感冒時，很多人都會出現鼻塞的症狀，而鼻塞為什麼會使我們那麼難受呢?
眾所周知，我們有左右兩個肺臟，但可能很少人知道，每一側肺臟都是由其同側相應的鼻孔控制的。
因此如果一個鼻孔堵塞，兩側的肺就會產生競爭，讓人覺得難受、呼吸不暢。不僅如此，專關家認為兩個鼻孔還能使呼吸運動更有效，進而推進整個機體的新陳代謝。用兩個鼻孔透氣使得每一個鼻孔可以輪換稍事休息，如果只用一個鼻孔透氣，3小時就會感到疲勞。
兩個鼻孔的生理結構有助於睡眠。在8小時以上的睡眠中如果保持一種睡姿不變，由於重力作用與站姿時相比發生了變化，一側的鼻孔通常會閉塞。
因此，我們用兩個鼻孔透氣可以睡得更放鬆。由於睡眠中人對氧氣的需求量減少，即使一個鼻孔暫時不通，只有另一個呼吸也不會造成呼吸不暢。
今天我們就一起了解一下兩個鼻孔的重要性吧。
Take a Look in the mirror and ask yourself this: why do I have two nostrils. Two eyes, sure. Two ears, ok. But why two nostrils? Wouldn't one, big nostril do just as well?
Actually, no. First, one giant nostril would look really weird. And second, although they may look identical, each nostril actually smells a bit differently. For most people, nostrils take turns swelling and shrinking, meaning that at any given moment the rate at which a nostril inhales is not equal.
Let's say you're taking a walk and stop to sniff a rose. Your swollen nostril inhales the tiny, microscopic particles released by the rose at a relatively slower pace than the normal nostril, which inhales at a normal clip. This is important since chemicals that enter your nose and create smell, including rose particles, come in two basic types: those that dissolve slowly and those that dissolve more quickly.
In order for slow-dissolving rose chemicals to really work they have to enter the nose at a leisurely pace and kind of settle down. If they're rushed in on a fast stream of air too many pass right through the nose and don't contribute to that unique, rosy smell. The rose chemicals that dissolve quickly, meanwhile, like to charge in and spread out fast in order to really pack a punch. Since they inhale at different speeds, your nostrils allow both kinds of rose chemicals to do their thing.
So a rose may be a rose, but in order to really smell one you need two nostrils. One big one just won't do.
