Alright. So in this video, we're going to be talking about how we can classify sensory receptors based on the type of stimulus that they detect or their modality. Using this classification method, we end up with 5 types of sensory receptors. First are mechanoreceptors, and these respond to mechanical force. For example, something like pressure or vibration would be mechanical forces. Then we have thermoreceptors, which I would bet, based on the name, you could guess that these are going to be responding to changes in temperature. It's important to note here that they respond to temperature changes, not just temperature itself. Next, we have photoreceptors. Those respond to light stimuli, and we have chemoreceptors which respond to chemicals. These could be chemicals in the air, for example, the molecules that we can smell. This could be something that we can taste. So food has molecules. We can taste those molecules. Right? This could also be coming from fluids in the body. For example, blood. Lastly, we have nociceptors, and nociceptors respond to damaging stimuli causing pain. These are sometimes called pain receptors. Nociceptors are a bit unique in that they can actually respond to different types of stimuli. Nociceptors can respond to temperature, they can respond to pressure, they can respond to chemicals. What is kind of special about them is that they're only going to respond to stimuli that are strong or excessive enough to cause damage or injury to our body. For example, if the heat is hot enough to burn us, if the cold is cold enough to damage our skin, if the chemical is irritating, if the pressure is excessive enough to cause harm, that is when those nociceptors will become active and send up signals to the brain and the brain will then perceive that stimuli as a painful one. Alright, so those are the 5 types of sensory receptors when we classify them by stimulus type, and I will see you guys in our next video. Bye-bye.
Sensory Receptor Classification by Modality - Online Tutor, Practice Problems & Exam Prep
Sensory receptors are classified into five types based on the stimuli they detect: mechanoreceptors respond to mechanical forces like pressure; thermoreceptors detect temperature changes; photoreceptors are sensitive to light; chemoreceptors respond to chemical stimuli, such as those involved in taste and smell; and nociceptors, or pain receptors, react to damaging stimuli, including extreme temperature, pressure, or chemicals. Understanding these receptors is crucial for grasping how organisms perceive their environment and respond to various stimuli.
Sensory Receptor Classification by Modality
Video transcript
Sensory Receptor Classification by Modality Example 1
Video transcript
Alright. So this example asks us if a receptor is rapidly adapting, it will respond maximally to a stimulus when it's first detected, and then the response will decrease if the stimulus is maintained. Which type of receptor is least likely to be rapidly adapting? To clarify, if a receptor is rapidly adapting, it occurs when it first detects a stimulus; it has its normal response. And then if that stimulus is maintained and constant and doesn't change, the receptor adapts and stops responding to it altogether. That's important for a couple of reasons:
- We have a ton of information being sent to our brain all the time. We don't want excessive and unnecessary information muddying everything up and getting sent up there as well. It just adds to the cognitive load that we don't need to add to.
- We don't want our receptors and our neurons to be constantly getting used. They would get exhausted. They need little breaks, so they don't want to be constantly firing if they don't need to.
Now, looking at our answer choices and thinking about this conceptually from an evolutionary perspective, I am immediately drawn to nociceptors because we don't actually want to adapt to pain signals. We might want to, but that's not actually safe. For example, if I broke my arm, if my receptors adapted quickly, what would happen is they would say, "Oh, ouch." Then they would adapt, and that pain signal would be gone. But then I could use my arm in a way that exacerbates the injury and hurts me even more. What you need is for those nociceptors to keep signaling and saying, "You are in pain." That way, you don't injure yourself further or exacerbate any injuries that you have. We don't want pain receptors to be rapidly adapting.
Looking at all these other ones to give you quick examples to show you that they are rapidly adapting, think about the mechanoreceptors that are picking up on pressure from your shirt, your pants, your socks, the chair that you're sitting on. You probably are not constantly aware of all of those things because you adapt to them. That's not necessary information as long as you are comfortable and safe. Same with thermoreceptors. As long as you're in an environment that is safe for humans to be in temperature-wise, you don't need constant information about the temperature of the space that you're in. And photoreceptors, we know, are very rapidly adapting. We've all walked from a dark room into a very bright space, and it kind of wacks you out for a second, but your eyes adapt very quickly to that as well. So, photoreceptors are also rapidly adapting. So our answer is night nociceptors. Those are the least likely to be rapidly adapting. So there you have it.
Which receptor type would you expect to find on the tongue, allowing us to taste?
Thermoreceptors.
Nociceptors.
Mechanoreceptors.
Chemoreceptors.
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