[MUSIC]. Hello students, welcome back. We're going to continue to talk about food. And I'm going to cover about enjoyment of food and how are we going to define whether the food tastes good or bad and what kind of parameter defines it. Now in fact, there are few things I want to talk about. First of all I want to talk about when the food comes to our body. What are they and how they are being perceived. And most of the time in fact these are the chemical that we take into our body. And in fact it's going to trigger a whole bunch of physiological response, which involve hormone. And they will regulate how we feel and whether we want to have more we don't want to have more. Of course all this food when they come front of it it is because how they look how they taste how they smell. So therefore this is a lot of sensory input and so for that we need to look how this sensory input is being perseived by us and how it's going to affect the quality of this food. And finally we want to talk about how this so called sensory specific satiety when we are constantly being stimulated by the same sense how do we feel. And whether we get tired of them or even though that we are, we love this kind of food but that we can continue to eat them again and again even though we are full. Now having that in mind I want to highlight a few other factors which is affecting how we perceive the quality of food. In fact a lot of time when we are eating the surrounding atmosphere makes a lot of difference. When you're in a very romantic restaurant or whether you're eating with your family. The mood, what kind of mood you are in, in fact affect how you taste the food. Sometimes the environment, whether you're outdoor, indoor. The dishes, when it is being put on the table whether they give it a very good name reminding you some of your memory. That is going to change your perception of the quality. And of course, sometimes we have personal experience and some of our responses to a particular flavor. That would all influence how we perceive food being good or bad. Now we can ask ourselves. Why do we want to have food, why do we want eating? as a biologist a lot of times we look at it because we want to have nutrients. We eat food, what kind of food. Vegetable fruits. These are sweet food and most of them when they were taken they will be converted into energy. And one type of the energy such as the mineral, amino acid, vitamin or glucose. These are all very important. They allows us to be incorporated to become having all these nutrients for us to mature to grow as an individual. But let me remind you, most of the time these days when we are eating. It's simply not because of all these calculations of how much nutrients are there. It's simply because we are hungry. And when you are hungry, you eat. And sometimes even though we are not hungry simply because we like to eat sometime that we likes so much that we want to keep on eating. This is called craving. Now that defines at a stage when or why we want to have food. Now let me come to the point of hunger. We say that a lot of time when you're hungry you want to eat food. But what is controlling it? As I pointed out earlier a lot of it is because of our biological response. It's because of our physiological states. Because we don't have enough energy. We want nutrients. So therefore we want to eat so that we can recapture some of this nutrients to allows us to function normally. But as I pointed out a lot of time is a psychological state, the social state. How we are interacting with the environment. All these affect us. So therefore I want you to start thinking about the reason why we eat is because of all this integral response in our brain. And that tells us that we want to eat something. And sometimes we enjoy eating not necessarily because we are eating the material the food by itself. It's because we like the feeling of anticipating that some food will be available very soon. Now so in the next section what I didn't tell you, is that I want to dissect this process one at a time we are going to address how the endocrine system. How our neuro-system, how we feel the sensory specific satiety when stimulated by same food again and again. Whether you feel full or you become tired of it. And finally why sometimes even though we are not hungry, we still want to eat. Why we have this craving behavior? So we'll address it in a moment.