The respiratory system and the mechanics of breathing

Editors Note: I originally wrote this as an essay for my Yoga teaching course, I wonder how many people have since found it and used elements of it for their own course work?  At the time of writing a lot of this seemed academic and too scientific for me to use on a daily basis.  Now many years later this same essay brings home to me how important this knowledge is.  Although on my yoga weekends I do not go into the technical terminology I do incorporate the factors that affect breathing and in turn our everyday health.

Mindful breathing, awareness of posture prove that good health is never more than a few breaths away.  Phil

The process in which air is drawn into the body.

Do you want to live forever? This is a question Dr Erik Peper (a leading doctor in helping people to breathe in the USA) asks all his patients, when he meets them.  His answer is always the same; ‘breathe in, breathe out, as long as you keep breathing in and out you can’t die’  Breathing is a process that all of us do without really thinking about it, but what does happen within the body as we draw air into the lungs?


The air enters the lungs (the bronchi) and then divides into smaller passageways called secondary bronchi, these repeatedly divide and become smaller bronchioles which contain no supporting cartilage. These thin walled respiratory bronchioles end in clusters of thin walled sacs called the alveoli.

The alveoli are in contact with air and blood across their thin walls, it is here that the exchange of gases by diffusion occurs.

A flap of cartilage called the epiglottis guards the opening to the larynx. This structure prevents food from entering the respiratory passage way and directs it to the esophagus.

By contrast the expiration of air from the body is a passive exercise involving the relaxation of the muscles used during inspiration

Factors that may affect breathing, including age, gender and posture

The basic characteristics of optimal breathing are that it should be diaphragmatic, nasal, deep, smooth, even, without sound and without pause.

In many ways the effects that age, gender, posture and illness have on our breathing can be interrelated with many of the factors crossing over into each category. However let us first look at age.


    1. Age: As people age, we see an increase in poor posture, with some people walking with a stoop. This can cause the restrictions in the ribcage resulting in poor expansion of the chest.

People who smoke are also more prone to chronic lung disorders such as emphysema and cancer of the lung.

    1. Gender: Generally men breathe more fully and lower in the abdomen where as women breath higher from their thorax. Tight fitting clothing can also effect breathing as can pregnancy. A pregnant woman may experience breathlessness due to her baby pressing on her diaphragm and ribcage. During pregnancy the volume of blood increases in a woman’s body, which can create breathlessness.
    1. Posture: Good posture is essential for optimal breathing. Unfit people generally have less stamina resulting in shallow breathing and a tendency to strain their muscles easier.

Posture can also be affected by the bad practices in the office and home. For example, people who work in front of a computer may sit for hours with their shoulders hunched over the keyboard. Equally, sitting slouched in front of the television will develop habits that will affect breathing

Stress can also affect posture and breathing. Anxiety before an important business presentation can result in shallow breathing and sometimes panic attacks and hyperventilation.

  1. Respiratory infections: The respiratory system is a prime candidate for infection. With its membrane-lined airways and delicate-walled alveoli it is in constant contact with airborne germs.

Viral infections such as colds, flu and sore throats are experienced by all of us at sometime, the most serious of these is pneumonia.

Pneumonia is an inflammation of the lungs. It makes the alveoli fill with mucus and fluid. This leads to the impairing of the gas exchange and as a result affects the functioning of the whole body.

Asthma is an obstructive lung disorder (as is emphysema). The problems that arise here are that air flow through the conducting airways is obstructed or limited.

With children and adolescents asthma is associated with allergic reactions to the sensitive bronchial tree, this can be from pollen, certain foods, dust, animal fur, exercise and the inhalation of cold air.

The airway obstruction can also be caused by the build up of mucus in the air passages, such as with chronic bronchitis. With emphysema this is a result of the disruption and expansion of the fibrous supporting tissue around the airway.

Smoking affects the whole body but its effects on the respiratory system are devastating. The toxic components of tobacco smoke kill millions of the tiny hairlike cilia lining the airways. This leads to the accumulation and stagnation of mucus, germs and inhaled debris. Smoking is the single most important reason for chronic bronchitis and emphysema. Lung cancer also affects one in ten heavy smokers (who smoke 20 or more cigarettes a day)


The Yoga Book by Stephen Sturgess (Element 1997) books

Yoga for Stress Relief by Swami Shivapremananda (Gaia books 1997) books

Yoga & health (May 1999)

Anatomy colouring workbook by I.Edward Alcamo, Ph.D. (Random House 1997) books

Dr Erik Pepper Ph.D. (quote taken from