Alterations of Sympathetic Vascular Tone in Arteries

We are jumping into a very complex and in-depth discussion of something that may be a little confusing so I will try to go slow and not go off on a tangent. As we start the most important thing we need to talk about is a little bit of the anatomy and how the body works. I'm sure you know that tone and texture of the inside of your arteries and vein are very important. The veins are on the lower pressure side and the arteries are on the high pressure side. The veins are very distensible so they can act to store large amounts of blood in a time of relaxation and contract and push the blood into the arterial side when the heart needs to increase cardiac output. The arteries are relaxed or constricted  based certain physiological needs to that tissue. If a tissue needs more blood it constricts arteries to other areas that do not need blood at that certain time. Hormones also play important roll in this system as well, hormones like cortisol causes an activation of the sympathetic system. When the sympathetic are active under either hormonal or neural control the arteries increases their muscle tone to slow the blood flow from organs which are not used in a period of distress or intense activity. This is how the system should work properly.

The way this system works in a lot of people is problematic, first people are stressed, stress causes the release of cortisol, the release of cortisol causes the increase of the sympathetic nerve system systemically. The activation of the sympathetic nervous system causes a decrease of lumen diameter, thus increasing overall blood pressure. You see how this is a slippery slope of how the body works. I will say that arterial lumen pressure is inversely proportional to diameter, meaning as the lumen gets small pressure goes up. There are two ways the body can increase blood pressure, increase the cardiac output, and decrease artery diameter. The only way the heart can increase cardiac output or work is to do two things, first increase the force of contraction of the ventricles and increase the amount of blood pumped by the ventricles. So if you are always running on your sympathetic system invariably you will have a higher blood pressure, but how do we fix this?

With the sympathetic nervous system on overall you must break the brain-body communication so to speak we must reboot the system but how? How about we preform something that going to overload the whole system to restart, something call afferent barrage, now I'm using afferent barrage very loosely. When I use this term it is in the context of applying numerous sensory stimuli to a certain area in the body. It's possible to reset the system from sensory input. When spinal manipulation is applied to a segment, it's creating many synaptic connection, which could reset the system, of course more evidence is needed to fully valid the effectiveness. The afferent input could in turn lower the force of heart contraction, reduce the amount of blood pumped for contraction, and dilate the arterial lumen. There have been studies that show spinal manipulation could decrease blood pressure but they have some decrease of bias. However, it's exciting to see the possibility of an external stimuli causing a sympathetic change.