I drink coffee every day. If you ask me why, I may answer that coffee can help me feel focused and energetic and this kind of feeling is terrific to me.
But how does coffee work ? Let me explain it in a simple way.
Our body needs energy every second from morning to night and we get the energy mostly from the process of breaking down high-energy substance called ATP. During the process a certain material is released (let's call it A). A has a certain receptor (let's call it A receptor). If A and A receptor get together, they can activates a series of reactions that can make our nersous system slow down, or make us feel sleepy. If you drink coffee, then there is a material in coffee get into your body, let's call it C. C's molecular structure is very similar to A, if C and A receptor get together, A has lost chance to work with A receptor to power down our neurons, so we feel sleep is gone.
But this kind of feeling is temporary, if our body find A receptor is not enough ,it will produce more for A to work, then you will feel sleepy again. If you still resist to rest, you will need more coffee, or more C to help. If you suddenly quit coffee, you will experience a terrible depressed mood. You may guess why, because there are still a lot of A receptor in your body, there are no more C , A can work overtime. But don't worry, in a few days, your body will know that you don't need so much A receptor , so they disappear, you will feel just as good as before.
Of course, we can not drink too much coffee. Too much C can raise our heart rate and blood pressure and contribute to anxiety.
我有每天喝咖啡的习惯。如果你问我为什么？我可能会回答：因为我喜欢咖啡带给我的精神集中，能量充沛的感觉。
但是咖啡为什么会有这样的作用呢？我试着简单解释一下。
我们的身体每时每刻都需要能量的支持，而我们大部分能量都来自体内高能物质ATP的分解过程。这一过程会产生物质A，物质A在人体内有特定的受体，我们叫它物质A受体。 如果物质A 与物质A受体 相结合，则会引发一系列的反应，最终是我们的神经系统兴奋度降低，也就是说让我们困倦。如果我们喝咖啡，那么咖啡中的物质C就会进入我们身体内。物质C的分子结构与物质A非常相似，当物质C与物质A受体结合后，物质A就不能再与物质A受体结合，从而不能让我们产生睡意。
但是这种清醒的感觉是暂时性的。一旦身体发现我们的物质A受体不够用，就会产生更多，从而物质A还是有机会与物质A受体结合，发挥其让我们休息的作用。如果此时你还是不想休息，那就得再来一杯咖啡。如果你哪一天突然戒掉咖啡，我就这么做过，结果是你会感觉极度的精神消沉，一蹶不振。不过也不用太担心，过几天之后，身体会了解到你不再需要那么多的物质A受体了，它们会自行消失，你也就会恢复如初了。只不过时不时还是会想念那种精力充沛的感觉。
当然，咖啡也不能喝太多，否则会引起心率加快，血压升高，心情焦虑等不良反应。
ps: 本文内容为原创，其中物质A 为：adenosine 腺苷 物质C 为 caffeine 咖啡因
