons, is like your body’s processing software – it sends millions of electrical signals per second through your spinal cord at a speed of over 273km/h.
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Employing the nervous system to communicate with each of your body’s 70,000 trillion cells, your brain processes information and makes vital decisions to keep you alive without ever taking a rest. It is also critical for awareness, movements, speech, thoughts, sensations and memory.
What your nervous system does for you
The nervous system is involved in many, but not all of your body’s important functions, comments medical physiologist Dr Derick van Vuuren of Stellenbosch University. Indeed, various nervous system pathways are involved in maintaining posture and the body’s “fight or flight” defence mechanism, but “other communication networks mostly control key processes like red blood cell production, immune function and energy metabolism”.
The nervous system’s three main functions are to:
1. Perceive your environment (e.g. tasting food or checking the temperature of a hot beverage).
2. Make decisions regarding the input from the surroundings. These decisions, which are the job of the central nervous system (CNS), vary from aspects you think about (e.g. deciding if you like that sushi) to automatic responses you don’t think about (for example opting to jerk your hand away from the stove, or becoming thirsty when your body needs water).
3. Initiate the “action-ing” of decisions, i.e. telling your muscles or organs to respond and “do” things in a certain way. This includes fairly simple yet precise actions like buttoning your shirt, to much more complex behaviour like deciding whether you’re going to give a clever response to a Facebook post.
Dr van Vuuren says all three functions rely on the ability of your nerve fibres to generate small electrical “flashes” (action potentials). “In this way, the nervous system is basically your body’s high-speed communication network and decision-making hub.”
The body’s defence mechanism
Ever faced a threatening situation? You felt that pounding heart, dry mouth, fast breathing and all your senses on high alert. Your sympathetic nervous system deserves all the credit for your ability to instantly fire on all cylinders, diverting blood to your muscles and lungs, releasing adrenaline and other stress hormones and revving up your breathing and heart rate.
Maintaining your posture
So what does posture have to do with your central nervous system? It turns out that if you don’t have good posture and spinal alignment, it can’t function properly. Dr van Vuuren explains that “the somatic nervous system controls skeletal muscle contraction, while the interactions between skeletal muscles determine posture”.
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Although there are natural curvatures in our vertebral column, orthopaedic experts stress that having “a neutral posture” (in which the muscles of the body must be in balance to support an aligned spine), is much more important than you think. That’s because a neutral posture not only maintains your body in an upright position, but also supports it against gravity.
If you have any misaligned posture, especially in the neck and head areas, it may affect the flow of blood and energy from your body’s core to the brain. That, in turn, could affect many mental functions like memory, cognitive ability and concentration.
When your nervous system goes haywire
Even the most sophisticated computers have glitches, and it’s no different with the central nervous system. Scientists admit the more they study the body’s intricate nervous system, the more they recognise that they’re “only at the tip of the iceberg in understanding its complexities”.
Trauma, infection, autoimmune disorders, a tumour or stroke can all affect your brain or spinal cord. Nervous-system disorders include Parkinson’s disease, multiple sclerosis, Alzheimer’s disease, other types of dementia and meningitis.
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“Everything in your body is connected, so if something goes wrong with one aspect or part of the body, it will influence other parts as well, including the nervous system,” asserts Dr van Vuuren.
Peripheral nerve damage (neuropathy) affects millions of people worldwide. This condition affects the peripheral nervous system sending sensory information between the CNS and every other body part. With more than 100 types of peripheral neuropathy, symptoms vary from tingling or numbness, to muscle weakness, prickly sensations or severe pain.
How diabetes can affect your nerves
In people with diabetes, a common form of nerve damage is called diabetic neuropathy. Although diabetes mostly affects your metabolism, Dr van Vuuren cautions that if left untreated, the associated high levels of blood sugar (glucose) can “damage areas of the nervous system such as sensory nerves over time”. Typical diabetic neuropathy signs include pain, burning, tingling or numbness in both feet. These gradually progresses up the legs, and later spread to the fingers, hands and arms.
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With the nerves to your feet being the longest in your body, they’re often affected the most, which is why he urges people with diabetes to have regular foot checks with their doctor.
How your nervous system and its vital components work
The nervous system comprises the central nervous system (CNS) and the peripheral nervous system (PNS).
- The CNS, consisting of the brain and spinal cord, provides your body’s processing, memory and regulation systems.
- The peripheral nervous system (PNS) is a huge network of spinal and cranial nerves outside the CNS. Like an information highway, it carries signals between the brain and spinal cord and other areas like muscles, organs and glands to regulate their functions.
The PNS then branches into the somatic nervous system and the autonomic nervous system that function together.
- The somatic system regulates voluntary functions involving the skin, bones, joints, and skeletal muscle. It’s called voluntary because your brain has control over deliberate movements like throwing a ball or writing.
- The autonomic system affects internal organs like the heart, lungs, liver and stomach. It controls many automatic (involuntary) body functions and processes like breathing, heartbeat, digestion and blood pressure that occur with little or no conscious involvement or effort on your part.
The autonomic system is itself divided into two parts: the parasympathetic and sympathetic nervous systems. They function by opposing each other in a mutually beneficial way, so when one is dominant, the other is quiet.
- The parasympathetic system is the “rest and digest” part. It helps your body save energy and restore balance or homeostasis after a stressful situation. When you’re relaxed with no emergency in sight, this system automatically decreases your blood pressure, slows your heartbeat and breathing and increases digestion.
- The sympathetic system is your nervous system’s “fight or flight” component. It kicks into gear when you face danger or your body has to rev itself up for intense physical or emotional activity (exercise, stress, excitement or even embarrassment).
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Dr Derick van Vuuren, Medical physiologist, Faculty of Medical and Health Sciences, Stellenbosch University.