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RecycleJack Marine's picture

Reflex and Reaction

I just had a reaction that sent chemicals into my brain and created a brief period of depression, after I accidentally deleted my blog entry. It's gone! But I am happy to say that the chemical reaction is dissipating and I am feeling better. Maybe I needed this to put PHYSIOLOGY into perspective!

Peter told us about Dive Reflex and it cleared up what I've always wondered how reptiles and some amphibians stay submerged under soil or mud for the winter months. In humans, the Dive Reflex allows mostly younger humans to stay alive when floating in freezing water. The body only uses oxygen in the blood to pump to the heart and brain, so we don't have to breathe as much as we would normally.

What is the difference between reflex and reaction:

Many people conider only the simplest types of responses as "reflexes", those that are always identical and do not allow conscious actions. We must not confuse these with "reactions", which are different from reflexes in that they are voluntary responses to a stimulus from the environment. For example, while the body has various subconscious physiological responses to mitigate cold, as humans we can simply choose to put on more clothes. This is a conscious order made by the cerebrum, not an involuntary response to a stimulus. This is a very complex response involving millions of neurons and some time to process the voluntary response. In contrast, spinal reflexes occur much faster, not only because they involve fewer neurons, but also becuase the electrical signal does not have to travel to the brain and back. Spinal reflexes only travel to the spinal cord and back which is a much shorter distance. Because of this and the complexity of conscious reactions, they take more time to complete than a reflex. On average, humans have a reaction time of 0.25 seconds to a visual stimulus, 0.17 for an audio stimulus, and 0.15 seconds for a touch stimulus (2). Reaction times vary from individual to individual. Because of the higher degree of neural processing, reaction times can be influenced by a variety of factors. Reaction times can decrease with practice, as often times athletes have faster reaction times than non-athletes. Sleepiness, emotional distress, or consumption of alcohol can also impact reaction time.


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