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Mammalian Diving Reflex just a Romanticism?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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fpernett

fpernett

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Nov 7, 2001
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This is the summary of an article published in the last issue of the JAP. I think is interesting for us:
Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans
Johan P. A. Andersson,1 Mats H. Linér,2 Anne Fredsted,1 and Erika K. A. Schagatay3
1Department of Cell and Organism Biology, Lund University, SE-223 62 Lund; 2Department of Anesthesiology and Intensive Care, Lund University Hospital, SE-221 85 Lund; and 3Department of Natural and Environmental Sciences, Mid Sweden University, SE-851 70 Sundsvall, Sweden

Submitted 18 November 2002 ; accepted in final form 21 October 2003


The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10°C) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.

diving reflex; bradycardia; vasoconstriction; oxygen and carbon dioxide stores; breath holding



--------------------------------------------------------------------------------

Address for reprint requests and other correspondence: J. P. A. Andersson, Dept. of Cell and Organism Biology, Lund Univ., Helgonav. 3 B, SE-223 62 Lund, Sweden (E-mail: [email protected]).
 
donmoore

donmoore

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Frank,
Great article and study! This about sums it up. The body responds to apnea by conserving O2, but the conservation is even greater when the face is submerged. Non-depth pressure Mammalian Reflex!
don
 
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fpernett

fpernett

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Nov 7, 2001
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Yes Don,
If you want to read it all, PM and I'll send it to you
 
tylerz

tylerz

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Jun 19, 2002
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If I am reading the article correctly, it is stating there is a difference of 3% between the oxygen consuming effect of apnea alone and apnea in water. This means that 92% of the effect is due to non-aqautic reflex and 8% is due to aquatic.

If you regard my original questions and statements in creating this thread then, does this not support the whole point of the thread? I stated from the beginning that the water most likely has a play in the equation but is a supplement to a more dominant effect caused by pure apnea. The thread did not try to suggest there is no diving reflex. Therefore in communicating the concepts of diving reflex and apnea, everything seems to be pointing at the idea that we should put more emphasis on the main players in the equations to provide a more accurate idea of the reflexes involved in apnea/diving.

Cheers,

Tyler
 
donmoore

donmoore

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Tyler,
I don’t think Frank or I was trying to disprove your statement. Your thoughts about concentrating on the main players in the O2 conservation adaptation is a good one for making the thread. It’s really nice to see some quantifying evidence on just how much of the Mammalian Dive Reflex can be contributable to facial submersion. The significance to this for me is that one should be able to at least duplicate their dry static times. If their wet statics are not at least equal, then they need to look at what factors are different and see if they can modify those things to put themselves in a state that is more like their dry statics. This is important to me, because I passed out in a wet static in a time, much less than I was doing dry in the preceding days to the wet.

I’m not sure about the 3% improvement. If it is only 3% then that would be an additional 13 seconds at 7 minutes. They talk about Oxygen uptake from the lungs decreasing by less. That seems a little weird. Seems like all that is saying is the body is drawing less O2 out of the lungs, which could mean its using less, but is not a very direct measurement. Seems like a more direct measurement would be blood O2 concentration.

Frank, please go ahead and PM me the whole article.
Thanks,
don
 
tylerz

tylerz

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Jun 19, 2002
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Great article and study! This about sums it up.

Great, just trying to clear up the ambiguity that could be drawn from the posts. I could not agree more with the value of information, such as this, that we can use to troubleshoot and learn from in this amazing activity and any others.

Cheers
 
fpernett

fpernett

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Nov 7, 2001
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Hi Tyler,
I agree with Don, nobody has the whole truth, we all are looking for it.
I found some interesting data in that article:
The PetO2 (end tidal oxygen pressure) after apneas in air was 50 +/- 1 and after apneas in face immersion (cold water) 53 +/- 1 (p<0.001)
The PetCO2 after apneas in air 62 +/- 1 and with face immersion 61 +/- 1 (p<0.001)
RER (respiratory exchange ratio) for apneas in air 0.52+/-0.01 and face immersion 0.53+/-0.01, p< 0.001
(Normal RER is 0.8 in rest and 1.0 in exercise)

"The diving response will in this way afect the utilization of lung and tissue O2 stores during apneas, and the lung O2 store will be preserved at the expense of the venous O2 stores".

My English is not perfect, so forgive if I not make my self clear.

This experiment wasn't perfect, and they was evaluating the apnea response while exercising (air and face immersed). Nobody was at the limit of his apnea, so the results at the end of a extremely long apnea could be different.
What is clear is that we have a response to apnea that gets deeper with face immersion in cold water.
The Tyler question is good, but difficult to get answered; how do you know that this response was not associated to diving in our ancient relatives. I don't know if somebody remember Pavlov's experiment:
He always feed a dog in the same way: ring a bell, opened the door, serve the food and gave it to the dog, and the salivation of the dog was associated to the food. After some time with only the sound of the bell the dogs started the salivation, if we translated to apnea the bell could be the breath-holding and the salivation the diving reflex. Mainly if we take into account that the majority of our ancestor only held their breath for diving.
Did I explain it well, or better go for English class?. ;)
 
tylerz

tylerz

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Jun 19, 2002
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Just to follow up on this thread...

At the recent AIDA Worlds Freediving Championship, there were talks held by scientists who have been studying various aspects relevant to freediving. One such speaker was associated with the SFU studies that Kirk Krack assists in.

It was interesting to note that during his powerpoint presentation he emphasized with two screen pages, exactly what I initiated this thread with.

To quote what can be seen on the videos:

Dynamic cardiovascular responses during Breath-Hold
by
Andrew P. Blaber, Ph.D.
School of Kinesiology
Simon Fraser University
Burnaby B.C. Canada

So, what I am going discuss today is the responses to apnea because what we think is that [the response to apnea] predominantly is driven by the effect of the hypoxia and hypercapnia on the receptors in the body. Cold stimulus and facial immersion, add to that but the majority of the effect is basically apnea response because of the sensitivity to carbon dioxide and low oxygen.
 
donmoore

donmoore

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Tyler,
Good to see you posting again. I have been experimenting with how different mental attitudes effect performance, which I also think translates Bradycardia and Vasoconstriction. I would almost venture to say that part of the effect of facial immersion actually comes from the state of mind it helps put a person into.

I remember you mentioned that you have tried to invoke vasoconstriction by mentally focusing on it. I have been reading this phd’s book (Dr. David Wise) which is on a subject quite different than freediving, but still important to me, because it relates to a medical problem I have. He focuses a lot on total relaxation and refers to several scientific studies on relaxation to obtain dos and don’ts of total relaxation. One don’t is don’t think of words. When the mind thinks in words the vocal cords actually tension and move some. Instead think on things like body sensations and non-word things like soft slow music. To me thinking of the word constrict, “in constrict blood vessels”, would tense me.

I am convinced that thoughts play a huge role in O2 conservations. I haven’t been pushing my static times to the limit lately, but with my Oxy/pulse meter I have been recording the highest O2%, at the set intervals I make it to, ever.

Thanks for your update on the thread with the message of the speaker at the Worlds.
don
 
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tylerz

tylerz

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Jun 19, 2002
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Hey Don,

I also anticipated that conclusion regarding thinking in terms of words. Words are translations of concepts in our mind, therefore it takes time and energy to perform these translations, even if it happens extremely fast. Just for the pure fact that it is a second level of redundancy, implies that it is wasting energy. How much energy? Well I suppose that depends on the efficiency of the person, but most likely it is significant for the average person. Even without words energy can be wasted in the mind if you find yourself following a "train of thought". This implies your brain is actively solving a problem and therefore working quite hard. So, I think at the simplest level, we should be looking to not focus on any words or even concepts that touch our awareness. Awareness I think is fine, but not focus.

Anyhow, good to hear from you. How are the holds coming?

Cheers,

Tyler
 
W

wet

Freediver82 - water borne
May 27, 2005
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I saw this interesting thread, thought I’d add some responses to selected messages, some may be out-of-date.
Sebastian: The reflex is there but why? With some grievance I must admit that I believe that its mostly romanticism.
The responses we get from holding our breath, holding our breath in water and holding our breath at depth (three different reactions)– I would say are mostly a shock reaction to what is happening at that very instance not because of some trait in our biology that is half aquatic (as Paul Kotik described with what would happen to a mechanic model in a similar situation). It takes great many years to adept to environment – and once we might have been those seaside monkies – but all those (most?) traits I believe have worked its way out of our systems. It would have been “Darwinian stupidness” to keep them – better to adapt fully to land where we have spent hundreds of thousands of years. Our mammalian diving reflex might not be a memory from a distant past in our biology – it might just be signs of two things:
1) Our bodys adaptation to live 9 months in water during pregnancy.
2) Our bodys just trying to survive (in fear of death).

The diving reflex I believe is more a SHOCK REACTION (in a body that believes it might be die-ing very soon). Cebaztian

ME: Sebastian mentions that divers reflex may be similar to process of birth of baby:
Platypus is a mammal, but not placental (live birth or eutherian), it is a monotreme (egg birth) it is hatched from an egg, like a turtle. Marine turtles’ ancestors were apparently freshwater-land turtles long ago.
I think both platypus and marine turtle have some kind of divers reflex, at least bradycardia.
Platypus, unlike seals & dolphins, doesn’t have anticipatory tachycardia (fast heartbeat) while ascending before surfacing.
I don’t know if Sebastian has changed his thinking about this, but I think SHOCK is more similar to tachycardia (as Frank said) or Fight or Flight reaction. I think the divers reflex is simply the method by which ancient humans gathered foods in the water, allowing gradual foraging at a slow pace, like deer munching leaves or apes plucking fruits or manatees eating seagrass. (This is completely different than aggressive hunting like a tiger or wolf chasing down prey). Our Mighty Hunter status came later...

Tyler Z.: … many of them have done dry statics, but few of them continue to do them regularly to the point that they are just as comfortable doing wet and dry. I have to ensure I have a low temperature in the room, wear no clothes on my upper body, support my knees with cushioning, and prop my head, for best results when doing dry statics.

Me: I am curious, in a (deep) dive, ½ the time the face is below the body (descent), ½ the time face is above (ascent). In a dry static, is the body and head position constant? Has anyone tried a dry static doing it ½ face way down (headstand), then ½ face way up (ie standing)? [Maybe dangerous!] I’m asking, because, seems to me, if a dry static is while head is above heart, then it simulates only the ascent. Maybe ½ time horizontal and ½ time vertical would work?

Tyler Z: another study demonstrated, if the subjects were pestered while doing apnea in water, the bradycardia and vasoconstriction did not occur. I think this supports the idea that they are very dependent on relaxation. Therefore it makes sense that the average person doing dry statics, not being relaxed, is not going to have the same response as floating weightless and cool in water.

Me: Yes, it seems like relaxation during apnea is important to divers reflex, while possibly being harassed or spooked (shark) or (IMO ascending into bright sunlight and/or warmth) near surface can activate tachycardia (faster heart rate).

http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract
Tyler Z: A quote from this link: "We conclude that bradycardia and hypertension during apnea are associated with a significant temporary O(2) conservation and that respiratory arrest, rather than the associated hypoxia, is essential for these responses."
This also seems to favor (or support) the idea of apnea being the strongest cause of oxygen-conserving responses (bradycardia and vasoconstriction), as opposed to water/diving.

Frank showed this paper: Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans
“Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas”.

Me: So apnea mostly causes the response, while facial immersion augments it. Seems to me the only position where this would have been beneficial to humans was while deep-wading & dipping face, or underwater swimming or deep diving during foraging.

Tyler Z: Dynamic cardiovascular responses during Breath-Hold by Andrew P. Blaber, Ph.D. School of Kinesiology Canada
“…what we think is that [the response to apnea] predominantly is driven by the effect of the hypoxia and hypercapnia on the receptors in the body. Cold stimulus and facial immersion, add to that but the majority of the effect is basically apnea response because of the sensitivity to carbon dioxide and low oxygen”.

Me: Interesting, I think it’s strongly augmented by temperature differentiation and pressure differentiation, but will review.

Don: …To me thinking of the word constrict, “in constrict blood vessels”, would tense me. I am convinced that thoughts play a huge role in O2 conservation...

Me: Also interesting, I’d felt the same. Now, I see it as a change from a terrestrial limbic (manual drive) pace to an unhurried glide, letting the autonomic nervous system (automatic) do the work, for eg. the truncal-axial musculature & thoracic contractions propel (“swording”) or Lungfish’s eel-like insinuations or a dolphin stroke. So rather than seeing vasoconstriction as tensing, I see it as filling the central tube, where it can be used to best effect.

Asides: In a book I read by Temple Grandin, an autistic author, she mentions many times about pressure being important (squeezing), it reminded me of diving, but I don’t think she mentioned diving explicitly.

During fainting, to revive, it’s suggested to put head down on chest and blow on or fan the face.
I’ve read in DB that part of relieving a shallow water blackout laryngospasm is to blow on the face at the surface.
I’ve also read in a baby-swimming text that the parent should blow on the baby’s face to indicate to breathe after surfacing.
Just some thoughts. DDeden
 
pkotik

pkotik

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I'm still interested in trying to build an idealized model of the human cardiovascular system that exhibits some of the dive reflex responses to ambient pressure and virtual apnea without any superimposed control system - no virtual nervous system, no endocrines, just a closed physical system. It would be interesting to discover the lowest level of simplicity which would still exhibit the divel reflex.

As for mainline AAH - I'm always thinking back to my wonderful lunch with Elaine Morgan in London, 2003. She offhandedly remarked that she was thinking a lot about the gasp response. Human beings, when startled, gasp: they suck in their breath and hold it. Very useful, she thought, in a world where surprises often result in a little underwater time.
 
W

wet

Freediver82 - water borne
May 27, 2005
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[From Paul's earlier post]
For example, as simple electric water pump driving water through a network of flexible tubes. The pump piston drive, let's say, by a belt drive that allows for slippage when the resistance encountered by the piston increases.

It would be interesting to see what would happen if we got this little system happily pumping away, then grdually submerged it to increasing depth. I think that we would observe a) a tendencey for the tubes most distant form the pump to constrict and collapse before those closest to the pump, and b) a reduction in the number of the piston's strokes per minute, as the belt begins to slip.

In other words, perhaps bradycardia and blood shunt are 'dumb' consequences of a physical system rather than 'smart' or adaptive responses of a homeostatic, physiological system.

pkotik said:
I'm still interested in trying to build an idealized model of the human cardiovascular system that exhibits some of the dive reflex responses to ambient pressure and virtual apnea without any superimposed control system - no virtual nervous system, no endocrines, just a closed physical system. It would be interesting to discover the lowest level of simplicity which would still exhibit the divel reflex.

As for mainline AAH - I'm always thinking back to my wonderful lunch with Elaine Morgan in London, 2003. She offhandedly remarked that she was thinking a lot about the gasp response. Human beings, when startled, gasp: they suck in their breath and hold it. Very useful, she thought, in a world where surprises often result in a little underwater time.

For some reason, when trying to imagine this pump, I kept seeing a submarine in my mind! Then, a water balloon 1/2 full of air, getting squeezed somehow.
The pump is hard to visualize for some reason. I have a question, what causes the further tubes to constrict? Since they are full of water, surrounded by water, I guess it's just the rate of the pumping pressuring the tubes beyond the ambient water pressure, so if the pump slows, the furthest tubes won't collapse but just be normal size. But if the pump is suctioning, the nearest tubes might constrict first? Sounds like it's too complicated for me.

I've talked with Elaine about the startle-gasp response, after having read your article in Deeper Blue. I tried to find something further on it, but found only information on hypoxia-induced gasping in vertebrates. I guess it's always accompanied by tachycardia (faster heartrate). I assume it's a fight or flight response, seems identical whether triggered by sudden startlement or sudden large temperature (hot or cold) change, but not by general pressure change, nor by olfactory (smell), gustatory (taste), aural (hearing), visual (sight) sensation.
Seems likely that the prickly feeling on the nape of the neck, often preceding a gasp from sudden fear or cold, is part of it, very handy while wading through water with waves. DDeden
 
laminar

laminar

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Aug 13, 2001
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Hi guys,

Neat discussion!

Wouldn't there not be a pressure gradient between the cappilaries at skin level and the heart? I don't remember how fluid in a complex system like a human body transmits pressure. If there was a gradient of pressure, and I would think there would be, then it becomes more and more difficult for the heart to get new blood to the extremities. So blood backs up. But then the heart has a smaller volume of blood to reoxygenate and circulate, so it can reduce its contraction rate and stroke volume. No?

If it is purely a mechanical phenomenon, how do we explain divers who get extremely shifted on their first dive vs. divers who need many dives to have it happen.

I'm more on the side that it is physiological and that it happens to everyone, but I still don't have an explanation for the variation in "dive response", unless it's just that experienced divers know the best way to stimulate that response from the beginning. Or that somehow the body gets used to the process after many years of being subjected to it and makes some adjustments to let it happen more easily?

:duh

Pete


Pete
 
laminar

laminar

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Aug 13, 2001
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However, if you exhale and lie on the bottom at 10m or even 2m without a suit in cold water until you get a contraction, this response will be much stronger. So its primarily physiological, by nature. Seb Murat would probably add that psychological and emotional states can also influence the cardiovascular response and deepen this shift.
 
tylerz

tylerz

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Jun 19, 2002
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laminar said:
Wouldn't there not be...
:D I doubt this is a purposeful double negative!?

... a pressure gradient between the cappilaries at skin level and the heart? I don't remember how fluid in a complex system like a human body transmits pressure.
As far as I understand, pressure exerted in a closed system of fluid, induces equal pressure throughout the fluid and upon its containing environmnet. Therefore, the pressure created by the pump, the heart, is the same pressure exerted at all locations in the system by the blood.

This reasoning is used in describing hydraulic systems.
 
laminar

laminar

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Aug 13, 2001
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Okay,wouldn't not not not be? rofl

So heart exerts pressure A through circulatory system.
Ocean + atmosphere exerts pressure B throughout water column.
Is skin, muscle and fat considered to be water or something else?

For example, if my foot is surrounded by 10 Atm of pressure and my heart can only pump to the functional equivalent of 5 Atm of pressure, I wonder what pressure the blood in my foot is at?

Anyone know if someone's got the answer to this?

Pete
 
laminar

laminar

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Aug 13, 2001
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If the heart can always match the water column's pressure, then there would be no physical reason for blood to not to circulate in the extremities, it would be done for another reason (oxygen saving? core organ protecting?)

Pete
 
tylerz

tylerz

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Jun 19, 2002
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A thought/theory just occurred to me. It is possible that a certain state of mind, or partial pressure of gasses, or a combination thereof triggers the synthesis and release of hormones. As they are released into the blood these hormones induce a vasodilation of core arteries and therein giving the effect of the blood shift which we, maybe mistakenly, take to be caused by vasoconstriction.

The rationale:
- hormones would reach the core arteries first and be used up before reaching further along the arteries towards the extremeties, therefore the vasodilating effect would be isolated.
- control of the release of hormones is often affected by states of mind.
- hormones are also released in response to variances in chemical substances or properties.

Anything that suggests it can not be so?
 
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tylerz

tylerz

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Jun 19, 2002
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laminar said:
So heart exerts pressure A through circulatory system.
Ocean + atmosphere exerts pressure B throughout water column.
Is skin, muscle and fat considered to be water or something else?
Considered to be fluid filled flexible containers (ie. bags full of water).

For example, if my foot is surrounded by 10 Atm of pressure and my heart can only pump to the functional equivalent of 5 Atm of pressure, I wonder what pressure the blood in my foot is at?
Here is an interesting concept. The pressure at 10m deep is 2 Atm = 29.14 lbs/square-inch = 1520 mmHg. Normal blood pressure is below 140/90 mmHg.

Your heart is a muscle which generates the pressure based on its contraction. The contraction does not fight the pressure of the surrounding fluids, because those pressures are equally distributed and equally pervasive throughout all the tissues and fluids. The heart itself and all its cells are experiencing the same pressure. Since it is equal all throughout it balances out essentially to no pressure. Therefore the contraction and all other functions, not affected by gas compression, continue to operate as at atmospheric pressure. This means the contraction of the heart will still create a measureable relative 140/90 mmHg if the device was calibrated for the 2 Atm.

A couple concepts that should prove some of the points above:
- take a balloon and pull it under water; notice how the top becomes bulging and tight even though a small amount is under the water? The pressure on the part under the water is experienced by that part of the balloon that is above the water as well. Relate this to the idea of your foot being at a different depth than your heart.
- at 5m stretch your arm out, then suddenly contract your bicep until your forearm rests on your bicep. At 50m perform the same action. If the pressure at depth can affect your hearts contraction, then it should affect affect your bicep contraction, and therefore you would expect to find yourself having a harder time to contract your arm. However, this doesn't happen, does it?

This is all coming from deductions in this noggin of mine, which is maybe affected by all the changes in pressure these days, so definately challenge this and try to confirm it to be accurate or inaccurate.

Cheers,

Tyler
 
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