Pain can be a warning that your body is injured or infected. The doubled-over pain of a ruptured appendix will send you straight to the emergency room; without this warning, you would die. This type of acute pain usually lasts until your injury or infection heals. But not all pain serves a purpose. Pain that lasts long beyond the normal recovery period, such as lower back pain or migraine headache, is called chronic pain, says the American Pain Society. Disabling chronic pain—the type of pain that keeps you from working and enjoying life—should be treated.

In terms of numbers of pain receptors, two parts of your anatomy may tie for most sensitive. One is the mouth—think of spicy food that burns your tongue, cold ice cream that sends painful shivers through your teeth, or a throbbing molar, and you get the idea. The other body part is the genitalia.

It’s your brain, not your earlobes, that is least sensitive to pain. Your brain can process pain messages, but it has no pain receptors of its own, says the National Headache Foundation.

Certain otherwise normal people are born incapable of feeling pain. And while you might think living without pain sounds like a good deal, it’s really not. Pain is really protective; if you don’t have that, you die, because you can’t take care of yourself.

Pain is an emotional experience. Doctors can get physical responses—including increased blood pressure and heart rate—by trying to stimulate coma patients pain receptors. But without the brain working to register and comprehend the pain, it’s unlikely they feel anything.

Everybody gets a simple headache now and then. The National Headache Foundation lists 21 common types of headache that affect more than 45 million Americans annually.

About 70 percent of migraine sufferers are women. Migraine headaches cause a severe throbbing pain on one side of the head, often accompanied by nausea, vomiting, or dizziness. About 28 million Americans suffer from migraines. Women seem to suffer migraines more often because fluctuating hormone levels cause contractions in the blood vessels in the scalp.

It depends on the person, not the person’s gender. Some people have a higher level of natural pain blockers, such as endorphins and serotonin, that act the same way that narcotics do by stopping pain messages from traveling to the brain. What may feel like agony to you might be perceived as mild discomfort by your next-door neighbor, all thanks to these self-narcotics.

The phenomenon of pain is a perception. Your brain can, in effect, amplify the pain experience or turn it down to a whisper. This is how yogis can stick needles into themselves or walk on a bed of hot coals. With sustained concentration, they are able to override the discomfort.

But there was a time when doctors believed babies were unable to feel pain and even operated on them without anesthesia. That view has changed; there is no question that newborns can feel pain and respond to it.

A heart attack, for example, can manifest itself as pain in the left arm. Or tooth pain can be felt as an earache. This is known as referred pain.