The Physiology of Pain: Here's What Happens in the Body When One Experiences Painful Sensations

People may experience pain when signals move through nerve fibers all the way to the brain for interpretation. Feelings of pain typically result from tissue damage and enable the body to respond to and prevent or avoid further harm.

The Physiology of Pain

Sensations of pain are typically felt when certain nerves, known as nociceptors, pick up tissue damage and relay information regarding this damage. The information is sent through the spinal cord all the way to the brain.

For instance, when a person touches a hot surface, a message will be sent through a reflex arc within the spinal cord. The action itself will also immediately lead to muscle contractions. Such contractions will make the hand distance itself from the surface in order to limit more impact and damage.

Such a reflex happens even before the message arrives at the brain. When the relayed information does arrive, it makes the person feel the unpleasant sensation of pain.

How the brain interprets the signals and how efficient the nociceptor-brain communication channel is could affect how a person experiences pain.

In order to counter the unwanted effects of pain, the brain may also end up releasing chemicals for feeling good, such as dopamine.

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Types of Pain

Pain comes in different types, which is markedly determined by its duration. Pain could either be acute or chronic in nature. Acute pain is generally short-lived and intense, while chronic pain persists longer and typically does not have any cure.

Acute Pain

Acute pain is how the body informs a person regarding any localized tissue damage or injury. In most cases, treating the injury could relieve acute pain.

This type of pain also enables the fight-or-flight response of the body and typically leads to increased breathing rates and heartbeats.

Acute pain can either be somatic, visceral, or referred. Somatic pain refers to superficial pain felt on the skin or on the soft tissues under the skin. On the other hand, visceral pain starts from the body's internal organs and cavity linings. Lastly, referred pain refers to when a person feels pain at an area other than the actual tissue damage source. An example of referred pain is when a person experiencing a heart attack may feel pain in the shoulders.

Chronic Pain

Unlike acute pain, chronic pain lasts longer and typically does not have any cure. It can either be severe, mild, intermittent, or continuous. Intermittent pain repeatedly occurs with interval stops between episodes or flares.

For people who experience chronic pain, the fight-or-flight response eventually stops. This is because the sympathetic nervous system, which is responsible for triggering such reactions, ends up adapting to the pain stimulus.

When sufficient acute pain cases take place, they could lead to an electrical signal buildup within the central nervous system that ends up overstimulating nerve fibers. Such an effect is known as a windup. It is similar to a winding toy that can run faster for longer periods when it has more intensity.