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Medical Reactions to cuts

  1. Jan 19, 2009 #1

    Mentallic

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    I went for my 2nd ever blood donation today. Last time I managed to only give 1/4 of what was expected, apparently my (right) arm was tensed too much and wouldn't allow blood to flow freely. This time we went to try the left arm.
    Well, the guy that inserted the needle did a poor job of it and missed the vein. The blood spurted out of my arm. Another more experienced assistant came to try my right arm and successfully inserted the needle. However, she also said that the blood wasn't flowing fast enough so we had to abort the procedure.

    I've never been good with cuts (while the sight of blood doesn't bother me). I regularly get that sinking feeling inside my stomache that makes me feel like I'm about to faint. I researched a bit on it and found that this is due to a lowered blood pressure in my body not being able to send enough blood to my brain. But why would I feel like fainting?
    Well, apparently I have a subconscious thought of fear and this lowers my blood pressure, causing me to nearly faint.

    What a pathetic natural reaction! When you're scared (possibly being preyed in the wild), there should be a pump of adrenaline running through the body to allow for survival, not a faint feeling. What good is it if the predator can simply scare its prey to death? Why do so many people feel faint after giving blood or taking a needle?
     
  2. jcsd
  3. Jan 19, 2009 #2
    Predators rarely look like giant needles. If the sight of your own blood doesn't bother you, more then likely its the needle.
     
  4. Jan 19, 2009 #3

    Monique

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    Many animals play dead in order to survive a predator attack.
    It is called a vasovagal response: a reflex of the involuntary nervous system that can lead to loss of consciousness.

    This is an interesting publication: Vasovagal syncope and Darwinian fitness
     
  5. Jan 19, 2009 #4

    berkeman

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  6. Jan 19, 2009 #5

    Mentallic

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    It has happened to me from certain cuts too.

    If I had a choice to either be conscious or unconscious when playing dead to try avoid predators, I would rather stay conscious to at least have the chance of trying to run if the predator decides to play with its food.

    wow this is truely interesting! Perfect sense to explain an imperfect reaction.
     
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