Today's word is hemodynamics. I actually prefer the spelling haemodynamics, probably because my dad is Canadian, and I like to mix it up.
Fun fact: I wanted to name my kid something original with reversed letters, two dots over the "a", or that a and e that are connected, like it was written on the old encyclopaedias I grew up with. I was vetoed.
I still think every person should have to use the word "diphthong" when explaining their name to the substitute teacher.
So, hemodynamics (hemo=relating to blood or blood vessels, dynamics=mechanics, "the time evolution of physical processes") is the study of or the principles that dictate how blood moves through the body.
Haemodynamics are similar to hydrodynamics (the principles that dictates how water moves), only different. The main difference is that water is a Newtonian fluid - meaning that all parts of water are doing the same thing at any time. Blood is a non-Newtonian fluid, meaning different parts of blood do different things. This is because blood is made up of blood cells floating in liquid. The cells have a rigid shape (well, rigid for cells) while the liquid is more fluid.
The liquid is more fluid.
NOTE: Make sure you've read the previous blog (click here) before going any further!
In case you couldn't picture the difference between laminar and non-laminar (turbulent) flow, here's a picture:
We want to avoid turbulent flow because this type of current takes the blood cells and accelerates them into the walls (BAM!), creating a wounding that begins a cycle of inflammation, scabbing using cholesterol and calcium (which contribute to the hardening of the artery), which then begets more turbulent flow (and more wounding, and so on and so on.)
By now you are probably chomping at the bit to know what causes the turbulent flow, yes?
That's what I thought.
But before we look at the causes, you should know a little more fluid dynamics and recall a bit from your math and physics classes.
Picture a tube, like your garden hose for example.
You are probably familiar that you can change the velocity (the speed and direction it shoots out) of the water by changing the size of the tube, i.e. putting your finger over the end.
When you are washing your car (I hope there are still people out there washing their own cars in the driveway) and want the water to squirt out in order to be a bit more abrasive getting the soap off as well as cover a greater area, you instinctively know to put your fingers in a way that reduces the area and increases the velocity. Got it? This is a basic principle of hydrodynamics. Reducing the area of flow increases or changes the velocity.
Within the the arteries, non-laminar flow results in blood flowing all different directions. Patches of turbulence create "walls" that are similar to your finger over the opening of the hose. Even though water is a fluid, it can still act kind of like a solid in that it can change the direction of other fluids hitting it.
Are you with me?
To keep the blood flowing in a smooth fashion it is imperative to keep your blood laminar, man. We want grooovy, easy flowing blood. We want the Simon and Garfunkel of blood flow.
Once flow gets a bit bumpy it creates more and more turbulence, which in the long term creates plaque. But this plaque, see, is like a permanent finger over the hose so you get chronic turbulence wherever this plaque is located. Which then begets more plaque.
It's a vicious cycle.
So, back to causes of turbulent flow.
#1. Smoking. Smoking causes an instantaneous reaction (because you are basically preventing your lungs from getting any oxygen in that breath which freaks the body out) of stress chemicals that causes the blood vessels to open up instantly -- creating a change in the size of the tube, which then of course causes the blood to slosh around creating...you got it, turbulent flow.
#2. Stress. Stress itself causes stress hormones that do the same thing as #1. For more on stress and what it is physiologically, listed to my podcast here.
#3. Changes in Blood Vessel Geometry. There are natural changes in BVG in the body, where arteries branch off to travel different directions and in these places, the arterial walls have programs to deal with the change. The problem is when you change your blood vessel geometry arbitrarily, by adapting certain postures.
For example, the carotid arteries are oriented in a fairly vertical fashion,
but if you suffer from "computer head" or "cyclist's head" or "I'm anxious to get where I'm going head"
Another causes of turbulent flow is anything that changes the viscosity of your blood. Viscosity is the tackiness of a fluid. If your blood wears black socks everywhere than the viscosity is high.
No, just kidding.
Tackiness as in how much a fluid sticks to itself. Water has a lower viscosity than, say, honey or motor oil. When a fluid is more viscous it does not travel down a tube all together, but tends to clinging to itself creating...
Did you answer Turbulent Flow?
Did you say it outloud?
You are a nerd. You are reading a blog and you just said "turbulent flow" outloud, didn't you.
Good job. You are right!
So when it comes to the viscosity of your blood, there is one thing that changes it up pretty fast and that is...
#4. Blood Sugar. The higher your blood sugar, the more your blood is like syrup. Like the type of syrup Starbucks puts in your vanilla latte. Think about that next time you get a frappa-mocha-peppermint-dulce-venti-throat massage.
So, the moral of the story?
For cardiovascular health the items you need to address before running and jumping and medicating are:
1. Stop smoking. Really. Are you still doing that?
2. Start meditating or at least do all the other stress-reducing things that you already know you should be doing.
3. Align...everything. But start by pulling your head back (what we call "ramping up" in the A&W program) until your ear is over your shoulder like this:
This will make your standing work station EVEN BETTER.
4. Watch your blood sugar. But you already knew that too, didn't you.
When we talk about CV disease you will rarely hear about the mechanisms -- only the symptoms (like plaque). A correct, thorough prescription for prevention (or treatment) of CV disease should START with the items listed above.
Think about it.
Ok, off to feed my regular-named child.