The nervous system, the information highway of the body, is made up of nerves—bundles of interconnected neurons which carry messages (hormone signals) that create responses from their targets. The central nervous system (CNS), made up of the brain and spinal cord, is the major controller of the body’s functions, charged with interpreting sensory information and responding to it with its own directives. The CNS interprets information coming in from the senses, formulates an appropriate reaction, and sends responses to the appropriate system to respond accordingly. Everything that we see, hear, smell, touch, and taste is conveyed to us as neural impulses and causes our voluntary and involuntary reactions. The responses can also begin in our brain, with no outside input, just as a reaction to a thought or emotion.
There are a few sub categories to the CNS, the main ones being the Autonomic Nervous System, and the Endocrine System
The Autonomic Nervous System (ANS).
If our body is a performance car, and our cells are what makes up our physical chassis (all things you can touch and see) then our Autonomic Nervous System (ANS) is all the electrical and computer data that is invisible, yet controls everything. It silently regulates our fuel injection, power steering, responsive suspension, audio levels, climate control, automatic windscreen wipers and headlights, etc.
It is as wonderfully simplistic as it is complicated. Put simply, a reaction causes a response, and that response causes another, so on and so on. Easy. Yet it is the complexity of these signals and paths they take which makes it a rabbit warren of pathways that links back on itself and can cause a damaging feedback loop if we constantly perceive a stressful environment, or conversely, don’t give ourselves any signals that the system can relax. Everything is connected in an intricate web of involuntary responses.
The Autonomic Nervous System controls the muscles of internal organs (such as the heart) and glands. One side of the autonomic nervous system helps the body rest, relax, and digest food, regenerate, and the other side helps a person fight or take flight in an emergency.
Our rest and relax signals come from our Para-sympathetic Nervous System (PNS).
Our fight or flight response is our SYMPATHETIC Nervous System (SNS).
To remember which is which, think of your ‘fight or flight’ response as being “sympathetic” in reaction to a stressful situation. It is there to protect you and keep you alive when a lion jumps out at you. It sympathises with you and makes you more alert and more able to deal with the situation. Nowadays that “lion” is present all day every day in the form of emotional or physical stress, and often completely avoidable and self-inflicted.
The sympathetic nervous system prepares your body for physical and mental activity. It makes your heart beat faster and stronger, opens your airways so you can breathe more easily, and inhibits digestion. Hence why a stressful action movie, drama, or thriller are not good choices for dinner viewing. Even many comedies are based on anxiety, yelling, anger and other SNS stimulating inputs, which will also inhibit optimal absorption of nutrients and release of hormones to help you recover during sleep.
The parasympathetic nervous system is responsible for bodily functions when we are at rest: it stimulates digestion, activates various metabolic processes and helps us to relax. But the sympathetic and parasympathetic nervous systems do not always work in opposite directions; they sometimes complement each other too.
The role of the ANS is to constantly fine-tune the functioning of organs and organ systems according to both internal and external stimuli. The ANS helps to maintain homeostasis (internal stability and balance) through the coordination of various activities such as hormone secretion, circulation, respiration, digestion and excretion. The ANS is always “on” and functioning unconsciously, so we are unaware of the important tasks it is performing every waking (and sleeping) minute of every day.
| ANS | Sympathetic | Parasympathetic |
| Function | To defend the body against attack | Healing, regeneration, re-balancing homeostasis after stress. |
| Body Functions It Activates | Raises blood pressure and blood sugar, and increases heat production | Activates digestion and the immune system |
| Psychological Qualities | Fear, guilt,
sadness, anger, and aggressiveness. |
Calmness, contentment, gratitude and relaxation |
| Factors That Activate This System | Stress, fears, anger, worry, excessive thinking & stressful exercise | Rest, sleep, relaxation therapies and feelings of being loved |
Endocrine system
A large part of the reactions caused by the ANS are from signals it gives to the Endocrine System. Your endocrine system includes all the glands in your body that make hormones. These chemical messengers play a key role in making sure your body works the way it should.
If your endocrine system isn’t healthy, you might have problems developing during puberty, getting pregnant, or managing stress. You also might gain weight easily, have weak bones, or lack energy.
A gland in the endocrine system is made up of groups of cells that function to secrete hormones. A hormone is a chemical that moves throughout the body to help regulate cellular behaviour. When the hormones released by one gland arrive at receptor tissues or other glands, these receiving receptors may trigger the release of other hormones, resulting in a series of complex chemical chain-reactions. The endocrine system works together with the nervous system to influence many aspects of human behaviour, including growth, reproduction, emotions, brain activity, and metabolism.
The pituitary gland, a small pea-sized gland located near the centre of the brain, is responsible for controlling the body’s growth, but it also has many other influences that make it of primary importance to regulating behaviour. The pituitary gland secretes hormones that influence our responses to pain as well as hormones that signal the ovaries and testes to make sex hormones. The pituitary gland also controls ovulation and the menstrual cycle in women, fluid and mineral balance, and the stress response.
Because the pituitary has such an important influence on other glands, it is sometimes known as the “master gland.”
Other glands in the endocrine system include;
The pancreas, which secretes hormones designed to keep the body supplied with fuel to produce and maintain stores of energy and is responsible for one of the most chronically over-used (from High GI diets) hormones, insulin.
The pineal gland, located in the middle of the brain, secretes melatonin, a hormone that helps regulate the wake-sleep cycle.
The thyroid and parathyroid glands are responsible for determining how quickly the body uses energy and hormones, and controlling the amount of calcium in the blood and bones.
And that’s it. You made it through the boring stuff. Don’t worry, you don’t need to remember any of those details, it’s just an overview to convince you that everything is connected, and that is the one thing you do need to remember!
You, your body, your conscious and subconscious, everything you are, is just a group of cells that talk to one another via chemical/hormonal/electrical signals in response to the environment around them. Their responses are 100% controlled by you, that is the only information they get, either by what you experience physcially, or by your perception of the world you live in.