Put simply, sensory nerves send impulses about what is happening in our environment to the brain via the spinal cord. The brain sends information back to the motor nerves, which help us perform actions. How does a sensory nerve in the peripheral nervous system know this is any different than something like a soft toy? Different sensory nerve fibers respond to different things and produce different chemical responses which determine how sensations are interpreted.
Some nerves send signals associated with light touch, while others respond to deep pressure. Special pain receptors called nociceptors activate whenever there has been an injury, or even a potential injury, such as breaking the skin or causing a large indentation.
Now, an impulse is heading through the nerve into the spinal cord, and eventually all the way to your brain. This happens within fractions of a second. Your spinal cord is a complex array of bundles of nerves, transmitting all kinds of signals to and from the brain at any given time.
It is a lot like a freeway for sensory and motor impulses. But your spinal cord does more than act as a message center: it can make some basic decisions on its own. An area of the spinal cord called the dorsal horn acts as an information hub, simultaneously directing impulses to the brain and back down the spinal cord to the area of injury. The brain does not have to tell your foot to move away from the rock because the dorsal horn has already sent that message. Even though the spinal reflex takes place at the dorsal horn, the pain signal continues to the brain.
This is because pain involves more than a simple stimulus and response. Simply taking your foot off the rock does not solve all of your problems. No matter how mild the damage, the tissues in your foot still need to be healed. In addition, your brain needs to make sense of what has happened.
When the pain signal reaches the brain it goes to the thalamus, which directs it to a few different areas for interpretations. A few areas in the cortex figure out where the pain came from and compare it to other kinds of pain with which is it familiar.
Was it sharp? Did it hurt more than stepping on a tack? This is caused by abnormalities in the system that carries and interprets pain — the problem may be in the nerves, spinal cord or brain. Neuropathic pain is felt as a burning, tingling, shooting or electric sensation. One form of neuropathic pain is associated with shingles — a skin condition caused by varicella zoster virus.
The virus triggers inflammation of the nerves and this inflammation can set off a constant deep aching, tingling or burning sensation that in some people can persist for months after the shingles rash has resolved.
People with neuropathic pain may feel pain from stimuli that are not normally painful, such as light touch or cold. They can also be more sensitive than normal to stimuli that are usually painful. For example, bedclothes touching the affected area could feel painful, and a pin prick could feel excessively sharp. This type of pain is caused or worsened by psychological factors. Often the pain has a physical cause, but the degree of pain and disability are out of proportion to what would be experienced by most people with a similar disorder.
This does not mean that the pain is not real, even if a physical cause cannot be found. Any kind of pain can be complicated by psychological factors. This is short-lived pain warning the body that damage is occurring. It is a symptom of injury or disease at the tissue level, and tends to resolve as the injury or disease does.
Chronic pain also called persistent pain can be caused by ongoing tissue damage, such as in osteoarthritis. However, in some cases no physical cause for the pain can be found or pain persists long after the injury has healed. In many cases chronic pain is a disorder in itself rather than being the symptom of a disease process. Chronic pain can persist for months or even years after an initial injury and can be difficult to treat.
People with chronic pain may experience sleeplessness, anxiety and depression, all of which can compound the problem. However, support and help are available, often in the form of a multidisciplinary approach, as carried out in pain management clinics. Chronic pain is an area that is being researched intensively, with the hope of relieving this distressing condition in the future.
Merck Manual Home Health Handbook. Overview of pain updated Aug Types of pain updated Aug Physiology and pathophysiology of pain revised September In: eTG complete. Melbourne: Therapeutic Guidelines Limited; Nov. Types of pain revised February Skip to content. You prick your finger on something sharp. Pain starts at the source of an injury or inflammation, whether it's your toe or your lower back. When you injure yourself, the body's automatic response is to stimulate pain receptors, which in turn release chemicals, says Dr.
The spinal cord carries the pain message from its receptors all the way up to the brain, where it is received by the thalamus and sent to the cerebral cortex, the part of the brain that processes the message. In other words, the physical message from the injury travels from where you're hurt directly to your brain, where it registers the sensation known as pain. Your brain perceives that pain, and sends the pain message back to the area of your body that hurts — and it all goes very quickly.
You don't stub your toe and notice that it hurts five minutes later; you know right away. There are different types of pain — more than just mild and severe — that can affect the way that you feel and perceive pain. Acute pain is short-term pain, usually what you experience after some sort of accident or injury — you break your arm or drop a can of soup on your foot. Once that injury has healed, your pain disappears and doesn't require further treatment.
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