Pain is the body's warning system, alerting you that something is wrong. The International Association for the Study of Pain defines it as an unpleasant experience associated with actual or potential tissue damage to a person's body. These cells respond to things such as injury or tissue damage. For example, when a harmful agent such as a sharp knife comes in contact with your skin, chemical signals travel from neurons in the skin through nerves in the spinal cord to your brain, where they are interpreted as pain.
Acute pain is temporary.
It can last a few seconds or longer but wanes as healing occurs. Some examples of things that cause acute pain include burns, cuts, and fractures. Chronic pain, such as that seen in people with osteoarthritis and rheumatoid arthritis, ranges from mild to severe and can last a lifetime.