True? Body's impulse to breathe is based on CO2?

[Bob]

Not the need for oxygen, but the need to expel carbon dioxide?

[harrisonh]

Yep! The buildup of CO2 in blood, specifically. That's why when euthanizing animals for scientific purposes, it is considering more humane to use another gas such as nitrogen to suffocate then as there's no suffering, they just eventually go to sleep.

[Bob]

Haha.  Interesting.

I heard about people hyperventilating and mountain climbers. 

Something about this...
https://en.wikipedia.org/wiki/Cheyne%E2%80%93Stokes_respiration

I think mountain climbers tire, fall asleep, and then their breathing slows down because their body doesn't have much CO2 in it.  But they still need oxygen.  And that's how they go.

[j_menz]

In my case, I fear it's more the need for nicotine.

[lloyd_cdb]

In my case, it's just to give me the opportunity to let out loud disdainful sighs.

[iansinclair]

In my case, I fear it's more the need for nicotine.

Oh yes indeed!  I'm right with you there!

[oxy60]

Isn't basic physiology being taught in schools anymore? Are we totally dependent on our medical professional to answer the most basic of questions?

Yes, there are some complicated processes of which the understanding will be based on on detailed knowledge.

Sorry Bob, but I am shocked that you didn't know the answer and had to ask here. Or was this a kind of joke?

[Bob]

No joke.  I never thought it about it before.  It doesn't come up often.  And it sounds kind of opposite of what I would have thought at first.  The body needs oxygen, so it takes a breath.  Of course. But not apparently.  The body's trying to rid itself of CO2 so it breathes. 

[hardy_practice]

Check out the Buteyko Method.

[faulty_damper]

Isn't basic physiology being taught in schools anymore? Are we totally dependent on our medical professional to answer the most basic of questions?

Umm... are you talking about high school?  Because this was not even offered.  I had to take a course in college to learn about it.

====
This is my understanding of breathing:

You inhale so that you intake O₂, O₂ binds with C and becomes CO₂, and then you exhale CO₂.  Oxygen functions as a garbage collector, picking up left over carbon. But before it binds with C, O₂ needs to receive an electron after the Krebs cycle, otherwise known as the electron transport chain.  Only when it has an available electron can it bind with C forming CO₂.

[oxy60]

Umm... are you talking about high school?  Because this was not even offered.  I had to take a course in college to learn about it.

Yes, high school, as part of our class in biology. We learned the basics (not the complicated explanation you quoted) of our bodies. We even took each others blood pressure. I was able to follow your complicated explanation of breathing based solely on what I remember from my high school physics course.

[Bob]

Oxygen in, CO2 out.  Yes, covered in grade school.

The part about the impulse to breathe depending on a CO2 buildup wasn't covered for me.  It would make more sense if it were trigged by both, need for oxygen and need to expel CO2.

[lloyd_cdb]

Some of the stuff, while covered, isn't taught for children to understand it but just to learn it. I think back on some of my math courses and it's no wonder 95% of the class had no idea what was going on. Instead of learning what the formulas meant, we learned to memorize them.

Everyone learned O2/CO2 in grade school. I think every idiot knows we (intentionally) inhale oxygen and exhale carbon dioxide. It's that the specificity of the impulse comment was new to me as well. I understand O2 is a requirement in cell function and CO2 buildup decreases pH of the blood. It comes down to which issue is a more immediate threat to your body. Apparently CO2 buildup has a faster negative effect than O2 deficiency. This I didn't know, and is one of those things that I guess is similar to the math formulas.

[faulty_damper]

I was wrong: the Krebs cycle is not the same as the electron transport chain.  The Krebs cycle occurs right before the electron transport chain.

[oxy60]

I was taught in grade/high school that during exercise the muscles release CO2 causing us to exhale. Also taught was that exercise converts fat to muscle thereby decreasing the need for insulin in diabetics.

I have no idea how all this hooks together...

[timothy42b]

There are still some mysteries about the impulse to breathe being researched.

What is really weird is that the record for holding your breath is 22 minutes 22 seconds.

No, not 2 minutes 22 seconds, it really is 22 minutes.  Tom Sietas is his name.

But yes, we all learned the oversimplified version of CO2 control in high school.   

[lloyd_cdb]

Inhalation is done by muscle contraction creating a vacuum effect and exhalation is done through the muscle relaxing, but it's not CO2 being released from the muscles per se. I think the best way to say it is that it is mechanically released, not chemically released.

To my knowledge, fat never turns into muscle. It's a completely different mechanism where your body builds muscle while getting rid of fat, but not a conversion. Although I don't really know specifics of diabetics.

I believe that the CO2 buildup is due to cellular respiration where O2 binds within the cells to store energy, releasing CO2. The CO2 then acidifies the blood, and then needs to be released through exhalation.

Again though, specifics are a bit hazy. The cellular respiration part is only from researching it yesterday It was something about ATP or whatnot...

[nyiregyhazi]

Not the need for oxygen, but the need to expel carbon dioxide?

It's a matter of how you frame it surely? This isn't an A or B situation.If you've breathed out, your body breathes in to get oxygen. If you've breathed in, your body breathes out both to expel CO2 and to prepare for more oxygen. It doesn't really make any sense unless you look at it from both angles.

[nyiregyhazi]

There are still some mysteries about the impulse to breathe being researched.

What is really weird is that the record for holding your breath is 22 minutes 22 seconds.

No, not 2 minutes 22 seconds, it really is 22 minutes.  Tom Sietas is his name.

But yes, we all learned the oversimplified version of CO2 control in high school.    

That's the same stunt David Blaine did- after breathing pure oxygen though, yeah? I'm pretty sure the record is considerably lower without that kind of preparation.

(incidentally- the fact that you can hold your breath longer after pure oxygen seems to make it very unlikely that you could see breathing as being about ridding you of carbon dioxide "instead" of taking oxygen in. I don't believe having a lot of carbon dioxide in the lungs specifically harms, does it? Surely the problem is the lack of oxygen in the same gas, once you've turned it all into carbon dioxide? I'm not convinced there's any need for a rethink on what people usually believe.)

[lloyd_cdb]

This isn't an A or B situation.

This is exactly how I always looked at it. On the other hand, it's about comparing the negative effects of both sides of the coin. If one has a greater/quicker negative effect, the body would have no reason to base it's involuntary actions on something less necessary. I sincerely doubt your involuntary heart beat is triggered because your toes get cold without it. Obviously that's a functional aspect of it, but I doubt it actually contributes to the involuntary reaction. Considering there are only 2 major functions of breathing, it's something we all might take for granted and over-simplify our way of approaching it.

All that being said, I'd still agree with you, I just wanted to point out my thought process in contribution to the discussion. I'm probably over-thinking the hell out of this.

[lloyd_cdb]

I don't believe having a lot of carbon dioxide in the lungs specifically harms, does it?

It's not in your lungs, it's in your blood stream. CO2 in the bloodstream has an immediate and drastic effect on the pH of your blood which can only stand very small changes.

[Bob]

And if you could scrub the CO2 from your blood some other way, your body wouldn't feel the the need to suck in more air.  You'd pass out from lack of oxygen then.  Not that that comes up too often.

[nyiregyhazi]

It's not in your lungs, it's in your blood stream. CO2 in the bloodstream has an immediate and drastic effect on the pH of your blood which can only stand very small changes.

I'm talking about when it's left to accumulate in the lungs. Why can you last longer after breathing in pure oxygen than after breathing normal air? There's no rational reason why this would be so, if the urgent need to breathe were founded more greatly upon the need to expel carbon dioxide than to absorb oxygen. It's clearly more to do with oxygen intake, in that scenario- which seems to make a mockery of the idea that the instinct is based more on a need to expel carbon dioxide more than to take oxygen in. I'm not aware of any reason why having breathed oxygen would help you last longer without needing to expel carbon dioxide, if that theory is accurate. Although it's a pretty pointless issue anyway, given that breathing necessarily serves both roles, I'd be interested to know what supposed evidence there is and how the oxygen breathing scenario might possibly be explained away - except by the fact that you can repress the urge to breathe simply because you have more oxygen saved up.

[timothy42b]

I'm talking about when it's left to accumulate in the lungs. Why can you last longer after breathing in pure oxygen than after breathing normal air? There's no rational reason why this would be so, if the urgent need to breathe were founded more greatly upon the need to expel carbon dioxide than to absorb oxygen.

You're using logic.  And I can't fault it.

But this one is counterintuitive.  You're simply wrong.  The mechanism that the body uses is to measure the CO2.  The pathways are well understood.  This is how breathing is ramped up during exercise and down during sleep, for example.  Check any biology book. 

The long duration breathholder has to suppress the urgent need to breathe.  This is a learned skill that has yet to be fully investigated.  Hyperventilating with either air or oxygen delays that impulse, because it removes the existing CO2 in the lungs more completely, which in turn reduces the CO2 in the blood. 

[nyiregyhazi]

You're using logic.  And I can't fault it.

But this one is counterintuitive.  You're simply wrong.  The mechanism that the body uses is to measure the CO2.  The pathways are well understood.  This is how breathing is ramped up during exercise and down during sleep, for example.  Check any biology book.  

The long duration breathholder has to suppress the urgent need to breathe.  This is a learned skill that has yet to be fully investigated.  Hyperventilating with either air or oxygen delays that impulse, because it removes the existing CO2 in the lungs more completely, which in turn reduces the CO2 in the blood.  

Why would oxygen remove the CO2 more completely than regular air? If it does, it shows that that these things are two sides of one coin. It strikes me as meaningless to say that we breathe to release CO2 "instead" of for oxygen. We need oxygen to do so. Even if the trigger is CO2, that doesn't make it any less part of the complete cycle.

What happens if someone breathes in a pure inert gas? It would be perfectly possible to dispense with CO2 on out breaths. Would that not cause the person to try to breathe faster in a bid to gain oxygen? Or is this a situation in which this makes a genuine practical difference?

[lloyd_cdb]

I'm talking about when it's left to accumulate in the lungs.

I was saying that the issue is with the bloodstream, not the lungs. Lung function isn't there to have different air molecules sitting in your lungs. When your lungs fill with CO2, the pathways that scrub CO2 out of the blood become backed up/blocked, which causes the negative effect of lowering pH in the blood.

Like I said though, I do actually agree that it's a function of both, I'm just approaching it in a different way than I normally would think about it.

Why can you last longer after breathing in pure oxygen than after breathing normal air?

It's called hypocapnia, which is triggered by hyperventilation. It's when you see swimmers breathing quickly before trying to hold their breath. It reduces respiratory drive by lowering the CO2 concentration in your blood. What this does is reduce the body's belief that it needs O2 due to the Bohr effect. The Bohr effect points to a cause/effect relationship between CO2 and O2, not just a correlation.

The subject at hand is most likely due to the fact that they hyperventilate before even inhaling the O2. Effectively doing what is normally done to increase holding your breathe, and then to fill an extra supply of O2 in your lungs so your body takes longer to black out, which then returns your breathing to normal.

Although it's a pretty pointless issue anyway, given that breathing necessarily serves both roles

It's pointless in that all of us are currently breathing right now, but it's just a discussion point. We aren't trying to figure out how to get our bodies to force us to breathe so we don't die while discussing this.

Why would oxygen remove the CO2 more completely than regular air? If it does, it shows that that these things are two sides of one coin. It strikes me as meaningless to say that we breathe to release CO2 "instead" of for oxygen. We need oxygen to do so. Even if the trigger is CO2, that doesn't make it any less part of the complete cycle.

Again, the O2 isn't removing the CO2 more completely, it just allows you to stay conscious longer while your CO2 level is returning to normal. Obviously these are two sides of a coin, and nobody is arguing that it isn't part of the cycle. It's purely about the trigger mechanism. As I said earlier, keeping your toes warm is part of the complete cycle of the heartbeat, but I sincerely doubt it has anything to do with the trigger mechanism.

What happens if someone breathes in a pure inert gas? It would be perfectly possible to dispense with CO2 on out breaths. Would that not cause the person to try to breathe faster in a bid to gain oxygen? Or is this a situation in which this makes a genuine practical difference?

Again, based on the Bohr effect, the hyperventilation is for the reduction of CO2 in the body, thus tricking yourself into believing you need less O2.

You need to breathe either way which is why I agree with you in actual practice. In theory though, it could actually have some basis of truth.

[nyiregyhazi]

If you are breathing inert gas, wouldn't you be able to dispense with co2 just as well? I'm with you on the other points, but if the idea that the trigger is purely about co2 is true, presumably you wouldn't have any stronger breathing reflexes despite absence of oxygen? I'm not sure if this is what would happen or not, but this strikes me as the only practical situation where the difference could be tested.

[lloyd_cdb]

Yeah, I actually misinterpreted you the first time. That is a very valid situation for a counterargument. I vote sticking Bob in a room and testing it on him. He brought it up in the first place.

My one argument against that would be voluntary vs. involuntary. That might be a panic situation where you are intentionally breathing from fear/knowledge of potential harm before your body even reacts. When holding your breath, your are restricting both voluntary and involuntary urges. Whether it's because you have control over involuntary urges in certain situations or that your body isn't even triggering it is also up for debate.

Regardless, it's a tough situation to test in practicality which is why I agree about a 2-part system in the first place. It's fairly irrelevant, just an interesting theoretical topic.

[timothy42b]

but if the idea that the trigger is purely about co2 is true, presumably you wouldn't have any stronger breathing reflexes despite absence of oxygen? I'm not sure if this is what would happen or not, but this strikes me as the only practical situation where the difference could be tested.

It's the only practical thought experiment.

Biologists are not limited to thought experiments.  They can even do dissections!  And they've traced the sensors that measure CO2, not O2, and the control pathways that speed up the breathing.

You insist on arguing with the established body of science.  Maybe it would make more sense to design the body some other way, but this is the one we have.

I'm not sure why that's so difficult to accept.  Have you really never taken any science classes? 

[nyiregyhazi]

It's the only practical thought experiment.

Biologists are not limited to thought experiments.  They can even do dissections!  And they've traced the sensors that measure CO2, not O2, and the control pathways that speed up the breathing.

You insist on arguing with the established body of science.  Maybe it would make more sense to design the body some other way, but this is the one we have.

I'm not sure why that's so difficult to accept.  Have you really never taken any science classes?  

Yes, I took science classes. They told me to demand proofs/empirical data before casually accepting something on the grounds that someone else made an assertion (if there are factors that logically cause questions to be raised).

The scientific method is precisely why I proposed the breathing of pure inert gas. If someone breathes it without knowing and breathes normally, it proves that carbon dioxide is indeed the trigger (yet does not prove that we breathe to emit carbon dioxide "instead" of to receive oxygen- given that evolution never occured under such synthetic circumstances). Alternatively, if breathing accelerates, it illustrates that lack of oxygen triggers increased breathing (regardless of the rate of carbon dioxide release).

If that falls foul of scientific procedure, please be my guest in presenting whatever omissions compromise it.

[nyiregyhazi]

Yeah, I actually misinterpreted you the first time. That is a very valid situation for a counterargument. I vote sticking Bob in a room and testing it on him. He brought it up in the first place.

My one argument against that would be voluntary vs. involuntary. That might be a panic situation where you are intentionally breathing from fear/knowledge of potential harm before your body even reacts. When holding your breath, your are restricting both voluntary and involuntary urges. Whether it's because you have control over involuntary urges in certain situations or that your body isn't even triggering it is also up for debate.

Regardless, it's a tough situation to test in practicality which is why I agree about a 2-part system in the first place. It's fairly irrelevant, just an interesting theoretical topic.

Yeah, fair points. it would be interesting to do the test with inert gas on an unwitting victim, where psychology is not a factor. Presumably there would be no change in their rate of breath?

[j_menz]

it would be interesting to do the test with inert gas on an unwitting victim, where psychology is not a factor.

Love to see your ethics committee proposal for that one. 

[nyiregyhazi]

Love to see your ethics committee proposal for that one. 

They've done a lot worse in the past. Political correctness gone mad, if you ask me :-)

[timothy42b]

This is long established science.  Here are a couple of snips from the Journal of Respiratory and Critical Care Medicine.

The bulbopontine “respiratory centers” became a focus for investigation of the neural processes controlling the automatic or metabolic ventilatory regulation. Clusters of inspiratory and expiratory neurons were found to be located in the pons and medulla (9). It became apparent that inspiratory and expiratory neurons provided mutually inhibitory interactions and that phase-switching of the central pattern generator could be initiated via internal feedback that involved neurons of the rostral pons (10). The so-called respiratory centers were given anatomic definition by grouping neurons into two major clusters; the dorsal respiratory group in the vicinity of the nucleus of the tractus solitarius, and the ventral respiratory group near the ambiguus nucleus (11). The latter was found to lie in a prolonged column stretching from the caudal pons to the facial nucleus and exhibited topographical clustering of expiratory and inspiratory neurons at discrete points throughout this nucleus (12). Pontine neurons were found to lie in the nucleus parabrachialis medialis and in the Kölliker-Fuse nucleus (13). The latter was found to be particularly responsive to vagal feedback; which lead to the notion that phase switching occurred in the rostral pons (14).

A major breakthrough in the investigation of central neural control of breathing occurred when Richter perfected techniques for the intracellular recording of bulbar respiratory neurons (15, 16). Although extracellular recordings could provide a “digital” analysis of the respiratory network, intracellular recording of membrane potential of the bulbar respiratory neurons provided an “insider's view” of the dynamic interaction among respiratory neurons. Essentially, respiratory fluctuations of membrane potential reveal the sequential arrival of excitatory and inhibitory post-synaptic potentials whereby respiratory neurons “communicate” with one another. In addition, these recordings allowed systematic identification of various respiratory neurons synaptically interconnected principally by inhibitory mechanisms (17). Further, these techniques led to the understanding that the neurorespiratory cycle consisted of three, not two, phases: inspiration, post-inspiration, and neural expiration (18, 19). These findings reveal that the expiratory component of the neural-respiratory cycle has two phases: an early-expiratory (post-inspiratory) and a late expiratory phase (20, 21). This division of expiration into two phases is in accord with neuromechanical observations in unanesthetized mammals showing that during the first phase of expiration airflow is retarded, whereas during the second phase it is accelerated (4). In addition, this three-phase respiratory cycle appears to derive evolutionarily from a three-phase neuromechanical ventilatory cycle that may be observed in amphibians and reptiles.

The point of that snip is that this is based on actual research, not armchair pontification.

There has been substantial progress in the understanding of central respiratory chemoreception during the last 50 years. Considerable progress was achieved in two seminal studies performed in the mid-1960s. One was the work of Loesche and colleagues, who located central respiratory chemoreceptors sensitive to CO2 and pH on the ventral surface of the medulla (27). The other was the landmark experiments by Pappenheimer and associates illustrating that brain extracellular fluid pH and Pco 2 regulate pulmonary ventilation (28) and that the receptors to pH and Pco 2 could be theoretically localized along a diffusion gradient between the blood and the CSF (29). More recent studies by Nattie and colleagues have demonstrated that central respiratory chemoreception is located at a variety of sites within the brainstem, and probably are located in the same areas that are important for respiratory rhythmogenesis and pattern control (30). Major unresolved questions currently under investigation include: are respiratory neurons chemosensitive? Is chemoreception related to intra- or extracellular pH? What is the membrane biophysical mechanism responsible for transduction of the H+ signal? Answers to these questions are on the horizon, suggesting that investigation of cellular and molecular basis for central respiratory chemoreception will yield major insights in the next decade.

And that one tells a little more about the processes involved.

I have no doubt that N will not consider altering his unshakeable beliefs, despite the world's physiologists being in complete disagreement. 

[nyiregyhazi]

This is long established science.  Here are a couple of snips from the Journal of Respiratory and Critical Care Medicine.
 

The point of that snip is that this is based on actual research, not armchair pontification.
 

And that one tells a little more about the processes involved.

I have no doubt that N will not consider altering his unshakeable beliefs, despite the world's physiologists being in complete disagreement.  

If my beliefs were unshakeable, I would not have posed the question about inert gas. Rather than give all the technicalities, could you simply answer what the result would be in that scenario? Would the breathing be unchanged? If so, what is the direct evidence?

Nothing in the paragraphs you gave either states or proves that breathing functions around CO2 "instead" of oxygen. Merely illustrating that there is sensivity to CO2 (which surely didn't demand quite such long paragraphs with quite so much contextually irrelevant information - given that the whole of your first excerpt didn't even reference oxygen or CO2 issues?) does not discount the possibility that there is also sensitivity to oxygen, if you utilise the most basic logic. I'm still interested in the answer to my question- rather than in reams of almost entirely contextually irrelevant writing.

[timothy42b]

I'm still interested in the answer to my question- rather than in reams of almost entirely contextually irrelevant writing.

They seem irrelevant because you don't have a background in physiology.  That lack of background severely limits your ability to come up with your own theories about how the body works or should work. 

I know it is difficult to accept but your piano expertise does not transfer to biology.  There are some fields where you have to know the basics before you can reject the body of knowledge accepted by the experts. 

Those snips should have illustrated that, if nothing else.

[nyiregyhazi]

They seem irrelevant because you don't have a background in physiology.  That lack of background severely limits your ability to come up with your own theories about how the body works or should work.  

I know it is difficult to accept but your piano expertise does not transfer to biology.  There are some fields where you have to know the basics before you can reject the body of knowledge accepted by the experts.  

Those snips should have illustrated that, if nothing else.

They seem irrelevant because they failed to reference the issue that you presented them in supposed reference to. How is a two paragraph source without a single reference to either CO2 or oxygen supposed to be of specific relevance to the crux of this? I'm willing to consider that the body does not actively have a mechanism that triggers breathing in response to shortage of oxygen, but I'd have hoped for a source that actually deals with the issue rather than a load of jargon that fails to either state or illustrate that.

Also, you can drop the strawman. I didn't reject the idea. I asked for the specific explanation for apparent logical discrepancies and for specific proof. If you believe in scientific method, you should be aware that establishing a detection mechanism for CO2 in no way "proves" that breathing cannot also be triggered by oxygen shortage. Surely you could have found a source that has something both more relevant and concrete?

[timothy42b]

Surely you could have found a source that has something both more relevant and concrete?

You are the one who disagrees with the standard wisdom presented in high school and college level science classes about how these systems function. 

(You appear blissfully unaware of what is normally taught - this is clearly a new idea to you.) 

Perhaps it is time to do your own research.  Long experience tells me you will be resistant to ANY information I am able to find. 

[nyiregyhazi]

You are the one who disagrees with the standard wisdom presented in high school and college level science classes about how these systems function. 

(You appear blissfully unaware of what is normally taught - this is clearly a new idea to you.) 

Perhaps it is time to do your own research.  Long experience tells me you will be resistant to ANY information I am able to find. 

Another straw man. Instead of attributing opinions to me that I don't hold, how about a link to specific proof? I'm nothing but interested in direct evidence. I'm just curious as to why you presented such minimally relevant sources instead of something that pertains to this.

[oxy60]

It is becoming painfully clear that the world is not uniform. What is clear to some is not clear to all. What some of us know to be the obvious case is not obvious to all.

There are candidate Phd's who get published with their degree arguing against the obvious. Or proposing off the wall ideas.

Just because there are no studies that prove it won't work doesn't mean it will!

[Bob]

Someone sent me this...





I hoped someone would eventually run with your premise (which makes sense, and is probably the first draft (i.e. ver 1.0) of respiratory drive futher back down the evolutionary ladder, that is, a system this complex (if we follow an evolutionary biology perspective, or even intelligent design) did not just happen by accident. I don't post in the forum (and very seldom log in) as I created an account to access sheet music, but here is some further reading:

https://faculty.mdc.edu/ppitayap/COPD%20patient%20CO2%20toxicity.htm

Basically, think about the body's adaptation mechanisms, or rather, a good way to understand how something complex works is to sometimes look at instances where it is broken and still works, then back into original question and answer (can leed to a deeper understanding).

[timothy42b]

 your premise (which makes sense, and is probably the first draft (i.e. ver 1.0) of respiratory drive futher back down the evolutionary ladder, that is, a system this complex (if we follow an evolutionary biology perspective, or even intelligent design) did not just happen by accident.

When you look at the way living organisms function, whether at a biochemical level or simply a skeletal structural level, it is striking how much of the time parts are repurposed and reused for vastly different functions.  It certainly wasn't designed to work the way it does now - at most it was designed to work ten iterations back.  Because of this, arguments that something is too complex not to be designed fall a bit short. 

Now that the CO2/O2 systems have breathed their last, I have a startling new revelation.

The eye is backwards.  Backwards, I say, backwards!

You probably know we have rods and cones that are specialized cells that detect light, and form the lining of the retina.  Naturally they need nerves to carry the information to the brain, and a blood vessels to bring them food and remove waste. 

Well, believe it or not, the rods and cones point backwards.  The nerves and blood vessels are in front of them.  The light that enters your eye must pass through the nerves and blood vessels before hitting the receptors.  The nerve impulses must be gathered and sent back through the retina, leaving a blind spot where the optic nerve goes through. 

Now we'll pause while N explains that this doesn't make any sense, so it couldn't be true. 

[lloyd_cdb]

It is NOT backwards.


It's inside out.

[timothy42b]

You probably know that there are 10 distinct types of eyes in the animal kingdom, including some that use mirrors to focus rather than a lens, like a reflecting telescope. 

Clams, for example. 

[lloyd_cdb]

I would have thought there would be more than 10, but I guess it comes down to the definition of 'distinct'. I think of a spider having an eye cluster, but if each eye were the same in mechanical function as a human, I guess it wouldn't necessarily be 'distinct'.

[timothy42b]

If you're interested, here is the relevant text:

https://www.amazon.com/Animal-Eyes-Oxford-Biology/dp/0198509685

I got it through interlibrary loan. 

[j_menz]

It is NOT backwards.

No, TON is NOT backwards. 

[oxy60]

When you look at the way living organisms function, whether at a biochemical level or simply a skeletal structural level, it is striking how much of the time parts are repurposed and reused for vastly different functions.  It certainly wasn't designed to work the way it does now - at most it was designed to work ten iterations back.  Because of this, arguments that something is too complex not to be designed fall a bit short. 

Now that the CO2/O2 systems have breathed their last, I have a startling new revelation.

The eye is backwards.  Backwards, I say, backwards!

You probably know we have rods and cones that are specialized cells that detect light, and form the lining of the retina.  Naturally they need nerves to carry the information to the brain, and a blood vessels to bring them food and remove waste. 

Well, believe it or not, the rods and cones point backwards.  The nerves and blood vessels are in front of them.  The light that enters your eye must pass through the nerves and blood vessels before hitting the receptors.  The nerve impulses must be gathered and sent back through the retina, leaving a blind spot where the optic nerve goes through. 

Now we'll pause while N explains that this doesn't make any sense, so it couldn't be true. 

So if we do a retinal repair with laser are we shooting through those items? I thought the retina was the first thing we hit and it was the receptor. As well I don't know if the blind spot created by the optic nerve can be found by test.

[timothy42b]

So if we do a retinal repair with laser are we shooting through those items?

Yes, through six layers.
1  Nerve fiber layer
2  Ganglion cell layer
3  Inner plexiform layer
4  Inner nuclear layer
5  Outer plexiform layer
6  Outer nuclear layer

And now I must apologize for being a smart aleck.  I really thought everybody knew this. 

[Bob]

Please.  It's taught in grade school.  Everyone knows that stuff.  Haha.