Blood pressure as a Vital Sign?!

Jess,
There are receptors that tell your veins/arteries to constrict when you go from a laying down position to a sitting/standing position. This occurs in order to push the blood back to your brain. In people who have vasovagal syncope, something is wrong with the receptors and instead of those veins constricting, they dilate, causing a lack of blood flow, thus a lack of oxygen to the brain, causing a fainting episode. This is the reason that the parasympathetic nervous system is activated instead of the sympathetic nervous system. I shall explain as briefly as possible - the central nervous system coordinates the reflex control of blood pressure. The main integrating centre is the medulla oblongata. [Because of the difficulty of studying neural net works in the brain we still know little about the nuclei, neurotransmitters, and inter neurons of the medullary cardiovascular control centre]. The Baroreceptor Reflex is the primary homeostatic control for blood pressure. The main function of the cardiovascular control centre is to maintain adequate blood flow to the brain and heart. Sensory input to this integrating centre comes from a variety of peripheral sensory receptors. Stretch receptors known as baroreceptors are located in the walls of the carotid arteries and aorta, where they can monitor blood flowing to the brain (carotid baroreceptors) and the body (aortic baroreceptors). When increased blood pressure in the arteries stretches the baroreceptor membrane, the firing rate of the membrane increases. If blood pressure falls, then the firing rate of the receptor decreases. Action potentials from the baroreceptors travel to the medullary cardiovascular control centre via sensory neurons. The cardiovascular control centre integrates the sensory input and initiates an appropriate response. The response of baroreceptor response is quite rapid. Changes take about two heart beats. Efferent output from the cardiovascular control centre is carried via both sympathetic and parasympathetic autonomic neurons. Peripheral resistance is under tonic sympathetic control, with increased sympathetic discharge causing vasoconstriction.


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It is extremely important to obtain an accurate diagnosis before trying to find a cure. Many diseases and conditions share common symptoms.


The information provided here should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions.


Hope this helps
matador 89