肺炎为何如此危险?Why is pneumonia so dangerous - Eve Gaus and Vanessa Ruiz

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Every time you breathe in, air travels down the trachea, through a series of channels called bronchi, and finally reaches little clusters of air sacs called alveoli.

There are some 600 million alveoli in the lungs, adding up to a surface area of roughly 75 square metersthe size of a tennis court.

These tiny sacs, only one cell thick, facilitate a crucial exchange: allowing oxygen from the air we breathe into the bloodstream and clearing out carbon dioxide.

Pneumonia wreaks havoc on this exchange.

Pneumonia is an infection of the alveoli that causes them to fill with fluid.

There are many different kinds of pathogens that can cause pneumonia.

The most common ones are viruses or bacteria.

These microscopic invaders enter the body via droplets either in the air we breathe, or when we touch our eyes, noses, or mouths after touching a contaminated surface.

Then, they face the respiratory tract's first-line defense: the mucociliary escalator.

The mucociliary escalator consists of mucus that traps invaders and tiny hairs called cilia that carry the mucus toward the mouth, where it can be coughed out.

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