So, as we know, our skin consists of several layers and these different types of layers create an impermeable membrane that prevents the physical movement of pathogens into our body. On top of that, our skin also contains glands which secrete fatty acids. And when we create a layer of fatty acid on our skin we essentially create an inhospitable environment on which most bacteria cannot actually grow on and live on. Now, let's go into our mouth. Inside our mouth we essentially produce a special type of proteolytic enzyme known as a lysosome. And the lysosome is also produced by our eyes.