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INTRODUCTION

Chapter 5, Neurotransmission is a compilation of Chapter 8 Neurotransmission: The Autonomic and Somatic Motor Nervous Systems, and Chapter 14 Neurotransmission and the Central Nervous System in Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 12th Edition. An understanding of the material in these chapters will be helpful in following the material presented in this chapter. In addition to the material presented here, the 12th Edition includes:

  • A detailed discussion of the peripheral and central nervous systems (CNS)

  • An intricate discussion of the neurotransmitters in the peripheral and CNS, their synthesis, storage, mechanisms of release and termination of effect

  • Details of the cholinergic, adrenergic, and somatic nervous systems that are also addressed in Chapters 6 and 7 of this book

  • A detailed discussion of chemical transmission of impulses in the CNS

LEARNING OBJECTIVES

  • Understand the characteristics of the parasympathetic, sympathetic, and enteric nervous systems.

  • Understand the difference between the autonomic and somatic nervous systems.

  • Know the predominant transmitters at ganglionic sites in the parasympathetic and sympathetic nerves.

  • Know the transmitters and their target receptors in parasympathetic and sympathetic nervous system.

  • Know the effect that agonist and antagonists have at each target receptor.

  • Understand the blood-brain barrier (BBB).

  • Understand the intricacies of chemical transmission within the CNS and how the interaction of central neurons control the pharmacological effects of drugs acting in the brain.

DRUGS INCLUDED IN THIS CHAPTER

The pharmacology of specific drugs is not included in this chapter. The drugs presented in the cases are used as examples to illustrate various aspects of neurotransmission; the specific pharmacology of these drugs is presented in the subsequent chapters of this section.

CASE 5-1

A 47-year-old woman is given a drug to treat her overactive bladder. She is told that the drug is similar to atropine and that it will decrease her frequency of urination. She is cautioned to be aware of the possibility of dry eyes, dry mouth, blurred vision, constipation, drowsiness, dizziness, and confusion.

  1. What are the divisions of the peripheral autonomic nervous system that describe the diverse actions of this drug?

    The efferent nerves of the involuntary (autonomic) nervous system supply all innervated structures of the body except skeletal muscle, which is served by the somatic nerves (see Figures 5-1 and 5-2). The peripheral autonomic nervous system is composed of the sympathetic, parasympathetic, and enteric divisions (see Side Bar DIVISIONS OF THE PERIPHERAL AUTONOMIC NERVOUS SYSTEM).

  2. Why does this drug have such a broad constellation of side effects involving so many different organs?

    Atropine is a drug that blocks cholinergic muscarinic receptors located on the membranes of many effector organs (see Figure 5-1 and Table 5-1), and it blocks all the peripheral actions of acetylcholine, the parasympathetic neurotransmitter (see Chapter 6). Thus, it is easy to see why its side effects involve so ...

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