Lasting Effects of Pain :: Biology Essays Research Papers

Lasting Effects of Pain INTRODUCTION Once upon a typical sunny day, Mary, Susie, and Jackie are jumping rope. Unbeknownst to them, as they chant their rhymes, Mikey and Kenny hide in the bushes planning a surprise attack. Just as Mary's little feet barely lift off the ground, the two boys leap towards the girls and push them into the dirt. "Ouch!!!" they all scream as everyone hits the dirt. Mary is up on her feet with her knees skinned and bleeding. A smile slowly crept on her face as she tried to hold back a chuckle. "What's so funny?" asked Mikey, as everyone turned to look at her. "Aren't you supposed to get mad and chase us around?" Mary shrugs and looks down at her knees. "Doesn't that hurt?" asks Jackie. So what exactly does Mary feel when she hurts her knees? Pain, of course. But, how exactly does she experience it? Well, inside Mary's tissues lie nociceptors. Nociceptors are specialized sensory nerves that are activated when there is a potential for danger, such as Mary falling to the ground. The stimulation of nociceptors, first, allows large-diameter, myelinated axons to carry rapidly conducted action potentials. This causes the sensation of a sharp, well-localized, pricking or cutting pain. It is then followed by a diffuse burning or aching pain caused by more slowly propagated action potentials that are carried by smaller, less heavily myelinated axons (1). The action potentials are generated and conveyed to the central nervous system by way of a difference in electrical potential (2). When the threshold potential difference for each nocicpetor is reached, a signal is sent to the central nervous system. As the signal continues to travel to the spinal cord, the medulla, the thalamus, and then the cerebral cortex, it must pass through a series of gates (3). According to the gate theory of pain, the awareness of pain can only get to the brain by passing through a series of gates (Melzack and Hall, 1965). To open a gate, a group of small neurons that form a "pain pool" must reach their threshold. When it is reached, the signal is allowed to be sent higher. So as Mary and everyone else who falls to the ground, their body is undergoing this awareness of pain. Kenny is next to stand up. "Owww, there's sand in my leg," he whimpered unhappily. "Hey, you pushed us, and now you're crying?