 In recent videos, we've talked about what systolic and diastolic blood pressure are. We've talked quickly about how to measure it, but I just want to talk about where it actually comes from. If someone has high blood pressure, well, why do they have high blood pressure? Now, we do have what's known as primary hypertension. For the majority of people, we don't actually know the specific cause of their hypertension. But we know that your heart, my heart, everyone's heart, whether blood pressure is normal or not, is going to pump hard enough to move blood. So the blood pressure is the pressure your heart needs to produce in order to overcome. And here's the key word, peripheral resistance. So what are the things that can cause peripheral resistance that would need your heart to work harder and would need you to develop hypertension, high blood pressure, in order to survive and properly oxygenate your tissues? So there are multiple variables we're going to talk about here. Some are pretty common sense, but some are much more clinically relevant than others. This one's just cardiac output. Anything that's going to increase your cardiac output, hopefully remember that cardiac output is your heart rate times your stroke volume. So anything that's going to stimulate an increase in heart rate or stroke volume will cause your blood pressure to go up. This could be sympathetic stimulation like stress, something like that, exercise. These are things that will increase your cardiac output and will increase your blood pressure at the time. All right. That's your cardiac output. Next we have compliance. So think about your tubes. They're not pipes like the plumbing in your house. They're flexible elastic tubes, the blood vessels. So the more compliant they are, the more easily they can stretch when that wave of blood travels through them, the less of a spike in blood pressure you're going to see. So compliance, obviously when you're young, you have healthy, flexible blood vessels, especially the arteries, then this isn't going to be a huge issue. But as we get older, all of our blood vessels start to stiffen up. And that's why blood pressure goes up as you age. You could also make an argument. This would be where a lot of the spike in blood pressure comes from when you're lifting weights, when you're exercising. The strain that you put on your blood vessels and the contraction of the muscles can keep them from properly allowing blood to flow through them. So that's kind of a minor deal. But compliance, this to me is the number one reason that blood pressure starts to creep up as we go into old age. Next we have just blood volume. So if you have too little blood volume, your blood pressure will go down and too much volume, your blood pressure will go up. So you can get too much blood volume because of increased blood cell production, polysothemia, things like that. But normally I think of like hypovolemic shock. If someone's losing blood, their blood volume is going to drop and so is their blood pressure. And if they lose too much blood, their blood pressure can tank and they could possibly die. So when they would go into shock. So blood volume, I think that one makes the most sense. Next we have viscosity. So if we've talked about viscosity with blood, remember blood being about five times more viscous than water, viscosity is resistance to flow. So syrup is going to have a real high viscosity. I was going to say velocity. And so it flows slowly, water is going to have a lower one. So if you have a higher viscosity in your blood, that can definitely have an impact. Now again, conditions that are going to lead to too many blood cells. For some reason, if you have too many white blood cells, too many red blood cells, that could certainly do it. First one that pops into my head would be if you have high homocysteine levels. So homocysteine is this metabolic byproduct that can build up in your blood. And it is an independent risk factor for heart disease, meaning that if you have high homocysteine levels, you're at higher risk for heart disease and Alzheimer's and osteoporotic fractures, by the way, whether or not you have other risk factors. So that's the first one I think of with viscosity would be that. It's kind of a minor deal, though. All right, a couple more. We have blood vessel length and then we have blood vessel diameter. So the longer a blood vessel is, even if you have perfectly smooth blood vessels, every millimeter of the blood has to flow through them, there's going to be some friction and some resistance to flow. That's why your blood is warmer than the rest of your body because of this friction. So the longer your blood vessels are, the more resistance there's going to be and the more pressure is going to have to go up. This is why blood pressure goes up as you get larger. So the average person, maybe 150 pound male, will have somewhere in the neighborhood of 60,000 miles of blood vessels. Every 10 pounds you gain is going to add another two to four thousand miles of blood vessel, depending on if it's fat or muscle. So the more you weigh, the more cells you have, the more miles of blood vessels you need in order to take care of all that tissue. So gaining weight is going to put pressure on your heart because you now have more blood vessels. Losing weight is going to take pressure off of your heart because you now have less blood vessels. So that's vessel length and that's also, you know, think about just being taller. It's not about just gaining fat. People that are taller are going to have more pressure on their hearts. Go to a nursing home. You're going to see a lot of short people. The taller you are, the harder your heart has to work to move blood everywhere. That's blood vessel length. Blood vessel diameter. This is one I think we can control with stress versus mindfulness, these types of things. If you're under a lot of stress, your blood vessels are going to constrict and the blood pressure is going to go up. If you can relax, your blood vessels will dilate and blood pressure will go down. This is why meditation, yoga, watching funny movies, whatever works for you. If you can find ways to relax, your blood pressure should go down. And lastly, we have turbulence. So we mentioned that even perfectly smooth blood vessels are going to offer some resistance. Turbulence, if you have plaques lining, clumpy plaques lining the blood vessel walls, that's going to cause swirling and turbulence in your circulatory system that's going to also increase the blood pressure. So these are all the things I can think of that are going to lead to an increase in peripheral resistance or total peripheral resistance, which is then going to lead to a need for a higher blood pressure. So if you can control these things, some easier to control than others, then hopefully you can help keep your blood pressure down. All right, I hope this helps. Have a wonderful day. Be blessed.