Lecture 23 Summary: Introduction to biochemical signaling

As an introduction to the subject of biochemical signaling, we consider the utilization by higher animals of circulating molecules called hormones as regulators of metabolism and other organismal processes. The pancreas is an organ that is responsible for the production of glucagon and insulin, two principal metabolic regulators. The adrenal glands secrete the catecholamine hormones epinephrine and norepinephrine. (13: 405-412)

Hormones are extracellular signaling molecules, and these secretions of an organ or tissue type can exert long-range influence on the activities of the cells of other organs and tissues. The bigger part of the story for our purposes will be the transduction of the hormone signal into cells of the target tissue. Typically, the hormone binds to a receptor molecule embedded in the cell membranes of the target. The binding event then triggers a series of intracellular responses. These signal transduction pathways can be quite complex, and understanding their mechanisms, effects, and integration is a large and challenging area of research. We'll begin learning about the major systems of cellular signal transduction systems by considering a class of receptors called receptor tyrosine kinases. (13: 412b-416m)

Learning objectives (VVP3e, p.406 margin)

• Understand the general functions of hormones produced by the pancreas, adrenal cortex, and adrenal medulla.
• Understand that a hormone's effects depend on the presence of a specific cellular receptor, and the receptor's sensitivity to agonists and antagonists.
• Understand that hormone binding induces changes in the receptor, such as dimerization.

Page updated 07-24-2010

References