2010-05-30

[文摘] 為什麼人要有二個鼻孔?


正好看到朋友提到這樣的問題,為什麼人要有二個鼻孔?

這個問題還蠻有趣的,人有些器官是對稱的,但對稱的構造是有特別的功用,就從臉部的構造來說,二個眼睛提供雙眼視覺,可以分辨3D環境的遠近,二個耳朵可以分辨聲音來源的方向,那為什麼人要有二個鼻孔而不是像一個嘴巴只有一個開口就好? (原因大概不是為了流鼻水的時候可以塞一個鼻孔還有另一個可以呼吸…)

竟然在有朋友找到這樣的研究,解釋人為什麼要有二個鼻孔,以下文章連結出自Nature,研究指出,在二個鼻孔同時呼吸的情況下,其實氣流的強度是不同的,正常情況下二個鼻孔呼吸的強度是每隔一段時間會左右互換 ,這呼吸氣流的強度,則會影響其嗅覺的不同,在氣流比較強的情況下,大分子的"味道"不容易被聞到,如此一來,其實二個鼻孔所"聞"到的氣味是不同的。

Olfaction: The world smells different to each nostril

Noam Sobel1, Rehan M. Khan2, Amnon Saltman3, Edith V. Sullivan1,4 & John D. E. Gabrieli1,2

Abstract
The flow of air is greater into one nostril than into the other because there is a slight turbinate swelling in one1, 2, 3. The nostril that takes in more air switches from the left to the right one and back again every few hours4, 5, 6, but the effect of this switching on the sense of smell has been unclear7, 8. Here we show that this difference in airflow between the nostrils causes each nostril to be optimally sensitized to different odorants, so that each nostril conveys a slightly different olfactory image to the brain.

連結:http://www.nature.com/nature/journal/v402/n6757/full/402035a0.html

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