How breathing works

How we breathe:* Air is warmed, moistened & filtered as it travels through the mouth and nasal passages.* It then passes through the trachea and one of the two bronchi into one of the lungs.* After passing into the many bronchioles, it finally arrives into some of the millions of tiny sacs called alveoli.* This is where gas exchange takes place - oxygen passes out of the air into the blood, and carbon dioxide passes out of the blood into the air in the alveoli.

When we inhale:* the intercostal muscles contract, expanding the ribcage.* the diaphragm contracts, pulling downwards to increase the volume of the chest.* pressure inside the chest is lowered and air is sucked into the lungs.

When we exhale:* the intercostal muscles relax, the ribcage drops inwards and downwards.* the diaphragm relaxes, moving back upwards, decreasing the volume of the chest.* pressure inside the chest increases and air is forced out.

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