The document summarizes key concepts about mammalian hormones. It lists the three major chemical groups that most hormones belong to: amines, peptides, and steroids. It explains that hormones can either promote or inhibit actions in target organs or many organs. Hormonal secretion is controlled by the hypothalamus and can occur in response to the presence of specific substances, other hormones, or nervous stimulation from the autonomic nervous system.

5. Amines Amine group Adrenaline Thyroxine

6. Peptides Peptide Insulin Glucagon

7. Steroids