This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Down regulation of hormone means ? \nSelect and explain. \nA. Decreased secretion of hormone, B. Decreased affinity to receptors, C. Defective regulation in secretion, D. Regulation by low concentration of hormone', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Decreased affinity to receptors Down regulation is a mechanism in which a hormone decrease the number or affinity of its receptors in target tissues. Down-regulation may occur by decreasing the synthesis of new receptors, by increasing the degradation of existing receptors or by inactivating receptors. The purpose of down-regulation is to reduce the sensitivity of the target tissue when hormone levels are high for an extended period of time.", 'role': 'assistant'}]