We are all familiar with pain. Naturally it's something we want to avoid. But pain does have a positive role - it warns us when we're in danger, sick or injured so that we can take evasive action or seek medical help.
Our ability to feel pain is part of the way we interact with the workings of our bodies and interact with the outside world. Through experiencing pain and recalling the event, we learn to avoid things that are potentially harmful and unpleasant.
In fact, feeling pain is vital to our well-being. This is evident when the whole body or parts of it lose the ability to detect the pain sensation. In leprosy sufferers, for example, the nerves to the hands and feet are often damaged and, as a result, they continually injure their hands and feet without feeling any pain.
The type of pain we experience depends on what is causing it. It also depends on the way in which pain signals are interpreted and analysed by the nervous system.
For instance, if you're seriously ill, severe pain can arise from the persistent presence of some harmful stimulus in our bodies. But it can also occur as a result of a malfunction of the nerve fibres that relay our pain messages.
Though pain is distressing, it can provide a vital clue to diagnosis. The type of pain, its character and the position can enable doctors to detect the cause of the complaint and decide on suitable treatment.
THE PAIN ROUTE
Pain messages are triggered by painful stimuli both inside and outside our bodies. These stimuli excite unspecialized nerve endings in the skin and elsewhere.
The nerve endings are attached to two types of nerves that connect with the spinal cord, the organ responsible for the initial analysis of our pain sensations. One type of these nerve endings will relay information very rapidly, the other less so. This helps us to distinguish betwe8n two types of pain: that which needs to be reacted to immediately, such as a burning pain, and that which doesn't, such as a dull ache.
The nerve endings continue to make contact with the network of nerve fibres in the spinal cord until the information is more organized.
It is then relayed to the thalamus, the special area in the brain which processes information from skin receptors. The thalamus sends the message on to the cerebral cortex which makes the final analysis. The brain also considers our emotional state before it finally decides how to perceive the painful stimuli.
NOT ALL THE SAME There are different types of pain. For instance, skin pain is usually localized and may be of a pricking or burning quality. Internal pain is more variable, but tends to be less localized and is perceived as deeper and often duller.
'Referred pain' originates in one organ or area but is felt in another. This is because the messages from these organs are received and analysed by parts of the spinal cord that also deal with the areas where the pain seems to be coming from.
For example, pain coming from the heart may be felt in the chest but also in the jaw and left arm, as the pain messages spill over in their spinal analysing centres into neighbouring zones.
When an arm or a leg has been amputated, the nerves remain in the stump. Initially, the brain will register pain from the stump as if it were coming from the lost limb. This phenomenon is known as 'phantom pain'. After a while, however, the brain usually reorganizes its perceptions so that any pain felt from the stump actually comes from there.
HOW THE BRAIN REACTS TO PAIN
Nerve endings send pain messages to the brain for analysis via the spinal cord. This can be done either quickly or slowly.
Thalamus - grey matter processes information from skin receptors
Cerebral cortex - makes final analysis of pain messages
Pain messages sent on fast route to the brain
Pain messages analysed by spinal cord while on slower route to the brain
Medulla where analysis of pain begins
Cerebral spinal cord
ALL IN THE MIND?
Your state of mind is an important factor in your perception of pain. For example, a soldier who has been seriously injured in battle may feel no pain because his mind is focused on fighting. When the battle is over, the pain may be unbearable, even though the injury is exactly the same.
In India, practitioners of yoga are able to avert their minds from pain by contemplating other things. As a result, they can achieve great feats of endurance, such as lying on a bed of nails. In cases like this, it's thought the brain is somehow prevented from acknowledging the unpleasant significance of the pain messages it receives.
The other side of this coin is the detrimental psychological effects pain can have on us. Prolonged severe pain progressively erodes our mental ability to cope with it. As a result, our personality appears to change as we focus more and more on the pain and perceive it as getting increasingly worse. So it is therefore wrong to dismiss pain as being only in the mind.
Depending on its location, intensity and duration, pain can provide a vital clue to diagnosis.
'Phantom pain' frequently occurs after amputation. The brain continues to register pain in the stump as if it were coming from the lost limb.
Taken from THE HEALTH FILE A Complete Medical Encyclopedia, A MARSHALL CAVENDISH REFERENCE COLLECTION by DR JOHN CORMACK, WEEKLY Australia, New Zealand, Malaysia Singapore Malta RSA Other Countries Namibia, in the following categories TESTS AND TREATMENT Pg 15, NATURES CLINIC Pg 7, MEDICAL MATTERS Pg 17, BODY BASICS Pg A Z, M MEDICHECK Pg 9, INSIGHT Pg 11, CHILD HEALTH Pg 11, EMERGENCY ACTION Pg 9
DR JOHN CORMACK, BDS MB BS MRCS LRCP, is the medical consultant to The Health File. The senior partner in an Essex based practice, he is also a member of the General Medical Council and has written for numerous magazines and newspapers as well as for the medical press. He is a regular broadcaster on television and radio and has scripted a number of award-winning educational videos.
Note: Where gender is unspecified, individuals are referred to as 'he', This usage is for convenience only and not intended to imply that all doctors and patients are male. Medicheck charts are only a rough guide to diagnosis, Always seek medical advice if you have worrying symptoms.
Copyright Marshall Cavendish 1995, Printed in Great Britain, Published by Marshall Cavendish Partworks Ltd, 119 Wardour Street, London WIV 3TD
(Due to the urgency of education on this site, spelling will be corrected at a later stage.All photos and charts in the script have been left out).
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