Erin is the second winner of our science writing competition, and entered the 13-15 year old category. She is 14 years old and her home country the UK. I really enjoyed Erin’s piece about reflexes, it is well written and explained everyday science perfectly. Again, very impressive for someone so young; Congratulations Erin. The following is entirely Erin’s work, enjoy…
Granddad’s Superhero Reflexes or Science?
Recently, I was in the kitchen helping my granddad with some cooking when he accidentally touched the hot pan. Amongst other actions, my granddad was able to pull his hand away from the pan and move to the kitchen sink with speed that I’ve only ever witnessed when Usain Bolt beat the 100m world record. To say the least, I was confused; how could my granddad have done this so fast?
After some head scratching and confusion, I found out the science behind it which, of course, made the whole situation seem much less like the work of a magician and more like an example of how science benefits us in day-to-day situations. It was a reflex.
A reflex is an involuntary and immediate action issued in response to a stimulus (a change in the environment). In my granddad’s case, the stimulus was the change in the temperature of his hand after touching the hot pan. This was potentially dangerous, as poor granddad could have had serious burns if science not gifted him with speedy reflexes (what a relief).
To my poor granddad’s confusion, I found the science behind what he had just experienced to be very interesting indeed. The reflex arc had intervened to save his hot hand, and just in the nick of time! A stimulus was identified by the receptors on the skin of granddad’s hand. Then, an electrical impulse is sent along the sensory neuron into the central nervous system (CNS), which is the spinal cord. Here, something very cool happens; the electrical impulse must transfer from the sensory neuron to the relay neuron even though the two do not touch. There is a synapse; in other words, a space between the neurons. The sensory neuron releases chemicals which are recognised by the receptors on the relay neuron. The relay neuron then generates an electrical impulse which is sent along it to another synapse, where the relay neuron releases chemicals which are recognised by the receptors on the motor neuron. Leaving the CNS now, the electrical impulse travels along the motor neuron to the effector: a muscle or group of muscles which make the muscles contract to issue a response to the stimulus. This made my granddad’s hand move away from the hot pan. Phew!
Reflexes are involuntary actions; they take part without the conscious part of the brain, which is why they are so fast. There are many examples of the reflex arc in use, for example: squinting in bright light, digestion and so on. There are many other examples as there are many receptors in the body and the effector may also be a gland as well as a muscle.
So, 5 minutes after my granddad accidentally touched the hot pan and I’d done a quick Google search on what had actually happened, my granddad and I sat down to tea, satisfied that the wonderful world of science had answered my question.