Breathing II: Anatomy
Originally published on the 5th of July 2018
“With all the techniques of breathing that I’ve explored over about 50 years, the one that works best for me is to awaken my awareness and then to be effortlessly breathing rather than focusing on my breath. And what that has done is taken the breath to the cellular level away from even the lungs and the diaphragms, coming to the place of just letting your breath breathe.”
– Bonnie Bainbridge Cohen
Here is a follow up to my previous blog.
This is about the anatomy of breathing – something I feel is greatly misunderstood.
So what is our starting point? We know we have lungs, and nostrils and a diagraphm and all that stuff. I am not going to go into that. There are thousands of sources you can find which will explain that. I will assume, therefore, you have some very basic knowledge of the anatomy of the lungs.
What I am more interested in sharing with you is the microanatomy of breathing.
What nobody tells you about are these muscles:
Note where it says: “smooth muscle”
This image shows some very, very fine muscles surrounding the broncioles. These branch out from the bigger bronchus, and lead to the alveoli, which is where the greatest surface area for gas exchange takes place.
While there are some alveoli in the bigger air passages, these “bunches of grapes” are, by a hugely disproportionate extent, where the oxygen gets into the blood (and the carbon dioxide out of it).
The bronchioles, which have these muscles around them, are about as wide as a hair, and the muscles have an interesting mechanism by which they work.
Obviously when you do your standard breathing practices “Take a deep breathe in etc”, you are not influencing these tiny muscles directly with your conscious mind. You are probably mostly able to influence the muscles of your rib cage, and to a certain, lesser extent, your diaphragm.
So here’s where, in my nerdy opinion, it gets interesting.
The way these muscles work is that they depend on the oxygen saturation of the blood. When there is enough oxygen, they contract, meaning that hardly any air can get into the alveoli. When the oxygen level drops below a certain threshold, they do not have the capacity to keep contracted and they release.
This creates the sudden effect of the majority of the lung capacity to open up – imagine something like the surface area of a football field worth becoming available all with the releasing and opening of these muscles.
And then what happens? — whoosh — you get a gorgeous, natural unforced inbreathe.
Hopefully, you are, at this point, not gripping your ribs or abdomen or pelvic floor or shoulders or wherever and your diaphragm is free. Those muscles can SECONDARILY pick up what’s going on, let it happen and engage (both shortening and lengthening depending on the muscle) in their beautifully co-ordinated way to support the natural inbreathe.
Now, to be clear, I have nothing against that you learn about and try and work with these secondary muscle actions.
But if you do not allow the natural, unforced inbreathe first, which comes from the release of the tiny muscles over which you have virtually no control, then it is pretty much useless. When you force the inbreathe prematurely, all that happens is that you fill up the bronchus, with its relatively tiny surface area, and use almost as much oxygen as you gain.
This is called shallow breathing.
A lot of the “deep breathes” you try and take, may actually be shallow.
The natural physiology of the inbreathe is the basis for the instruction:
Exhale fully, and allow the inbreathe to come naturally.
It is extremely important to WAIT out that time for the inbreathe.
While you are still, and you are wondering if you are ever going to breathe in, your cells are burning oxygen and your oxygen saturation in your blood is dropping. THEN you hit that beautiful tipping point.
It happens in the BLOOD. Not in the mind. Not in the diaphragm.
A final point, is that as I understand it, the nerves which supply the diaphragm are a mix of autonomic and somatic nerves. The medical mainstream has tended to view the diaphragm predominantly as in terms of the Somatic component but I understand the research is starting to swing more towards the autonomic innervation.
To put this into (slightly more) normal English, this means that your diaphragm has less conscious control than “involuntary” influence. Yes you can engage it when you “breathe in” but not in the same way as you can do a “rep” on, say, your biceps.
In order words, although it is a muscle, it might be helpful to think of it more as an organ. This is a useful metaphor in the sense that the autonomic (greatest) proportion of your diaphragm you can influence to roughly the same extent as you can influence your stomach.
Take another look at the invitation of the last post:
Breathe out fully, then wait for the inbreathe to come.
Try it out, and enjoy.