The human respiratory system consists of anatomical structures that act as passageway for inhaled air. The air that we breathe in, flows through the nasal passage and travels through the pharynx,... More > larynx and the trachea. The trachea or the windpipe branches further into the right and left bronchial tubes. The bronchial tubes branch out into smaller branches that are called bronchioles. Clusters of tiny sacs, also referred to as alveolar sacs, are located at the end of the bronchioles. These sacs are surrounded by thin-walled capillaries. The oxygen from these tiny sacs is passed on into the capillaries, while carbon dioxide from the capillaries is released into the sacs, and is then exhaled out. While the air supplies us with the life-giving oxygen, there are unwanted environmental irritants, allergens or pathogens that we may inhale.
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