气味或气味是人类和其他动物通过嗅觉或嗅觉感知的挥发性化合物。气味也被称为香气或香味,并且(如果它们令人不愉快的话)是臭气,炖肉和臭味。产生气味的分子类型称为芳香化合物或气味剂。这些化合物很小,分子量小于300道尔顿,并且由于它们的高蒸气压而容易分散在空气中。嗅觉可以检测出异味浓度极低的气味。具有嗅觉的生物通过称为嗅觉受体(OR)细胞的特殊感觉神经元检测分子。在人类中,这些细胞聚集在鼻腔后部。每个感觉神经元都具有延伸到空气中的纤毛。在纤毛上,有与芳香化合物结合的受体蛋白质。当发生结合时,化学刺激在神经元中启动电信号,该信号将信息传递给嗅觉神经,嗅觉神经将信号传递到大脑中的嗅球。嗅球是边缘系统的一部分,也与情绪有关。一个人可以识别气味并将其与情绪体验联系起来,但可能无法识别气味的特定成分。这是因为大脑并不解释单一化合物或其相对浓度,而是整个化合物的混合物。研究人员估计人类可以区分10,000到1万亿种不同的气味。气味检测有一个阈值限制。一定数量的分子需要结合嗅觉受体来刺激信号。单一芳香化合物可能能够结合几种不同受体中的任何一种。跨膜受体蛋白是金属蛋白,可能涉及铜,锌和锰离子。

美国宾夕法尼亚大学化学Essay代写:香气化合物及其气味

An odor or odour is a volatile chemical compound that humans and other animals perceive via the sense of smell or olfaction. Odors are also known as aromas or fragrances and (if they are unpleasant) as reeks, stenches, and stinks. The type of molecule that produces an odor is called an aroma compound or an odorant. These compounds are small, with molecular weights less than 300 Daltons, and are readily dispersed in air due to their high vapor pressure. The sense of smell can detect odors are extremely low concentrations. Organisms that have a sense of smell detect molecules by special sensory neurons called olfactory receptor (OR) cells. In humans these cells are clustered at the back of the nasal cavity. Each sensory neuron has cilia that extend into the air. On the cilia, there are receptor proteins that bind to aroma compounds. When binding occurs, the chemical stimulus initiates an electric signal in the neuron, which transmits the information to the olfactory nerve, which carries the signal to the olfactory bulb in the brain. The olfactory bulb is part of the limbic system, which is also associated with emotions. A person may recognize an odor and relate it to an emotional experience, yet might be unable to identify the specific components of a scent. This is because the brain doesn’t interpret single compounds or their relative concentrations, but the mix of compounds as a whole. Researchers estimate humans can distinguish between 10,000 and one trillion different odors. There is a threshold limit for odor detection. A certain number of molecules need to bind olfactory receptors to stimulate a signal. A single aroma compound may be capable of binding to any of several different receptors. The transmembrane receptor proteins are metalloproteins, probably involving copper, zinc, and perhaps manganese ions.

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