Autonomic Nervous System - Anatomy & Physiology

()Map NERVOUS AND SPECIAL SENSES (Map)

Introduction

The peripheral nervous system found in most domestic species can be segregated into three sub-systems; the sensory system, the somatic motor system and the autonomic system. The autonomic system regulates the internal environment of the body and mobilises the body's resources during stressful situations. It controls gland cells, cardiac muscle cells and smooth muscle cells. Control of this nervous system is involuntary and regulation is via autonomic reflexes. The autonomic reflex arc system is very similar to that of the somatic motor system, i.e. there are sensory (afferent) nerve fibres, an information integration centre, motor (efferent) fibres and effector cells. Any levels of increased activity within the autonomic nervous system can result in both stimulation or inhibition of effector cells, although it is only the efferent part of the reflex arc that is actually considered autonomic.

The autonomic nervous system is made up of the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS). The SNS is activated during critical situations, such as fight or flight responses whilst the PNS is activated whilst at rest, such as during food digestion after eating.