Have you ever experienced riding in a car under the low-hanging branches of a tree and then lowering your head quickly to avoid the boughs in spite of being safe inside the car? It happened to me countless times and I'm sure many have gone through this rather embarrassing scenario, too. Coming to our wits, we realized at once that there was really nothing so abashing about it. The reaction was a result of one of our body's natural reflex mechanisms coming to work.
Because of these reflex mechanisms, many injuries are prevented. Consider these other examples on how our body's automatic reflexes protect us from certain harm: When an insect threatens to enter a person's eye, he automatically blinks his eyelids. A person watching a ball game from the bleachers dodges instinctively when an errant ball flies too close to his head.
Reflex mechanisms are also at work even in the process of swallowing food or liquid. What happens during this simple process is that the whole voice box is raised in order that the entrance to the voice box is shut as food or liquid passes through the esophagus. Air is simultaneously carried into the windpipe and lungs by the opening through the voice box. If not for the reflex mechanism that shuts this air passage, stray food would find its way into the air passages. With the reflex mechanisms functioning perfectly, only food and liquid are allowed to pass through the esophagus, while only air goes into the windpipe.
In the event the usual reflex mechanism for preventing food and liquid from entering the windpipe malfunctions, a second reflex mechanism goes into work. This standby mechanism forces coughing and choking in case stray food gets into the windpipe or voice box. Consequently, air is forced out of the lungs instantly that it brings the stray food along with it.
The human body has been designed to confront unforeseen circumstances that might threaten its healthy state. For example, besides its ability to make its own repairs, such as healing bruises, mending lacerations, or even restoring broken bones to their normal state, the human body is likewise able to ward off in advance many injuries caused by accidents and diseases. Unfortunately, this is something we usually take for granted until the next baseball that goes awry passes several inches off our head, or a menacing fly attempts to enter our eye. Credit must go largely to the different reflex mechanisms of the human body.