The human body

A question - if the human body has so much feed back systems then how can doctors think they can find what is wrong with a person. We have many feed back systems in the human body. A doctor has to be taught the different feed back systmes if they was to figure out what is wrong with a person. They run test for individual systems like the heart etc yet there are many controlls that effect the heart. For instance - person can take a drop of blood and check for blood sugar content but many things seem to effect the amount of sugar in the blood at any one time. A person can be infected and the reading will be high yet the Kidneys are not the problem only the problem is maybe the kidneys may be working harder to try and clean the blood and of course the readings are higher.Exercise seems to have a lot of control as to what kind of readings will the individual get.Yet what does a doctor give the person with the high readings but pills to counter act the readings in blood sugar yet that is not the answer.As I said in starting this article - the body is made up of many feedback systems and there ought to be study made of the different paths. This reminds me of a radar set that I worked on once- They would run individual cabinet outputs and say they worked but that was not the answer as the output of one cabinet would be fed into another and the pulses would add or even subtract to order to get certain output to make it work. The out puts of one cabinet would even shape the input of the pulse to set up a proper I will call match. Yet the individual output could not be use to trouble shoot what was wrong with the radar set. the human body works the same way and consequently the individual tests would not in many cases tell what is wrong with a person. It is like ring around the rosy - the question becomes where is the Rosy and or the Rose. It is too bad I can not write straight forward but I guess I do not know enough but am learning. Don