Hello, and welcome to your special senses. Alright. Before we dive into the special senses, let's just remember that there are actually 2 types of senses, 2 general categories that we break things into. We have the general senses. These are things distributed throughout your body, and you've probably already learned about these, things like temperature, pain, pressure, things you can feel in your feet, your hands, your back, wherever. What we're talking about here are our special senses, and these are located in special sense organs. And all those special sense organs, they're in your head. Alright. We're going to say that there are 5 special sense organs, and we'll go through each one here. As we do, I want you to pay particular attention to the stimulus that's in the environment that these organs measure, and then how we perceive that stimulus. Because those two things aren't the same. And being able to link them, but also being able to tell what the difference between the two is, I think really helps us understand what special senses are doing and how they work. Alright. To see what I mean, let's start with vision. Now vision, the organ that does that, I bet you know, it's your eyes. And to illustrate that, we have a cross-section of an eyeball right here. What the eye is measuring is electromagnetic radiation or what we call light. But I think it's important to remember that there's nothing fundamentally different between light and other types of electromagnetic radiation, things like x-rays or radio waves. What allows us to call light light is that our eye is able to sense those wavelengths of electromagnetic radiation. And when it does, we see a couple of things. We see brightness which is the intensity of the radiation that's hitting our eyes, and color. And color is a measure of the wavelength of light that's actually coming into our eye. Alright. Next, let's talk about smell. Smell, also called olfaction, we use our olfactory epithelium to do that. And here we see someone smelling, we see a cross-section of the nasal cavity here and molecules are coming up into the nasal cavity. And we can see at the top there is the olfactory epithelium connected to the olfactory bulb inside the skull. And what smell is measuring is something about chemical properties, and when we measure those chemical properties, well, we perceive them as odors. Now kind of amazingly, we can distinguish something like a trillion different odors, which completely blows my mind. But what you're doing when you're doing that is you are identifying different molecules that are in the air or different combinations of molecules that are in the air. That brings us to our sense of taste, also called gustation, which in some ways is going to be similar to our sense of smell. For taste, we use our taste buds, and here we have a diagram of a tongue here because that's where the vast majority of our taste buds are located, and here we are also measuring the chemical properties. But here we're measuring chemical properties of things we put in our mouth or usually our food, but it's going to work very differently. Where we could distinguish a trillion different odors, here, we get 5 tastes. We get sweet, sour, salty, bitter, and umami. And umami, you may not be familiar with; it's a taste that sort of savory taste that's associated with sensing amino acids in your food. And all those tastes are giving us some sort of nutritional information about the food we're eating. Alright. Next, we have hearing. Hearing, we're going to use our ear and our cochlea. In our diagram here, we can see the outer ear, which works sort of like a funnel, into the actual sense organ, our cochlea. What we're measuring when we're using our hearing are pressure waves or vibrations in the air around us. And when we measure those pressure waves, we experience it as sound. But, again, it's just vibrations in the air. So I always think it's fun to think all those vibrations are actually hitting your entire body. The reason you don't feel them is that well, air doesn't exert a lot of pressure when it vibrates against your body. Your ear is just so fine-tuned and amplifies those pressure waves of those vibrations enough that you can experience them as sound. Our final sense that we're going to talk about is equilibrium. For equilibrium, we use our semicircular canals and our vestibule, and this is a structure that you can see here connected to the cochlear part of that inner ear. And with equilibrium, we measure movement and gravity. You can tell, even with your eyes closed, whether you're spinning, whether you're accelerating, whether you're upside down. Being able to do that is our sense of equilibrium. Okay. So those are the 5 organs and our 5 senses that we're going to talk about as our special senses. Again, going forward now, I want you to pay particular attention to the difference between the stimulus and how we perceive that stimulus. We'll practice that some more going forward, and I'll see you there.
15. The Special Senses
Introduction to Special Senses
Video duration:
5mRelated Videos
Related Practice
Introduction to Special Senses practice set
Problem sets built by lead tutorsExpert video explanations