Autonomic Drugs – BCSE Study Guide

Overview and Clinical Importance

The autonomic nervous system (ANS) is a critical regulatory system that controls involuntary physiological processes including heart rate, blood pressure, respiration, digestion, and glandular secretions. Understanding autonomic pharmacology is essential for veterinary practice because these drugs are used daily in sedation, anesthesia, emergency medicine, and treatment of various organ system disorders.

The ANS has two main divisions: the sympathetic nervous system (SNS), which mediates the "fight or flight" response, and the parasympathetic nervous system (PNS), which controls "rest and digest" functions. A balance between these divisions maintains homeostasis, and drugs can be used to modulate this balance therapeutically.

Autonomic Nervous System Fundamentals

Organization and Neurotransmitters

The ANS consists of a two-neuron chain from the central nervous system to target organs. The preganglionic neuron has its cell body in the CNS, while the postganglionic neuron has its cell body in an autonomic ganglion. Understanding the neurotransmitters and receptors at each synapse is fundamental to predicting drug effects.