Our nose, the gatekeeper of breathing
Of course, the nose plays a crucial role in breathing: if we breathe well through the nose, only purified, humidified and optimally heated air will reach our lungs. Air enters the nose from the nostrils and begins its journey in the human body through two nasal cavities, which are similar to canals with banks covered with mucus. Perhaps that doesn’t paint a pleasant picture, but mucus actually has an important function here, because it humidifies the air and retains any microbes and dust that otherwise would risk “illegally” entering our body. Meanwhile, the dense network of blood capillaries in the walls of the nasal cavities warm up the air, which is subsequently filtered by an array of small hairs.
Down the funnel of the larynx
Once past the nasal cavities, the humidified and filtered air enters the pharynx, an organ that connects with both the oesophagus and the larynx in its final part. Air and food can coexist peacefully in the pharynx, which is also part of the digestive system. After this “hybrid zone”, air moves towards the larynx: an organ shaped like an inverted funnel, which houses the vocal cords and is made up of 5 pieces of cartilage, one of which forms the epiglottis and another the so-called “Adam’s apple”. After passing through the larynx, air moves into the trachea, which looks like a flexible tube formed by C-shaped cartilaginous rings and is over 10 centimetres long. The trachea is located in front of the oesophagus and its internal walls are covered by cilia that move upwards, in order to eliminate any impurities or foreign bodies.
From the lungs to the air we breathe out
Air ends its journey under the trachea, dividing between 2 branches known as bronchi. Each of these 2 bronchi ends in a microscopic cavity full of blood vessels. Finally, from the bronchi air passes into the lungs, consisting of 300 million alveoli. The right lung is larger and divides into 3 lobes, while the left one has only 2 lobes to leave room for the tip of the heart. The oxygen contained in the air is directed towards the mitochondria, which are cells’ energy engines. What is left of the initial air, carbon dioxide, water and waste products, pass from the cells to the blood, which will carry them to the alveoli to be then eliminated by exhaling.