I’m doing emergency rescue for work and learnt that inhaling a few times at below 10% oxengenated air will leave you pretty much immobile, but I can hold my breath for at least a minute, so shouldn’t I be able to go without 02 for a similar amount of time? Sorry if this is smoothbrained, I tried googling it and couldn’t find an answer for this specifically.
In: Biology
When you hold your breath you have a lung full of 21% oxygen. You can’t possibly hold your breath long enough to deplete your lungs of oxygen and, therefore your blood oxygen will remain adequate to feed your brain. Breathing 10% oxygen will quickly lower your blood oxygen levels to brain-dangerous values.
Pretend your lungs are a restaurant. Your blood cells are the patrons, and the oxygen you breathe is their food. If you breathe in, the buffet fills with food. For as long as you’ve breathed in, blood cells can take food from the buffet until it runs out. This takes about a minute to run out, but that’s not something you need to worry about generally. Even though they can only survive without eating for a little while, you breathe frequently enough and deep enough there’s enough food to go around. When you breathe out, that’s like management throwing away the leftovers at the end of the day so there’s room for fresh food the next day.
If you breathe in a no oxygen environment, the patrons show up at the restaurant to empty plates and they begin to starve since they have no food. That’s when you start to rapidly lose cognitive function.
If you were to hold your breath in an oxygenated environment and move to a low oxygen environment, you would be fine until you exhaled since the buffet patrons still have food to eat for a while. When you exhale though, all of it is thrown away and replaced with empty dishes and the “starvation” clock starts up and you have just a few moments to function since nobody is being fed anymore.
The other answers are mentioning that a single breath of normal air has enough oxygen for more than one breath, but that still doesn’t explain why you can get more than two or three times as long out of a held breath, and can get 10 or 20 times as long instead.
Your body doesn’t have a low-oxygen response. It has a high-CO2 response. When you hold your breath, CO2 begins building up in your blood, and within 10 seconds, your heart rate is already falling, the pathways to your limbs are constricting, the spleen is releasing extra red blood cells from storage to extract every last molecule of oxygen from your lungs, and everything in your body is focusing on the single goal of keeping oxygenated blood going to your brain. In fact, for at least a few moments, the oxygenation of your brain will *increase* compared to normal, so you don’t feel faint.
If you enter a low oxygen environment without realizing it, you’re able to keep expelling CO2. Your heart rate doesn’t change, your limbs remain equally oxygenated as your brain (dividing a very low supply), and your blood cell volume does not increase. Your brain’s oxygenation will drop fast, and that makes you faint.
An anectode to answer your question: I recently went to a hypoxia chamber. When we were in the chamber which was filled with nitrogen, and the test had concluded, the instructor had us do lung packing with our oxygen masks on, so that we could quickly take off our masks, sanitize them, and then leave the chamber without becoming hypoxic again.
Because low oxygen jmales you dizzy and pass out. You dtill are getting oxygen so your body slow down.
Holding your bresth is depriving your body of oxygen, building up Co2 in your bloodstream causing the PANIC mode to kick in.
This is a fantastic question! I will try to truly ELI5, so forgive some of the simplification.
To understand the answer, it is important to understand how we breathe. Breathing is something we don’t have to think about, and our lungs basically “trade” oxygen for carbon dioxide.
Carbon dioxide is constantly being produced by your body and is a waste gas, and oxygen is used to make energy.
How does our body know when to take a breath? It is when the carbon dioxide levels (CO2) gets too high. This is so cool! We don’t rely at all on knowing if the oxygen levels are too low, only if the waste gas of CO2 is too high!
That means if you hold your breath, the CO2 keeps building up and eventually your body will start breathing again to get rid of it.
BUT, if you are in an environment where there is low oxygen, you will keep breathing out the CO2, but not making a good trade for the oxygen your body needs to run. You won’t even notice or feel like you aren’t breathing. That is because as long as the waste CO2 is being exhaled, your body won’t feel like it isn’t breathing!
Now that you know this, you can use that in a fun way. If you are in a contest to see who can hold your breath the longest, hyperventilate (breath really heavy like a panting dog) for a minute before you start. You will get rid of so much CO2 that your body will take longer before it triggers you to breath again!
Because the sensation of needing to take a breath is not because your body wants oxygen, but because your body has to get rid of the CO2.
When you breath low oxygen air, your body doesn’t realize it is suffocating, and your blood oxygen level slowly drops, and you basically get high and loopy, then you pass out and die. The whole time, you never realize you are dying.
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