Dr. Dawn-Elise Snipes explains how the HPA axis controls your stress response, from the initial trigger through the cascade of hormones like adrenaline and cortisol. When it stays stuck in overdrive, you get cortisol resistance, inflammation, sleep problems, and a disrupted gut. Recovery depends on the vagus nerve bringing you back down.
Hey there, everyone, and welcome to this video that answers the question, what is the HPA axis? And why should I care? I'm your host, Dr. Donnelly Snipes. The HPA axis is the clinical way of referring to the stress response. The HPA axis is the master control center of that stress response system. Now, if you've watched some of my other videos, you know that the HPA axis has a couple of buddies. The HPG axis axis, which is the hypothalamic, pituitary, gonadal, and the HPT axis, the hypothalamic, pituitary, thyroid axes, and all three of those axes work together in tandem in order to modulate your stress response. But the HPA axis is the master control center, and it helps regulate your adrenal glands, your cortisol levels, your thyroid hormones, your goddle or your sex hormones like estrogen, progesterone, testosterone and oxytocin, your blood sugar levels, your immune system, your neurotransmitters, and more. Your HPA axis has its grimy little mitts in just about everything. So how does it work? Well, the nervous system, your sensory organs, your eyes, your ears, your nose are, is regularly taking in information from the environment and comparing it to what it thinks it knows. So it compares it to schema based on prior learning. And if the prior experience with whatever that is was not good, then it triggers the stress response. If it searches for a schema for prior learning and there's nothing there, that also triggers the stress response. However, you know, it is possible that the sensory information is taken in like you see a bunny rabbit and your brain consults the schema and goes, oh, bunny rabbits, not a threat, no problem, ignore it. So the brain is regularly sorting the information that comes in into what I kind of refer to as three piles. The no threat, the mild to moderate threat, that's going to make you a little bit edgy or irritated, and then the extreme threat, that's when you're going to have your, you know, flood of emotions. When the information indicates a possible threat, the HPA axis is triggered. And in all my other videos, I've talked about how the HPA axis is akin to a smoke alarm. When a smoke alarm goes off, it does not mean that there is a fire, it means that there might be a fire. Your HPA axis is the same way when it is triggered. It means based on prior learning, based on other experiences, there might be a threat in the present, but it's not saying there is a threat in the present. However, when that HPA axis is triggered. The smart your little body's smoke alarm goes off. Chemicals called glutamate, norepinephrine, adrenaline, and thyroxin are released. All of these are excitatory neurochemicals. They're designed to help you have energy and focus. Your body also releases a bunch of blood sugar so you have a quick source of energy in order to assess if there's a threat and if there is, to respond to it. Endorphins, your body's natural painkillers, are released to suppress pain in the event that there's a threat. You don't want to be hampered by being in pain. So during that initial stress response, endorphins are released. Your sex hormones, your gonadal hormones are altered. Because if there's a threat, it's not the time to procreate, okay? It's time to fight or flee. Now, estrogen and testosterone have a lot more functions than just libido, which is why I say they're altered. They aren't completely suppressed, and your immune system is suppressed. Now, that's important to recognize that under stress, when the HPA axis is activated, your body is saying, we need to fight or flee. We'll work on repairing later. Right now, focus all your energy on fight or flee. When the person determines that the threat is no longer there, the vagus nerve and the HPA axis work together to sort of shut down the stress response and trigger the relaxation response, repair response, the rest, and digest response. There's lots of Rs that get triggered in a healthy system. This is when the immune system jumps into action and assesses and repairs the damage. So when cortisol goes down, unfortunately, inflammation may go up. Your inflammatory cytokines are released to go on patrol and see if there's anything that needs to be repaired. If not, then all of the repair guys come back to station. When there is HPA axis dysregulation, which means the HPA axis stays activated for too long. Then cortisol loses its ability to suppress inflammation. Your body says, okay, we have been on this fight for too long, and we need to send out the crews to find out if there's damage, because we can't keep incurring injuries without repairing them. So no longer is cortisol able to suppress inflammation, no longer are you not feeling pain. So you start experiencing systemic inflammation. The libido stays down, sleep is disrupted. If the threat response system is on. Just like if you had a smoke alarm that that was going off right outside your bedroom door all night. Long, you're not probably going to sleep very well. The immune system is in overdrive. All of your inflammatory cytokines are going around looking for damage. But because cortisol can't suppress inflammation, you've got random systemic inflammation that is happening. Mood becomes disregulated. The brain says, okay, we can't be this stressed out all the time. We can't run this hot for this long. So I'm going to make it less, I'm going to make the nervous system less sensitive. So things that normally would have gone into that mildly irritating pile don't really bother you that much anymore. You just ain't got the energy to deal with it. You ain't got the energy to care. However, when there is something that goes into that extreme threat pile, guess what? You have a tsunami of stress hormones that are dumped on it because your body is already operating from a vulnerable state. If you're already vulnerable, if you're already kind of edgy, then it doesn't take much to trigger that extreme reaction. The nervous system stays on high alert, becomes hypervigilant. Your gut microbiome is altered and it's important to recognize that the microbiome, those are the bacteria, the microbes in the gut that break down your food into the component parts and then help reassemble them into things like neurotransmitters and tissues and hormones. So when you're under stress, a different crew of workers is called in because you're making different neurochemicals and different hormones in different amounts. Most simplified way that I can put it. And neurotransmitter and hormone balances are altered as a result. You're not going to be making GABA and serotonin and some of those feel good chemicals. Right now you're going to be making glutamate and adrenaline and thyroxine. For a more in depth look at the HPA axis and mood, watch allceus.com HPA axis allceus.com HPA those will give you some long form videos that really go in depth to explain everything that we've just talked about. If you need CEUs, you can find CEUs for this topic@Allce.com HPA CEU.
