The Body, Simply

Ouch!

Kevin's head was throbbing with pain. To him, headaches were just bad, but waking up with one in the middle of the night was definitely the worst.

"Should I get up and take some aspirin?" Kevin asked himself in the darkness.

His unwillingness to leave his warm bed said, "No."

At first, Kevin listened to the voice of his laziness, assuming that falling asleep would be as fast and easy as... well, falling asleep. But after several minutes, he realized it was impossible to do so with this nagging headache.

"Maybe I should get up and take some aspirin," he told himself, and awaited no answer this time.

With a sigh, Kevin rose to his feet. He picked up his mobile phone from the table next to him, and used its flashlight to make it safely to that near drawer. He was sure he left a strip of aspirin pills there. And he was right: there lay the savior of a good night's sleep.

He took a pill and pressed it against his lips, but as his mouth opened he remembered that he needed water to swallow it. That meant that he had to go to the kitchen downstairs. He sighed again, and with the mobile phone still in his hand, he left the room and did what he had to do. After some more minutes, he would finally be able to sleep. But on his way back upstairs, he heard a giggle emanating somewhere in the darkness.

Kevin turned round with a jolt, scanning his surroundings with the light of his mobile phone. There was no one, and there wasn't supposed to be anyone, as Kevin lived alone. So of course he must have imagined what he'd heard. Surely it was all in his head.

"You're tired and imagining things," he muttered to himself, climbing the staircase in determined steps. "Now go and get some sleep and stop imag—"

A sharp pain went up his leg spread through his whole body, causing his eyes to water and his body to go stiff, as if paralyzed. A scream of agony escaped his mouth, and it took his body a moment or two to break free from the invisible chains binding it. The hand holding the mobile phone was the first limb to regain movement.

He looked down near his feet, and in the flashlight, he saw what he stepped on and caused this torture. A lego. And before Kevin could comprehend anything else, he heard someone giggle again, but this time it was right behind him.

***

Poor Kevin. He would have spared himself so much trouble if he'd turned on more lights, don't you think? Anyway, hello and welcome again. Today we will talk about pain, and we will use our friend Kevin's little story to demonstrate some stuff. Let's begin.

First of all, pain is an unpleasant sensation caused by damaging stimuli. It's your body's (annoying) way of telling you that something is wrong, and it keeps telling you that over and over and over again, because it wants to protect itself by urging you to remove the damaging stimulus or to get away from it.

There are different types of pain, and according to the site of its origin, it has three types. Cutaneous pain is the type that arises from the skin. Deep pain arises from deep structures such as muscles or joints, and an example for it would be the pain of bone fractures. The third type is visceral pain, which the pain originating from your internal organs. But how exactly does pain occur?

Pain (and all sensations in general), starts at the stimulation of its specific receptors. And when it comes to pain receptors, they can be stimulated by mechanical, thermal or chemical stimuli provided that they cause tissue damage.

And it's this tissue damage itself that actually causes the stimulation of pain receptors. When a tissue is damaged, it leads to the release of certain pain-producing chemicals, such as prostaglandins, and these chemicals lead to the stimulation of pain receptors. And once these receptors are stimulated, the sensation, in the form of a signal, will travel up your spinal cord until it reaches your brain, where the pain is finally perceived. After that the brain responds by sending down signals that will lead to reactions that differ according to the type, site and intensity of the pain. This is a very concise way of putting it, because we don't want to delve into the details of neuroanatomy. Not today.