So here we have an example problem that says, imagine you're a pathogen trying to enter a human body via the skin on a person's sole of the feet. Which layers of the epidermis do you have to get through and in what order? And so, to solve this problem we need to recall the memory tool for remembering the layers of the epidermis in order from deep to superficial. And recall that memory tool is beautiful skin glows like crystals. And so, notice here, I've drawn a sketch of the memory tool.
Beautiful skin glows like crystals, which again, organizes these layers from deep to superficial. And notice that the first letter of each of these words is going to represent the layers of the epidermis. And so, you can see the layers are stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. Now, what we also need to realize is that the stratum lucidum is only going to be present in thick skin, and it's absent in thin skin. And so, we need to realize that we're entering the skin on a person's sole of the feet.
And recall from our last lesson video that the sole of the feet is going to have thick skin. And so that means that the stratum lucidum is going to be present in this journey that the pathogen is taking. And so, let's imagine again that we are this pathogen and let's represent the pathogen as this red dot. We know that we're going to start outside of the body, and that means that we're going to start on the superficial side. And we want to enter into the body which means that we're going to need to cross through all of these layers to get deeper and deeper into the body.
And so that means that in terms of the layers of the epidermis that we have to get through and the order that we need to go through them, it's going to be all 5 of the layers in this particular order from superficial to deep. Starting with the stratum corneum, then the stratum lucidum, then the stratum granulosum, then the stratum spinosum, and then finally entering through the stratum basale. And that is what's going to allow us to penetrate through the epidermis into deeper layers of the skin. And so, this here concludes this example problem. Hopefully, you can see the value in this memory tool.
Beautiful skin glows like crystals, and hopefully that can help you solve some of the problems. So, I'll see you all in our next video.