你每天都早晚刷牙嗎？是不是清潔后，口腔就會干凈了呢？事實可不是這樣，我們的口腔中住著大批的“居民”呢，一起來認(rèn)識一下吧！
YOUR MOUTH IS A JUNGLE!
For the bacteria, fungi, protozoa, and viruses inhabiting our mouths, life is
a piece of cake, or whatever else we have eaten. What we lunch on, they munch
on.
In fact, our mouths are ecosystems for them, as the weather forecast remains
the same at 95? F, unless we are ill, the level of humidity at 100%, and the
guaranteed a free meal on, actually in, the mouth is unconditional. They select
their own living quarters, with some preferring life between the teeth, others
preferring the space between the gums and the teeth, others preferring the roof
of the mouth, and yet others preferring the cracks in the front or in the back
of the tongue. They do, however, work for this luxurious lifestyle, by
performing such tasks as eating each other, fending off bad species of bacteria,
etc., manufacturing different products, and eating the food that becomes lodged
in parts of our mouths.
The only harmful species of bacteria inhabiting our mouths is Streptococcus
mutants, the cavity causing bacteria. Microbiologists believe that initially,
this bacteria was our friend, and played a useful role in our mouths, just as
the other species of bacteria do. As man progressed down the evolutionary
timeline and began refining raw sugar, Streptococcus mutants became the enemy.
This species thrives upon refined sugar and, as a part of its digestive process,
converts sugar into acid.
Before man began refining sugar, the bicarbonate ions in our saliva possessed
the ability to counteract the acid it produced. With the arrival of refined
sugar on the scene, and Streptococcus mutants' insatiable appetite for it, acid
production increased to the point where the saliva could no longer counteract
it. The excess acid produced erodes our teeth, causes cavities, and subsequent
visits to the dentist.
The more than 100 species of bacteria, and hundreds of species of fungi,
protozoa, and viruses that have taken up residence in our mouths is difficult to
fathom. Microbiologists estimate that, in addition to these known species, there
are up to 500 other living, breathing organisms inhabiting our mouths, although
only 50 have been identified and named. The sheer number of these creatures is
astronomical, considering the fact that our mouths contain more bacteria than
the entire world's population, and the fact that our bodies house approximately
one trillion bacteria.
What is a person to do about these squatters? Nothing. Our bodies provide an
ecosystem for them and, in return, they defend us from the invasion of bad
bacteria, viruses, fungi, and protozoa, with the exception of Streptococcus
mutants and a couple of other undesirable species.
Our dentists' advice to brush and to floss our teeth on a regular basis
should be taken, as doing so helps to maintain healthy levels of these creatures
from between 1,000 to 100,000 per tooth.
Enjoy your next meal... they certainly will!
（來源：coolquiz.com 英語點津Annabel編輯）
