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Physical effects of stress

Video transcript
- Your heart is actually a lot like the engine in your car. It has valves, and it has pressurized chambers. And just like your engine is responsible for making the rest of the parts of your car run, your heart is responsible for the performance of a lot of the other organ functions in your body, by getting blood and nutrients to them. Your car is designed to accelerate pretty quickly every once in a while. For example, if you pull out in front of a car a little bit too late, you might need to slam on the pedal and rev up the engine to get your tail out of there. And similarly, your heart and blood vessels respond to acute stress by kicking into overdrive. So, your heart rate in the force of contraction increase, and your blood vessels tighten up to get blood, and those nutrients and that oxygen flowing around the body a little bit faster, in order to support your organs and tissues. And this is a really good thing if we're responding to an emergency. But just like we don't want to burn up the engine in our car by driving around at the max RPMs all the time, having our heart constantly operating in overdrive can be pretty damaging. And so I want to take a second, and I want to talk about the damaging effects of stress on our heart. And the first damaging effect of stress on the heart that I want to talk about, is related to increased blood pressure. So in response to the increased force of higher blood pressure during stress, the blood vessels distend a little bit, which means they get a little bit bigger, and so the blood vessels respond to this distension by building up a little bit more muscle, and by becoming a little bit more rigid. And that increased vessel rigidity requires then more force from the pump, more force from our heart to move blood through the vessels, because they're getting tighter, they're becoming more toned, and so it leads to a vicious cycle of elevating blood pressure that get higher and higher, and this can lead to a disease called hypertension, which I'll shorten as HTN. And that just refers to blood pressure that's too high. It's damagingly high. And one of the damaging effects of hypertension might be vascular disease. So, let me write that in here. Vascular disease. And what vascular disease refers to is disease of the blood vessels. And so, when blood constantly slams against our vessels, at higher than normal pressure, our veins and arteries experience little episodes of damage, and this leads to inflammation and plaque buildup. And that plaque is super attracted to things like fat and cholesterol, which end up sticking to these little spots, and narrowing our blood vessels. And one of the worst spots to experience this vascular disease, is in our coronary arteries. And when I say coronary arteries, I'm referring to the arteries that feed our actual heart tissue. And so, we call this kind of vascular disease coronary artery disease, or CAD for short. So, C-A-D. And when these little vessels get clogged up, the very organ that pumps oxygen and nutrients to our whole body, in the form of blood, is unable to keep working. It actually dies because it's not getting the oxygen and nutrients that it needs as a tissue. And so, when the heart tissue is un-nourished, and starts to die, we call that a heart attack. And without a working pump, the rest of our body is in real trouble. And it's not only our heart that can be damaged. Part of our metabolism, or the process of us breaking down food sources to get energy, that can be impacted negatively as well. So let me write down metabolism, so that we can create a category for these damaging effects. So when we take in extra nutrients, our body stores a lot of those extra nutrients up for later use. And we build up this complex backup of reserves, but during the fight or flight response, which gets initiated by stress, our body secretes little hormones like cortisol and glucagon. So it secretes these little hormones, like cortisol and glucagon. And glucagon helps, converts those glucose energy stores back into usable forms of energy, because we need that energy to either fight or to flee. And if the stress is just psychosocial, and we aren't actually running for our lives, we don't actually need all of this extra energy. And so that extra glucose can really exacerbate metabolic conditions, like diabetes, which is where we already have extra blood sugar. So, I'm gonna write down extra blood sugar. Because we don't actually need the energy, so this extra blood sugar is just floating around in our blood vessels. And it's especially serious, as rates of lifestyle based diabetes are skyrocketing, especially in Western cultures. And then on top of everything, the extra glucose can also contribute to the cardiovascular disease, which is what we were talking about before. So, too much blood sugar, because of overuse of our stress response, can be really damaging to us. And as if the damaging effects of stress on our metabolism and heart, weren't enough, it turns out that our reproductive abilities are also impeded by overstress. So let me write down reproductive. So reproductive. So, it turns out that, in girls, reproduction is a huge energy expense. And in terms of ovulation and uterine development, but even moreso at the prospect or pregnancy and fetal development. And so this exercise naturally gets shut down as a part of the acute stress response, as a part of that fight or flight response. And so, that's understandable, that we probably don't need to be making babies, when we're running away from dinosaurs, or when we are being chased by mutant zombies. But it turns out, that with chronic stress, which usually accompanies those psychosocial stressors, the hormones involved with pregnancy, like LH, luteinizing hormone, and FSH, follicle stimulating hormone, and subsequently, estrogen and progesterone, can become chronically inhibited, making it harder to release eggs or nurture their growth. And so girls' reproductive abilities can be really dampened by chronic stress. And boys experience a similar inhibition of sex hormones, namely in a reduction in testosterone. But the real interesting thing, though, is that testosterone levels are much less finicky, and don't depend on the precisely timed cycles that girls experience. So it's really actually hard to reduce them to the point of infertility. But, the big stress-induced problem in men, is actually erectile dysfunction, or impotency. Because, remember that when the sympathetic nervous system gets turned on, our peripheral blood vessels clamp down, so that we can keep more blood to our core, and that means that less blood is flowing to our appendages, including the penis. So, in fact, the majority of ED doctors, or erectile dysfunction doctor visits in our country, aren't related to organic impotency, but rather psychological induced impotency, often related to stress. And so, stress rears its ugly head in the heart, and it rears its ugly head in our metabolism, and it even damages and disrupts our reproductive capacity. But if that weren't enough, the negative effects of stress continue into our immune function. So, our immune function. And your immune system can be divided into two major categories. You have the innate system, and the adaptive system. Excuse me. The adaptive system is pretty complex. It's the one that involves all those specific white blood cells, antibodies that allow our body to remember bad stuff, and respond specifically. But on the other hand, the innate system is more basic and generic. And you can really think of it as the inflammation. Inflammation. In the short term, acute stress, that fight or flight kind of stress, can lead to overuse of the immune system. We turn on this inflammation too much. And when we have too much inflammation, we can start attacking good things in our body. And a good example of this is arthritis, when our joints become overly inflamed. So, we're attacking good things in our body. And so, that's what happens in the short term. We're overusing this inflammatory response. But chronic stress causes some different problems. If our bodies get conditioned to this chronic stress, we can actually stop activating the immune system response, appropriately. And our immune system can become suppressed. So now stress isn't necessarily making us sick, but it is making us more susceptible to illness. And it's making us more susceptible, because our body is suppressing this immune system, which seems to be acting too often. And so this has been shown in several experiments, including with animals and humans. So, and one example of this is decreased wound healing during stress. So research headed by Janice Kiecolt-Glaser showed a 40% slower healing rate for little puncture wounds administered to graduate students right before a major exam, compared to the same wounds applied during a summer vacation. And then, another study by Sheldon Cohen, showed increased susceptibility to illness during stress. They dropped a bit of virus into individuals' noses, and showed about a 20% increase in the development of colds for those that were reporting chronic life stressors. So while stress is designed to be a really good thing that helps get us out of danger, or helps us respond to challenges, it can really have some damaging effects on the physical aspect of our well-being.