The Breathing Process
This section is intended to give you a very simple explanation of the mechanics of breathing, along with a few stylized diagrams to illustrate what happens during the process of respiration.
Hopefully, this will give you a basic understanding of how each breath enters the body and where you can locate those parts of your anatomy that are involved. Once you have this fundamental knowledge, any instruction on breathing exercises or discussion on the breath throughout the website, should make sense for you.
You will need to look at a good anatomy and physiology reference book if you want more detailed information than I am presenting here. The diagrams, particularly, are uncomplicated representations of the breathing process.
Terminology
In general terms, at any given moment, we are either breathing IN or breathing OUT, which may also be referred to as INHALING and EXHALING, or INSPIRING and EXPIRING.
The other phases of the breathing cycle are when the breath is held IN after the inbreath, or held OUT after the outbreath. These may also be called BREATH RETENTION. Retention may naturally occur as a slight pause between the inhale and exhale, or between the exhale and inhale.
Now let’s get familiar with those pieces of anatomy that come into play during the act of breathing:
The breathing apparatus
Lungs
The oxygenated air we breathe in through the nose or mouth is destined to reach the two lungs, which are sac-like organs situated in the chest cavity (thorax). Here, the oxygen is transferred into the blood stream so that it can be transported to every cell of the body; remember, oxygen is the vital fuel to keep every cell working and to maintain our life and health.
As well as dealing with our oxygen intake, the lungs are also responsible for getting rid of carbon dioxide, which is the waste gas produced by the cells as a result of their using the oxygen. The carbon dioxide is transported from the cells to the lungs via the blood stream where it is released with the exhalation. Not all the carbon dioxide is excreted, as a certain amount in the blood stream is vital to our survival and healthy function.
So – in simplistic terms, the lungs take in oxygen, and expel carbon dioxide.
The lungs have a certain amount of elasticity in their tissue structure so that they can expand to receive the air intake, and deflate as air is expelled. The outer surface of the lungs is attached to the inner surface of the thorax.
Diaphragm
The diaphragm is a very strong and powerful muscle, shaped rather like a huge upturned saucer. It acts as a partition which completely separates the chest cavity from the abdominal cavity. It is attached to the base of the sternum at the front of the chest, to the lower ribs all the way from the front of the body round to the back, and also to the 2nd and 3rd lumbar vertebrae of the spine which are at about the level of your waist at the back.
And, in case you’re wondering how the top and bottom halves of your body actually ‘communicate’, rest assured they’re not functioning in total isolation! The diaphragm is perforated in the middle to allow the passage of vital veins, arteries, nerves, and also the oesophagus for taking food from the mouth to the stomach.
Being a muscle, the diaphragm is designed to contract and relax, just like the muscles that contract and relax to move our limbs and body. Contraction of the diaphragm results in flattening out its upturned saucer shape, and relaxation of the diaphragm allows it to return to its domed form.
Sternum
The sternum, or breastbone, is situated at the centre line of the chest. It acts as the attachment point for the ribs at the front of the body, thereby helping to create what is known as the ribcage.
Ribcage
The ribcage is formed by 12 pairs of ribs. Each pair of ribs is attached - one at each side - to the 12 thoracic vertebrae of the spine, which are the vertebrae to be found immediately below your neck. Each individual rib arcs around to the front of the chest where it connects to the sternum; the first seven ribs join directly to the sternum, the next 3 to each other, and the final 2 are ‘floating’ ribs as they do not join to anything at the front.
In this way, the 12 pairs of ribs, together with the sternum and the twelve vertebrae, create a sort of protective cage within which are found the lungs and the heart.
There are muscles which occupy the spaces between the 12 pairs of ribs, and these are called the intercostals. Just like the diaphragm, they are able to contract, thus having the ability to move the ribs and expand the ribcage.
By virtue of their attachment to the inside surface of the chest cavity, the lungs will be stretched and opened out by the expansion of the ribcage, in order to receive the inflow of air.
The mechanics of breathing
The cycle of breathing IN and breathing OUT is produced by the alternate expansion and deflation of the ribcage. It is quite wondrous and amazing to consider that this is a continuous, never-ending cycle until we take our last breath. We can’t begin to imagine how many breaths we take in a lifetime – most of them without our conscious awareness.
The inhalation is created by muscular contractions, and the exhalation is created by the release of those muscular contractions.
THE INBREATH / INHALATION / INSPIRATION
The inhalation occurs in the following manner:
(a) the diaphragm contracts, flattens out, and increases the depth of the chest cavity (thorax)
(b) the intercostal muscles contract, causing the sternum to lift forward and upwards (rather like the lifting of a bucket handle), and the ribcage to expand out sideways, forwards, and backwards.
The combination of diaphragm and ribcage movement enlarges the thorax and allows the lungs to expand and suck in the oxygen laden air.
THE OUTBREATH / EXHALATION / EXPIRATION
The act of exhalation is initiated by the release of muscular contraction:
(a) the diaphragm relaxes and resumes its natural domed form.
(b) the intercostal muscles relax, allowing the ribcage to return to its resting size and the sternum to sink back.
The previously enlarged chest cavity is reduced to its resting size, the lungs deflate and the air containing carbon dioxide is expelled.
Exhalation can be made more forceful by the use of the abdominal muscles. These can actively be engaged and pulled in when needed, by drawing the navel towards the spine. Try blowing out a candle from a distance and you will feel just how your abdominals have to work to pull the belly in and force the air out!
