Читать книгу Asthma-Free Naturally: Everything you need to know about taking control of your asthma - Patrick McKeown - Страница 10

Before you commence breathing retraining, it is important for you to have a basic understanding of the roles played by the respiratory system and carbon dioxide in your body. Your respiratory system consists of the parts of your body used for the delivery of oxygen from the atmosphere to your cells and tissues, and for transporting the carbon dioxide produced in your tissues back into the atmosphere. If cells and tissues are to function properly – if you are to live – your body needs the atmosphere’s oxygen. Your nose, mouth, pharynx, larynx, trachea, bronchi and lungs are all part of your respiratory system.

Part of your airways is your nose and mouth. Through them, air enters your body and flows down a flexible tube called the trachea. This tube eventually divides into two branches called bronchi: one branch enters the left lung and the other branch enters the right. Within your lungs, the bronchi further subdivide into an estimated twenty-five smaller branches called bronchioles. The bronchioles run into alveolar ducts and at the end are small air sacs called alveoli.

Look at it another way. Imagine an upside-down tree. The trachea is the trunk; at the top of the trunk are the two large branches of the bronchi. From each of these large branches grow the smaller branches of the bronchioles. At the end of each smaller branch are the ‘leaves’, the round balloon-shaped sacs called alveoli.

When you breathe in, air enters through your nose or mouth and flows into the trachea, the bronchi, bronchioles and eventually alveoli. The grape-like alveoli – after which they are named – are surrounded by tiny blood channels called capillaries. Oxygen enters the blood by passing through a very thin barrier between the capillaries and air sacs. It is then carried by what is called haemoglobin within

Our lungs

A close-up of Alveoli (air sacs)

the blood to tissues and cells. There are approximately three hundred million alveoli in the lungs, each of which is surrounded by tiny blood vessels.

To put this huge number in context, think of Wimbledon and imagine a tennis court. The area of contact between your alveoli and blood capillaries is equivalent to the size of a tennis court; as you can imagine, this massive area provides scope for an efficient transfer of oxygen from the air to your blood. Carbon dioxide is produced as an end product of the process of breaking down the fats and carbohydrates that you eat, and this gas is brought by your venous blood vessels to your lungs where the excess is exhaled. Crucially, part of your body’s quotient of carbon dioxide is retained when you exhale, and correct breathing results in the required amount of carbon dioxide being retained in your lungs.

There are two main aspects to the way you breathe. Your rate is the number of breaths you take in one minute and your volume is the amount of air drawn into your lungs. Although the two are separate, one generally influences the other.

The volume of air we inhale and exhale is measured in litres, and measurements are usually taken over one minute. In conventional medicine, the accepted number of breaths a healthy person takes in one minute is ten to twelve, with each breath drawing in a volume of 500 millilitres. In a full minute, this provides the body with a total volume of five to six litres. If a person is breathing at a higher rate of twenty breaths, for example, then the volume will also be higher, and vice-versa. To visualise this amount of air, imagine how much air would be contained in a two-litre soft drink bottle.