Introducing hormones

This chapter provides an overview of hormones, which constitute a range of different compounds, including peptides and steroids. Oversimplification of information about hormones can lead to some misleading ideas. For example, not all hormones are slow acting as is often assumed. The endocrine and nervous systems are closely connected, and hormones are released by a range of different tissues in the body, not just the 'classical' endocrine organs. Steroid hormones are all made from cholesterol by a process called steroidogenesis, while peptide hormones are made just like any other protein. The effects of hormones are all as a result of the hormone binding to its receptor. These receptors are found in target tissues, and their cellular location depends on the chemical type of hormone. The chapter then looks at negative feedback control, which is the most effective means of regulating blood levels of hormones and their effects.