Considers the process of neurotransmission, especially chemicals used in the brain and elsewhere to carry signals from nerve terminals to the structures they innervate. Focuses on monoamine transmitters (acetylcholine; serotonin; dopamine and norepinephrine); also examines amino acid and peptide transmitters and neuromodulators like adenosine. Macromolecules that mediate neurotransmitter synthesis, release, inactivation, and receptor-mediated actions are discussed, as well as factors that regulate their activity and the second-messenger systems they control.

Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Explain how the binding of a ligand initiates signal transduction throughout a cell
Recognize the role of phosphorylation in the transmission of intracellular signals
Evaluate the role of second messengers in signal transmission