EPThttp://www.teamliquid.net/blogs/viewblog.php?id=151543
Now one with the second part of my informational material. Part one focus on getting people who have never heard of breath hold diving some basic information, and really only covered the basics. In this blog i am going to be talking about the physiology of breath holding, and why the human body is so amazing. I am going to be explaining why holding your breath doesn't kill brain cells, and hopefully shed some light on the aquatic side of humans.
First some music for your enjoyment when you are reading
Now onto the content!
To start human beings are pretty amazing creatures! Holding your breath for 10 min plus is no small feet, yet the human body can do it, also descending to the bone crunching depths of 700ft can still come back perfectly fine, is no small task for our bodies. Many years ago it was a known fact that many marine mammals could hold their breath for extended periods of time, and dive to incredible depths.
This little guy right here is called a beaked whale, and it is the deepest diving mammal in the world.
Now while human may never be able to match dolphins, whales, or seals in the water- we do share some of the same adaptations. Surprisingly, a land creature that evolved from apes has the same type of physiologic responses when placed in water as dolphins, whales and seals do.
Cue the mammalian diving reflex. This is the most amazing thing that we, and all other sea mammals share. This allows for such incredibly long breath holds, and ability for humans to dive so deep with out imploding. Basically the mammalian diving reflex does a few very important things in human physiology.
When you, or your face is placed in water (preferably cold water) your body will go through a number of changes. The first primary change is bradycardia (or a slowing of the heart)Some divers when diving at depth, have a heart rate as slow as 30 beats per minuet! the reason why the heart slows down is quite simple: it is attempting to conserve as much oxygen as possible, the slower and more relaxed the heart- the better. Because a slow heart is a very effective one.
Secondly it causes massive peripheral vasoconstriction. (Or all of your blood vessels not in your core, and closed / or made much much smaller) This again is to help conserve oxygen, and it also pools your blood into your core. Another effect this causes is for your carotid arteries (the vessels that feed your brain) to enlarge and expand. This means that when you are holding your breath for a long period of time, your brain is in fact getting a more substantial amount of oxygen and nutrients from your blood stream.
The reason this is so is quite simple, your body does not want to hold it's breath. Because you can only live so long with out air, so your body wants to make sure that your brain can figure a way out of this mess, so it gives it the best chance possible.
On September 10 2010 08:58 Thats_The_Spirit wrote:
Cool, but also scary stuff in my opinion. It can't be good for your brain.
I'd like to see a study on long term effects where IQ/vision/memory/overal brainfunction are compared between a group of people who regurlary hold their breaths for 6 minutes and a control group.
I found an article published in 2008 in which they describe a considerable drop in PaO2 and a significant increase in serum levels of the brain damage marker S100B during extended periods of static apnea.
Quote: "It is not possible to conclude that the observed increase in S100B levels in serum after a maximal-duration apnea reflects a serious injury to the brain, although the results raise concerns considering negative long-term effects. At the least, the results indicate that prolonged, voluntary apnea affects the integrity of the central nervous system and do not preclude cumulative effects."
Cool, but also scary stuff in my opinion. It can't be good for your brain.
I'd like to see a study on long term effects where IQ/vision/memory/overal brainfunction are compared between a group of people who regurlary hold their breaths for 6 minutes and a control group.
I found an article published in 2008 in which they describe a considerable drop in PaO2 and a significant increase in serum levels of the brain damage marker S100B during extended periods of static apnea.
Quote: "It is not possible to conclude that the observed increase in S100B levels in serum after a maximal-duration apnea reflects a serious injury to the brain, although the results raise concerns considering negative long-term effects. At the least, the results indicate that prolonged, voluntary apnea affects the integrity of the central nervous system and do not preclude cumulative effects."
So i hate to say it, but no- holding your breath is not going to hurt your brain, at least because of a lack of oxygen.
Lastly the diving reflex also causes a blood shift. when divers are diving very very deep a very strange and necessary adaptation happens- your lungs and thoracic cavity fill with blood plasma. As a diver goes further and further under water, the pressure that is exerted on the body, and especially the lungs becomes ever greater.
In order to compensate for this huge pressure change (like your lungs shrinking to the size of base balls) the body can adapt in the most amazing way. Your thoracic cavity is filled with blood plasma, as well as the avioli in your lungs (those are the areas where oxygen transfer takes place in the lung) Because fluid is incompressible, the diver can descend further, instead of suffering a deadly lung trauma.
I don't want to bore you any more with all of that physiologic mumbo jumbo- but expect more next time in my other blog, about some free dive training, and some breath holding techniques. till then TL
For some evolutionary stuff
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Humans are quite a peculiar species. Having come from either chimps or gorillas from some common ancestor some 9million years ago- the fact that we have this reflex is testament to your earlier past as some how being a more aquatic ape. You see while all sea mammals share the diving reflex, not a single land creature has this adaptation that we know! we are it! Apes cannot swim, and because they are our closest ancestor- isn't that just facinating that somewhere in our past, the human being began spending so much time in the water that all of these changes began to take place?
Ohh evolution and science is so cool!
Ohh evolution and science is so cool!
edit: spelling
edit: fixed link
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