NUR-631-D5Q1 Minimum of 300 words with at least 2 peer review reference in 6th edition APA style. The hypothalamic-pituitary system is the main controlling factor for normal endocrine function. What are some of the common ways for this finely balanced system to become unstable? Explain how the circadian rhythm is related to cortisol secretion from the adrenal cortex. What factors cause disturbances in this system? Purchase this Tutorial.