No one likes pain. Yet it is a constant part of the human sensory experience. Yet, why are we able to feel pain? How does pain affect us? Does everyone feel pain the same way? As much as we don’t want to admit it, pain plays a very important role in our lives. Without pain, we might not even feel that we are hurt, and we would not avoid things that cause harm to our organism, such as fire, electricity, knives, etc. Pain exists for a reason, and its mechanism of action is relatively clear, so we will answer your questions below.
Why is pain painful?
Pain is a very complex and multifaceted process. Nature has been carefully designed to make animals feel pain when they should feel pain and hurt to the appropriate degree – for animal self-preservation, this should be the most perfect step in evolution, and animals that would not protect themselves must have become extinct long ago.
Simply put, pain is a self-defense mechanism that has evolved over time, and it gives creatures a warning of injury, allowing them to protect their bodies from further harm. It is also the most effective (though somewhat cruel) way for creatures to respond quickly to threats – and this “pain reflex” is supposed to be a big reason for the existence of pain.
Anyone who has accidentally touched a frying pan or oven is familiar with this pain reflex; in this case, the instinctive reaction to remove your hand is so natural that you can’t even think about it. The pain reflex is a life-saving mechanism, and based on this characteristic, pain has been passed down from generation to generation as a powerful genetic trait.
Some biologists have wondered why animals have evolved pain as a stress mode and not other responses. The reactions caused by pain are often violent, such as running away, resisting or shouting, and seem to be a sign of over-evolution. Can’t nature come up with other, gentler, less torturous methods?
According to evolutionary biologist Richard Dawkins, the answer to this question is no. In his book “Evidence for Evolution”, he writes that pain is the most effective way in evolution for organisms to quickly understand a dangerous situation and respond accordingly. And, as we can all feel, the more intense the pain, the more intense the feedback from the body.
Dawkins believes that the previously mentioned “red flags,” “red lights,” or whatever they are called, do not serve the same purpose, and that it is easy for an animal to underestimate the situation it is facing, even when it is already in danger. In this regard, Dawkins believes that the most “successful” creatures are those that can produce the necessary pain in the face of danger – and the degree of pain is impossible to ignore.
These stress responses in animals are reflected in humans as well. Some studies have shown that people who are naturally dull to pain live shorter lives on average. So whether we like it or not, we all need pain.
How do you classify pain?
Pain comes in different types and intensities. The most common type of pain is what is called “injury-receptive pain,” which is simply a direct response to a physical injury. When you step on your toe, get burned by a cigarette or mosquito, or cut your hand, you activate this type of hurt receptor (more on this in the next section).
Another big category is neuropathic pain, which is caused by an injury to the nervous system. It is also this injury that can cause a numbness, electric shock sensation or pins and needles sensation. This is also what you feel when you press hard on the inside of your elbow joint (the ulnar end of the elbow, called the “numb tendon” when you were a child).
In addition, there is also neuropathic pain, which is represented by phantom limb pain, which means that the patient feels that the severed limb is still present and that pain occurs in that area. The pain is mostly found distal to the severed limb, and there are many different pain properties. There is another type of pain that is more interesting, called anosognosia, for example, an athlete who may not feel pain after an injury during training or competition, and only after rest will he or she realize that he or she has suffered a very severe trauma. Finally, in terms of the course of the disease, there is a distinction between acute pain and chronic pain. People with rheumatoid arthritis probably experience chronic pain the most.
The mechanism of action of pain?
As previously noted, the neurobiological basis of pain is very, very complex. Essentially there are four mechanisms that must work together to produce pain: nerve fibers, pain receptors, the spinal cord, and the brain.
Our bodies are equipped with different sensory nerve fibers that respond to different types of stimuli, such as a gentle touch, a drop of wax on the back, being stuck with a needle, being flushed with water, etc. Depending on the degree of physical contact, our nerve fibers produce different chemical reactions, and it also influences the human brain’s interpretation of sensations.
When we are hurt, we activate pain receptors. These nerve fibers have a single purpose; their only function is to “alert” pain receptors. Essentially, the principle of how we feel pain is similar to an electrical circuit. When our foot kicks a table leg or our hand is cut by a razor blade, the pain receptors are activated and produce an electrical signal that travels along the nerve to the spinal cord, which in turn transmits the electrical signal to the brain. It takes only a fraction of a second to complete this process: these electrical signals are transmitted to all parts of the body at a speed of about 1m/s.
The electrical signals first enter the thalamus, which organizes the information and sends it to different areas of the cerebral cortex for neurological and conscious translation. The cerebral cortex is responsible for identifying the cause of the pain and comparing it to other types of pain, ultimately producing the sensation of pain. The signal is received by the thalamus to produce the corresponding emotional response, which may be anger, frustration, or crying.
This is the process of pain generation, but the spinal cord, as part of the central nervous system, can respond initially to external stimuli, for example, when a foot is kicked against the corner of a table, the foot is immediately removed in what we call a “reflex arc”, and this process often precedes pain. We need to understand that the part that produces pain is definitely the brain. The cerebral cortex has a memory for pain, which is one of the reasons why there is phantom limb pain.
How to quantify pain?
The International Pain Society defines pain as “unpleasant sensations and emotional feelings resulting from real or potential tissue damage”. Quantification of pain is very important and there are two systems that are widely used, the VAS scoring system and the NRS scoring system.
The VAS scoring system, also known as visual analogue pain scoring, uses illustrations to allow the patient to indicate the expression that most closely resembles a real response. the advantage of the VAS is that it is appropriate for every age group and does not require the patient to learn terminology and describe feelings.
Another more common one is the NRS (Numeric Pain Rating Scale). Doctors ask patients to rate their pain level out of 10, which represents the most extreme pain imaginable (e.g., childbirth), and a score of 0 means no pain at all.
But quantifying pain is not so simple, because everyone feels pain differently. Some people are naturally more pain tolerant, while others will exaggerate pain due to emotional impact or pessimism about the situation. We may also need a more reliable and detailed scale to assess pain. However, given the large number of different mechanisms and environmental factors involved in pain, this scale may never emerge.