Introduction to Special Senses - Video Tutorials & Practice Problems

Special Senses

Hello and welcome to your special senses. All right, before we dive into the special senses, let's just remember that there's actually two types of senses to 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 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. All right, we're gonna say that there are five 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 are. I think really helps us understand what special senses are doing and how they work 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 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 things we see brightness, brightness 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. All right. 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 we, 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 s uh our sense of taste also called gustation, which in some ways is gonna be similar to our sense of smell. Uh for taste, we use our taste buds. And here we have a, 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 gonna work very differently where we could distinguish trillion different odors. Here, we get five tastes. We get sweet sour, salty, bitter and umami, 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 of those tastes are giving us some sort of nutritional information about the food we're eating. All right. Next we have hearing, hearing, we're gonna 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 or cochlea. What we're measuring when we're using our hearing is 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 because well, s 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 gonna 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 cochlea part of the inner ear. And with equilibrium, we measure movement and gravity. You are able to 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. OK. So those are the five organs and our five senses that we're gonna talk about as our special senses again going forward. Now, I want to pay, pay particular attention between 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.

Introduction to Special Senses Example 1

All right. For this example, we're gonna get kind of heady. It says for the following questions, carefully, consider the relationship between perceptions and the different stimuli that cause them. So we were previously just talking about how there are stimuli in the world, things like pressure waves or chemical properties or electromagnetic radiation. And then there are perceptions that we have things like sound, things like smell or taste, things like colors or sight. Those two things are different, right? These stimuli in the world only exist as our perception if someone is there to perceive it, if those things actually hit the receptor cells and they were perceived by the brain. So with that in mind, we're gonna ask these questions, hey, if a tree falls in the forest and no one is around, doesn't make a sound. All right, you've probably been asked this before, but now you can give a physiological answer. My sort of real strict answer to this question would be no, it makes pressure waves right? When that tree falls, certainly the air around it, there's gonna be vibrations, waves of pressure moving through it, but sound the sound of the tree only exists if it hits the receptors in somebody's ear and they perceive it as sound. All right. Our next question, if the light is on in the basement and no one is home, what color are the walls? Right. So, what would be your answer be to that? My really strict physiological answer would be no color. There would be, em, there would be electromagnetic radiation, specific wavelengths of electromagnetic radiation that if someone is there, they might see color. But if no one is there color doesn't exist, color only exists when it hits the retina in someone's eye and someone's brain perceives it. All right. Finally, if a hamburger is on the table and no one takes a bite, does it have a taste? All right. What would you say to that? All right. My real persnickety, very specific physiological answer would be no, it does not have a taste. It has chemical properties. When those chemicals dissolve in the saliva and hit your tongue, the gasses hit your nose. You're gonna smell that hamburger, you're gonna taste that hamburger. But just in the hamburger it doesn't have a taste. It has chemicals. Taste is a perception of those chemicals that are in the hamburger. All right. Now, questions like these, you're unlikely to see on a test. But I really think understanding this distinction between the stimulus, the receptor that measures that stimulus and how we experience that stimulus as a perception in our brain really helps you understand special senses, a lot, lot better.

What is the difference between special senses and general senses?

• A. Special senses use action potentials, while general senses use graded potentials.
• B. Special senses are located in special sense organs, while general senses are distributed throughout the body.
• C. General senses include sight, taste, and equilibrium; special senses include pressure, temperature, and pain.
• D. The receptors for general senses are receptor cells, while special senses use modified nerve endings.

Which of the following correctly matches the sense to the type of stimulus it measures in the environment?

• A. Electromagnetic radiation: Smell.
• B. Pressure waves traveling through a fluid: Hearing.
• C. Chemical properties of gasses dissolved in a liquid: Equilibrium.
• D. Movement and gravity: Sight.