Posts Tagged With: parasympathetic nervous system

Why didn’t I go to medical school?


This is some of the thinking that contributed to the recently released Darwin’s Paradox: An international science mystery Novelists are always accused of adding biographical details, especially by their families. On their other hand they are advised to “write what you know.” The Ariq, a medical school dropout from Mongolia is a bit autobiographical. Yes, I have been to Mongolia.

I can’t stand the sight of needles or blood. When I go in for a blood test, I close my eyes and cringe. When it’s all over, I know it’s polite to assure the phlebotomist (that’s what they are called) that their technique was painless. I just can’t stand the idea of sticking a needle into me and drawing out my blood. When I get a vaccination, the nurses are concerned I might faint (more on that later). When I watch movies or television, I close my eyes and cover my face during any scenes with blood or needles.

I am not alone. About 3-4% of the population has something similar or even more severe. The condition is called: vasovagal syncope (sin-coe-pee), or neurally mediated syncope (NMS), or vasodepressor syncope, or even reflex syncope. Syncope is just the medical term for fainting. I don’t faint, because I follow the advice given to those who do: “don’t do that (whatever causes you to faint);” I don’t look at blood or needles. This condition is idiopathic, physician speak for: “I don’t know the cause.”

Medical Science might not know the cause of NMS, but that doesn’t mean nothing is known.

NMS has to do with the autonomic nervous system. That is the part of your nervous system responsible for automatic behaviors. You control what you put into your mouth, chew, and swallow, but once the food gets into your digestive tract, the autonomic nervous system takes over. Also, your autonomic nervous system keeps you breathing and your heart beating 24/7.

One part of the autonomic nervous system is the sympathetic nervous system which gets lots of press for its part in “fight or flight” responses. Vasovagal syncope is controlled/caused by the under-appreciated parasympatheic nervous system which controls “rest or digest” responses. That’s right! Fight-or-flight is not the only choice. One system prepares for action and the other for inaction. It is an over-reaction of the latter that causes fainting.

It is assumed that evolution has maintained this “rest or digest” response because it’s beneficial. Perhaps, if two people received severe traumas, the one who could lower their blood pressure had a better chance to survive by bleeding less and healing faster. Clearly, pumping the body full of adrenaline (fight-or-flight response) is not beneficial if you are bleeding profusely – in spite how often this is seen in action movies.

Here’s the movie scene I’d like to see. The hero and the antagonist wound each other. Now the antagonist gets mad, flexes her muscles, swinging her battle ax like crazy until she bleeds out over the passed-out body of our fainting hero. Evidently, that’s how my ancestors got this far and saying “not for the faint-hearted,” might not be true.

Also, the rest-or-digest response could work like a playing-dead response which is often beneficial when faced with an attacking animal.

So it seems that the meek have inherited 3-4% of the earth. Regardless, one way or another, my ancestors found a survival boost from their reaction to blood. I no longer need to be embarrassed. I have a name for my condition (actually four names) and assurance that I am not alone. I even can smugly know that many (genes) without reflex syncope did not make it this far. So there!


Categories: Diseases | Tags: , , , | Leave a comment

Create a free website or blog at