I studied that if someone stops breathing by pressing their nostrils with fingers and start to starve without oxygen, the body will automatically cause the hands to leave the nostrils in a certain time so that we can breathe. (a kind of reflex, I guess)

What is this certain time?

  • $\begingroup$ Could you include a source for where you studied that? Thanks. $\endgroup$ – user438383 Dec 31 '20 at 10:46
  • $\begingroup$ I found it in many sources, one is healthline.com/health/holding-your-breath#what-happens $\endgroup$ – Fghj Dec 31 '20 at 10:54
  • $\begingroup$ Have u seen the above comment @user438383 $\endgroup$ – Fghj Dec 31 '20 at 13:12
  • 2
    $\begingroup$ The link you gave doesn't say anything at all about the body "automatically" causing the hands to leave the nostrils. That will happen when you black out, as your muscles become flaccid and gravity causes your hand to move away from your face, but there's no "automatic" movement... $\endgroup$ – MattDMo Dec 31 '20 at 21:18

Your respiratory system has quite a number of neural and non-neural (e.g., physical, emotional, and chemical factors) controls in addition to the ability to be voluntary controlled.

  • A strong influence on much of our respiratory physiology is a response to changes in carbon dioxide in the blood (well, more specifically, it's blood pH that is regulated). Oxygen homeostasis is also controlled.

As a result, the duration you're asking about almost certainly is dependent on total lung capacity, actual volume of air inhaled, diffusion capacities, activity levels, etc. as each of these would determine levels of oxygen and CO2 in the blood and available to tissues (such as the brain).

  • In other words, since gas homeostasis plays such a prominent role in respiratory control, the duration of any "reflex" response would vary between person to person (based on their anatomy) and even for an individual person based on circumstances.

Also, I'm not personally familiar with any such reflex that you mention.*

  • In fact, some children intentionally hold their breath until they pass out! This passing out is actually a useful adaptation because it allows the body to return to using involuntary breathing controls to prevent the child from depriving themselves of oxygen long enough to induce death. Seattle Children's Hospital suggests normal breathing returns in under 2 minutes.

  • Also see the fainting game that got popular among teens earlier this century that involved intentionally causing self syncope. [WARNING: DON'T BE THIS STUPID]

* If you can update your question with a source or any additional information about the "reflex" you mention, I or someone else might be able to address the reflex or your source of info more specifically.


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