Control Mechanism:a) Negative Feedback- observed in the body wherein certain conditions in the body is above or below normal and the feedback tries to bring back the body back to normal. (eg. high BP, it will bring it back to normal); counteract existing mechanism and bring the condition back to normal; term used for neuronial activity If it involves the activity of the endocrine system (hormonal control)- endocrine axis driven feedback (eg. Hormone in blood decreases, the effect will be greater than normal, it will decrease the hormone back to normal) CHANGE IN THE LEVEL OF HORMONE IN THE BLOOD WHICH AFFECTS THE ACTIVITY OF THE ENDOCRINE SYSTEM BRINGING THE CONDITION BACK TO NORMALb) Modified Negative Feedback (Physiologic Response Driven Feedback) change in the level of a certain non-hormonal agent in blood and alter activity of the endocrine system bringing it to normal. NOT LEVEL OF HORMONE (eg. Level of blood glucose produced by beta cell of islets of langerhans changing endocrine cell) *take note: whatever is that agent that affects activity of the endocrine cell, level of that agent in the blood is controlled by the affected endocrine cell. eg. Level of blood glucose is affected by the secretory product of the beta cell of islets of langerhans; level of calcium in the blood produced by parathyroid hormonec) Positive Feedback control-compared to negative feedback, (-) feedback, you oppose the condition, in (+) feedback, it allows existing condition to continue or even exaggerate the condition. (eg. pregnancy- progressive release of hormone to make the baby grow until labor. hormone oxytocin); for neural: bleeding conditions during injury. Body will respond by lessening the blood loss. Progressions is vasoconstrictionactivate platelets- activate clotting factor) ALLOW THE ACTIVITY TO PROGRESS. d) Feed Forward- observed anticipatory responses of body to a certain condition once exposed to a certain condition (eg. Response of digestive system when person smells/ sees food; beginning of exercise, there is initial hyperventilation and increase in heart rate)e) Up Regulation (Supersensitization) changes in level of certain structures present in the cell affected by hormones and even the agents. (eg. growth hormones, DM type I and II)Whether it is a neurotransmitter or a hormone, what is needed for them to effectively exert their effects on the cell? - Receptors Condition wherein there is decreased level of neurotransmitters or hormones in the blood, lesser effect of the agent in the body or targeted cell. The cell affected or target cell will try to increase the number of receptors responding to the hormone or the neurotransmitter to maintain normal condition. To maintain normal effect of the transmitter or hormone f) Down Regulation (Desensitization) observed in excess level of the hormone or neurotransmitter. If sumobra, the effect of the cell will be more than normal. The affected cell will decrease the number of receptors to lessen the effect of the agent of the cell.