嗅觉、味觉、触觉、视觉、和听觉：每一种感觉都给带给我们有关周围世界的不一样的信息。



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选材／校对／翻译：hqj5715
Smell, taste, touch, sight, and hearing: each one brings us a different kind of information about the world around us. But the oldest sense of all may be one evolved millions of years ago to help early multi-cellular organisms detect gravity. We still have that organ in the form of a small bowl lined with tiny hairs inside each ear. Each bowl holds a thick fluid and tiny calcium stones a tenth the diameter of a human hair. When your head is upright, the fluid and stones cover the hairs in the bottom of the bowl. If you tilt your head, the stones and fluid slosh in that direction, bending the tiny hairs as they go. Those tiny hairs are connected to nerve cells, which tell the brain which hairs are being bent and in what direction. With that information, the brain can tell whether your head is upright, leaning to one side, or hanging upside down. In fact, this system is so sensitive that it can tell if your head is tilted even one degree to the side. The system works more automatically than our other senses, so as long as it's working, we don't even notice it: we just feel a little off balance and our muscles automatically set us right again. A bad ear infection can affect this tiny system and that's why earaches are sometimes accompanied by a loss of balance.
嗅觉、味觉、触觉、视觉、和听觉：每一种感觉都给带给我们有关周围世界的不一样的信息。但是这一最古老的感觉在几十万年前便帮助最早的多细胞有机物发现重力的存在。 我们现在仍有这样的器官，以具有细小的毛发的小碗形状存在于我们的耳朵中。每一个碗状的器官含有高密度的液体和只有人体头发直径十分之一的细小钙化骨。当你的头部直立时，液体和骨覆盖于存在碗状器官底部的毛发。如果你倾斜你的头部，液体也骨便朝那个方向移动，使细小的毛发向同一方向弯曲。 这些细小的毛发与神经细胞相连，使大脑能够感知哪些毛发发生弯曲及朝哪个方向弯曲。利用这些信息，大脑便可以判断你的头部是否为直立、歪向一边或者悬挂的状态。事实上，这一系统十分的敏感以至于可以辨别出头部朝一侧仅仅一度的倾斜。 相对于其他的感觉，这一系统要自动化的多，因此在其工作时，我们甚至都不能认识的到：我们只能感觉有一点不平衡时我们的肌肉便自动使我们再一次的直立。严重的耳目感染能够影响这一系统，这也是为什么耳朵疼痛的病人经常会伴有失衡的原因。