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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 meters

  • the 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.

  • But some of these invaders may get past the mucociliary escalator

  • into the lungs, where they meet the alveoli.

  • Because alveoli serve as critical exchange points

  • between the blood and air from the outside world,

  • they have their own specialized types of white blood cells, or macrophages,

  • which defend against foreign organisms by enveloping and eating them.

  • When pathogens enter the lungs, the macrophages work to destroy them.

  • The immune system releases additional white blood cells in the alveoli to help.

  • As these immune cells fight the pathogens, they generate inflammation

  • and fluid as a by-product of the inflammation.

  • When this fluid builds up,

  • it makes gas exchange inside the alveoli much more difficult.

  • As the level of carbon dioxide in the bloodstream begins to rise,

  • the body breathes more quickly to try to clear it out and get more oxygen in.

  • This rapid breathing is one of the most common symptoms of pneumonia.

  • The body also tries to force the fluid out of the alveoli through coughing.

  • Determining the cause of pneumonia can be difficult,

  • but once it is established, doctors can prescribe antibiotics,

  • which may include either antibacterial or antiviral treatments.

  • Treatment with antibiotics helps the body get the infection under control.

  • As the pathogen is cleared out,

  • the body gradually expels or absorbs fluid and dead cells.

  • The worst symptoms typically fade out in about a week,

  • though full recovery may take as long as a month.

  • Otherwise healthy adults can often manage pneumonia at home.

  • But for some groups, pneumonia can be a lot more severe,

  • requiring hospitalization and oxygen, artificial ventilation,

  • or other supportive measures while the body fights the infection.

  • Smoking damages the cilia,

  • making them less able to clear even the normal amount of mucus and secretions,

  • let alone the increased volume associated with pneumonia.

  • Genetic and autoimmune disorders

  • can make someone more susceptible to pathogens that can cause pneumonia.

  • Young children and the elderly also have impaired clearance

  • and weaker immune systems.

  • And if someone has viral pneumonia,

  • their risk of bacterial respiratory infection is higher.

  • Many of the deaths from pneumonia are due to lack of access to healthcare.

  • But sometimes, even with appropriate care,

  • the body enters a sustained fight against the infection it can't maintain,

  • activating inflammatory pathways throughout the body,

  • not just in the lungs.

  • This is actually a protective mechanism,

  • but after too long in this state organs start shutting down,

  • causing shock and sometimes death.

  • So how can we prevent pneumonia?

  • Eating well and getting enough sleep and exercise

  • helps your body fight off infections.

  • Vaccines can protect against common pneumonia-causing pathogens,

  • while washing your hands regularly helps prevent the spread of these pathogens

  • and protect those most vulnerable to severe pneumonia.

Every time you breathe in, air travels down the trachea,

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Why is pneumonia so dangerous? - Eve Gaus and Vanessa Ruiz

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    林宜悉 に公開 2020 年 11 月 30 日
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