 Hey everybody, Dr. O. Before we start talking about individual hormones, we have to talk about how hormones work and what do they actually do, what kind of impacts they have on the body. So here's the endocrine system. These are all your key endocrine glands. Their other tissues make endocrine secretions as well, make hormones. But I think of them as the keys, right? I think that your endocrine glands basically just spew keys into the circulatory system, right, into your body. So the role they have depends on where they end up with the locks. And that's a very important word when you're looking at hormones is target receptors. So if the thyroid gland is just going to dump thyroid hormone into your bloodstream, it's going to impact every cell that receives blood, but it's only going to actually dock on and have a direct impact on cells that have target receptors for thyroid hormone. So if the hormones are the keys, then target receptors are going to be locks. And here we see an example of a membrane receptor. So if that happens and this cell is going to be impacted by a hormone, what kind of things can we expect to happen? Generally hormones are going to change, maybe they're going to have this cell sort of synthesize and secrete a new product, they're going to activate enzymes, maybe they'll turn enzymes off to deactivate them, change the growth rate of the cell, maybe change the membrane permeability of the cell, or just impact protein synthesis and have the cell start making more proteins. So these are some of the many ways that hormones work, but they're only going to impact cells that have those target receptors. That's the key. Now a single hormone can have multiple effects in a cell. So thyroid hormone would be a great example there. Thyroid hormone can dock on the mitochondria and change how the mitochondria behaves, but it can also dock right on the DNA and change gene expression as well. So one hormone can have multiple impacts even in a single cell. What are some other factors then that are going to impact how the system works? I think a big one is inflammation. So if someone has a lot of inflammation, if they're inflamed because they're sick or lots of other reasons, inflammation does have an impact on hormones. Hormones are still being released, but the signal isn't getting through as easily. So if someone is inflamed, it might lead to leptom resistance or these types of things where there are hormones out there or there's like cortisol resistance too, where there are hormones out there, but in this inflammatory environment, your cells aren't receiving the signal properly. So inflammation would be an important one. Probably the most important terms to talk about though, and we talk about how hormones are, the impact of hormones can be changed, would be up regulation and down regulation. If you don't have enough of a hormone, if there's not a lot of it, then your cells are going to actually build more receptors. The receptors they have are going to be more active. So up regulation means if there's not a lot of hormones, the cells are really going to be paying attention. So you might see that as hormones start to decline in some sort of disease state. Down regulation is even more important though. If you're exposed to a whole lot of a hormone, then your cells will actually have less cell receptors and the ones that are there are going to become less sensitive. This is what happens when a cell becomes resistant. And the reason this is so important is because of primarily insulin resistance. So if a type 2 diabetic develops insulin resistance because their cells have been exposed to so much insulin because of poor diet or whatever, and that the cells will stop listening. I've seen people, I've had patients with insulin levels 10 or 11 times higher than normal, but their blood sugar is still high. So there's tons of insulin around, but the cells aren't receiving the message. So that would be an example of down regulation. Maybe later we'll talk about other ones too, like the ones I mentioned, leptin resistance and cortisol resistance. But in the United States, there are now 100 million diabetic or pre-diabetic people. So the down regulation caused, or that is the cause of insulin resistance is the key one to remember. Okay, what else about that? So the hormones also are going to impact how other hormones works. There's a few terms here I will want you to know. The first is what's called permissive effects. So there are hormones that actually allow other hormones to do their job. Probably the most important example here would be thyroid hormones. Like a lot of your reproductive hormones are actually, they need the permission of thyroid hormone to work. So that makes sense, I guess. If you have enough metabolic capacity to reproduce, then you'll get to go ahead. I think insulin would be an example as well, but I won't go through all the examples. But permissive effect means one hormone that enables another hormone to do its job. Synergistic effect, I always think with synergy, this 1 plus 1 equals 3, right? Where two hormones actually work way better together than they would either of them on their own. I think the reproductive hormones are going to be the key ones here. You've got the hormones released from the pituitary gland like follicle stimulating hormone and luteinizing hormone are going to work with the hormones produced by the gonads, testosterone, estrogen, et cetera, in order for follicles to mature in females, sperm to be produced, et cetera. So that would be a synergistic effect where hormones are working together. Another good example there would be antidiuretic hormone and aldosterone. I know we'll cover all these later, but they both are going to lead to an increased absorption of water at the kidneys. So they would have a synergistic effect. Lastly would be antagonistic effect where one hormone has the opposite effect of another. So the most famous example here would be insulin, which brings your blood sugar down by storing glucose and using glucose and glucagon, which brings your blood sugar up by releasing glycogen. So that is the permissive effect, synergistic effect and antagonistic effect. I think that's plenty for one video, but these are some of just the basic rules we have to understand before we dive into individual hormones. So I hope this helps. Have a wonderful day. Be blessed.