Turning air to life – The respiratory system

Breathing is a process we seldom ponder over. But knowing how it works might help us appreciate the subtle genius of this oxygenation machine in our intricate body

What are you doing now? Reading?

Chances are, you’re breathing. (we hope you are, at least!)

Being able to breathe freely is one of the most taken for granted abilities we have. You could say that about other bodily functions as they’re all part of one unit. However, breathing is what sustains us from the moment we are born to our dying breathe.

In some cultures and religious traditions, it is believed that God or a divine being breathed into man when he was first created. Thus, sometimes, people describe living as having merely “borrowed breathe”.

In the 13th century, Arab physician Ibn Al-Nafis became the first person to describe the breathing process, in other words, the pulmonary circulation. The understanding of what the lung is and how it works has helped doctors to treat and manage the various complications that could develop in this vital organ.

If you have read up till this paragraph in one minute, you would have breathed in altogether six litres of air. In a day, we breathe 20,000 times. If we live up to 70, that would be about 600 million breaths! It’s hard work to breathe effortlessly.

The respiratory system

The lungs are but a part of our respiratory system which also consists of our nose, throat, voice box, and diaphragm.

The ribcage covers our lungs and the diaphragm muscle at the bottom of the lungs.

How do we breathe?

Our nose inhales the air which passes through it, filtered by the cilia which are hair-like particles that protect the nose from dust and other unwanted particles. Of course, we could breathe in through our mouths as well.

The passageway from these two breathing orifices joins at the back of our throats to form the pharynx. The pharynx carries food and air. It is divided into two segments – the oesophagus for food to pass through, and the trachea for air to go through.

There are protective cartilage “rings” semi-wrapped around the trachea which protects it and keeps it strong.

Then, there’s a flap called the epiglottis which covers the trachea (air only) passage when we swallow. It helps stop food and liquid from entering into the lungs.

The voice box, or larynx is found at the top of the trachea. It stretches down about 12cm from the trachea.

The trachea is 2cm to 3cm but after the voice box, it extends down 12cm into the lungs. It also contains tiny hairs which keep out dust and other particles from entering the lungs.

The trachea splits off into two smaller branches called the bronchi which connects the trachea to our lungs.

Our “oxygen tanks”

The lungs aren’t exactly twins. You’ll notice the difference soon.

The right lung is made out of three lobes divided into the right superior (topmost lobe), right middle and right inferior (bottom lobe) while the left lung has two lobes, the left superior and left inferior. This means the left lung is slightly smaller than the right. Why is that so? This is to make space for the heart positioned between the two lungs.

Continuing from the bronchi, it travels further into the lungs to split off into tinier branches called bronchioles. At the end of these bronchioles, there are air sacs that look like budding grapes. This is the alveoli, not to be confused with an Italian dumpling. Within the grape-like structure are air sacs. The entire alveoli is surrounded by networks of tiny blood vessels (blood capillaries).

The oxygen-carbon dioxide exchange

As red blood cells flow through the capillaries, the oxygen that enters through the air passageway of the lungs gets infused into the red blood cells. This causes them to be oxygenated. As they are filled with oxygen, carbon dioxide molecules get released back into the alveolus (the individual air sac that altogether makes the grape-like alveoli). The carbon dioxide then travels out of the body through the trachea and out of the nose and mouth.


The diaphragm is the divider between the chest cavity and the bottom abdominal cavity. This dome-shaped muscle assists with the inhalation and exhalation process. When we inhale, the diaphragm stretches out to help the lung have more space. When we exhale, it expands upwards to push the air out.

What happens when we exercise

When energy is exerted in the instance when we run or indulge in physical activities, the body needs more oxygen to fuel our muscles. Our breathes becomes more rapid and we breathe more deeply as a result.

The cells in our bodies then consumes more oxygen. The oxygen-carbon dioxide exchange within our lungs would have to exert itself in order increase the supply of oxygen.

When we exercise more, the capacity in our chest cavity would also expand. This allows our body to increase the volume of air it inhales.

Ultimately, more capillaries would also increase around the air sac in order to increase the body’s efficiency in transforming air into oxygen and carbon dioxide gasses.

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