Welcome to episode 3 of Biology 2402 lab presentations on the adrenal glands. This is take 3 actually, because I keep screwing up. But in any case, let's look at these images. So there we have the adrenal gland on the left image is perched here on top of the kidneys, and that's just kind of a typical look for it in a model. And then you can see in the second image that it's been sectioned so that we can see The cortex, which is this outer region here, this sort of outer bit, and then the medulla, which is the inner triangle.
The capsule is sort of on this outside bit right there. In the dissected specimen, that was my phone, I was getting a text. Dissected specimen, you can see the kidney right here and the adrenal gland right there at the tip of the pointer, which makes this end up here, the head of the rat.
And I'll draw a little rat head. I drew his little head in the... Looks like in his rib cage somewhere, but whatever.
So there's the adrenal gland at the tip of the pointer. And then in the final image on the right, we see a microscope image with the capsule out here on the outer layer. And then the three zones, the glomerulosa on the outside, fasciculata in the middle, and reticularis here bordering the medulla. So if you want to remember GFR, that's how I always remember their sequence from the outside in.
And then the medulla sounds like middle, so pretty self-explanatory. We move on to some detail of the adrenal cortex. You see the three zones laid out there. Just try to remember that each zone produces mainly one class of hormone, and then there's pretty much just one or two major important hormones that are produced there.
There's more, but we're not going to get into them. So the glomerulosa produces this class of hormones called mineralocorticoids, and they are originally called that because they knew that they modulated sodium, which is a mineral concentration. But...
really what it should be called, they would be better named, we call them electrolyteocorticoids because it's really all electrolytes and then some water that follows. As you can see, the main hormone aldosterone targets the kidneys and causes the reabsorption of sodium and chloride. And then as a result of the sodium being reabsorbed from the urine or from the urine in progress, water will be reabsorbed also. Urinary systems are really built to get rid of nitrogenous waste, but we're terrestrial organisms, so we really want to save water.
So we produce aldosterone, which lets us reabsorb salt, which lets us reabsorb water. I also noticed that the aldosterone has the opposite effect on potassium, causing it to be secreted. The zona fasciculata is in the middle, and it produces glucocorticoids, and that sounds like sugar, which is why it was named that way. The main hormone in the class of...
glucocorticoids is cortisol and that name may sound familiar like cortisone or hydrocortisone because they're very similar molecules and you may be familiar with their function as anti-inflammatories which they do which so cortisol helps reduce inflammation if you don't want that inflammation the other main thing and why it's called a glucocorticoid is that it regulates blood sugar in this case it increases blood sugar levels not in the same way that that glucagon does which we will get to in the next video but in similar ways so it does this process called gluconeogenesis which has a its own definition built into the word right a lot of times you'll get to a word like this and you'll just kind of blur over it like right but don't try to break down these words mineralocorticoid glucocorticoid they tell you something about it Gluco is sugar, neo is new, and genesis is synthesis or beginning. So gluconeogenesis is sugar, new, make. Pretty easy, right, if you just constantly figure out what the word is.
So you can make sugar out of much smaller molecular components. You can build it anew as it is. Lastly is the zona reticularis, which produces a class of hormones called gonadocorticoids, and as you might infer, that. refers to your gonads or your testes and ovaries. Now, this layer, the reticularis, produces these hormones which act as androgens, but not just andro.
Andro is male, but precursors to both types of sex hormones. So if you have testes and you are releasing these gonadocorticoids, your testes can convert them into testosterone. Conversely, if you have ovaries, and your ovaries absorb these glucocorticoids, they will convert that into estrogen. So the adrenal gland, the cortex, specifically the reticularis, acts as a secondary source of your sex hormones, mostly produced by your gonads. Let's go to the medulla.
We have one region and two hormones. You've probably heard of them both in their original form and possibly in the medical term form, but adrenaline and noradrenaline is basically the same thing as saying epinephrine and norepinephrine. I've just gone to use epinephrine and norepinephrine. They both really are involved in your fight-or-flight response.
So if you've ever gotten real scared by something, like you wake up in the middle of the night and your imagination runs wild on you and you think there's... A guy hiding in your room, which is a true story for me. And it turned, you know, I got pumped up real quick, right? Heart rate goes up. I suddenly could see in the dark a lot better because my pupils were dilated.
I was breathing real hard. My skeletal muscle got a lot of blood. Turns out it was my jacket.
I put it on a chair and then forgot about it. And then when I woke up, I saw it. So don't worry. I'm fine. So blah, blah, blah.
What else? A couple of things about epinephrine. In addition is that when you exercise you get more adrenaline, which makes sense because you'd want the the same kind of effects that you get in a fight or flight response you find useful during exercise. So if you're going for a run or you're playing in a you know a game, a sporting event of some sort, you're going to get a little dose of epinephrine, especially if it makes you nervous, if you're scared before the match.
And speaking of scared... When you get that adrenaline dump, you get a lot of similar sort of physiological effects that you get when you experience fear, and it does help contribute to that sense of fear. You get like shakes and stuff.
Now, you may be ready to go at somebody also, right? But fear and fury are a fine line apart. Norepinephrine, largely overlapping in its overall effects. There's some differences physiologically, but we don't need to get into those.
So kind of the same effects. Now, if you chronically overproduce both of these, you can imagine what that does, right? I mean, if you're constantly pumping up your heart rate and vasoconstricting and dumping sugar into your blood, you're going to have a number of negative potential outcomes. You can see a short list of that there at the bottom.
All right. Hope that helps with your knowledge of the adrenal glands. Now, don't forget, like for this and for all of these PowerPoints, go to the the section videos and the videos over the models and study those images because you're going to see those images when it comes quiz time and test time