1. What does the endocrine system consist of?: Answer Glands that secrete hormones 2. How doesthe endocrine system maintain homeostasis?: Answer By using hormonesas chemical messengers which are secreted in response to changes in internal environment 3. How are hormones classified?: Answer By structure (steroid vs. nonsteroid), source,and primary effects 4. Steroids: Answer Lipids that enter the cell nucleus to initiate transcription directly 5. Peptide (nonsteroid): Answer Needs a secondary messenger system to activate transcription in the nucleus 6. What is the endocrine system controlled by?: Answer A negative feedback systemwhere the endocrine and nervous systems work together to regulate metabolic activities 7. What causes excess hormone levels?: Answer Tumors (usually benign) produce highlevels 8. What are the results of excretion impairment by the liver or kidneys?: