I really don’t understand the brain

4 April 2005 at 14:03 (General)

Something I found out today that I thought was amazing:

When you are exercising your muscles need more oxygen/carbon dioxide exchange so they get an increase in blood flow to facilitate this increased exchange. However, according to my text book (Human Physiology, Sherwood, 2004), no matter what you are doing your brain receives the same amount of blood. If you are thinking, exercising, sleeping (i wonder if you are in a coma?) your brain always receives ~650ml of blood every minute. HOWEVER, the distribution of this blood within the brain alters depending on what you’re doing. That’s why, when they do a PET scan (one of those medical things that produces the brain image with typically a black background and a coloured rainbow plot showing where the activity is) different parts light up different colours. They are actually showing a scale of the blood flow to different part os the brain.

But I would think that if your frontal lobes (up the front) are needing lots of blood because you are thinking intensely, it would limit the amount that you’re cerebellum (out back) would receive so your seeing wouldn’t be as fast or refined. However, in my experience, it is all able to happen seamlessly at once. I’m sitting here looking at the text as I type, listening to Sonic Animation, worrying about the assignment I’m still not doing while composing a blog entry. So, I would assume all of these parts of my brain would be cranking along, but they can’t all be, they are still only receiving the same amount of blood they would be if I was asleep.

This affirms why asphyxiated induced fainting/orgasm is a stupid thing to do. Seems like riding a bike with a flat tire, it’s not the way we’re designed to operate.

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4 Comments

  1. Kent said,

    This explains why you rode into that car up by the tennis courts. Remember what you were doing at the time?

  2. toto said,

    Yeah, maybe I was looking where I was going, my brain just couldn’t afford to decode the impulses it was receiving from my eyes.

  3. Kent said,

    No duh, you were talking to me. There was obviously a lack of blood flowing to the ‘hmm what would be a good message to send to my arm muscles’ department (especially its ‘good sense’ liaison officer)

  4. Deirdre said,

    I’m amazed there’s 650ml blood per minute. That seems like a lot. It’s not something I’ve ever thought about – we’ve got highways rushing through us all the time, blood coursing around non-stop. It seems tiring. Maybe it is. Maybe that’s a good excuse: I need to rest, my blood’s been racing particularly fast today.

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