<prompt> Which of the following is not mediated through negative feed back mechanism -BPGH formationThrombus formationACTH release  <response>: Ans. is c i.e.. Thrombus formation Negative feedback systemo Most control systems in the body act by negative feedback.o In this if some factor become excessive, a control system initates negative feedback, which consist of series of changes that return the factor towards a certain mean value,o Examples are: ACTH secretion Aldosterone - Ksecretion Glucose regulation GH secretion BP regulation Positive feedback systemo There are very few situations in which the body operates on the basis positive feed back.o This is because positive feedback does not lead to stability but instability, and in some cases, can cause death will discussed in next explanation.o However, in some situations body operates in positive feedback manner, for example : Clotting blood Ca2 entry into sarcoplasmic reticulum LH surge during ovulationAction potential Shock Parturition 