The cardiovascular system is depressed - reducing heart rate and cardiac output, and routing blood flow toward visceral beds. The parasympathetic nervous system in contrast, increases the activity of the abdominal viscera.

There is an overall increase in CNS stimulation, and respiratory drive is increased. In the cardiovascular system, increased inotropic and chronotropic drive lead to increased cardiac output and blood flow is routed toward vital organs and skeletal muscle. In general the sympathetic nervous system can be thought of as preparing the body for “fight or flight”. These two divisions differ in both structure and function as will be seen later. The “effector limb” of the ANS is subdivided in to 2 separate divisions – the sympathetic, and parasympathetic nervous systems.

These postganglionic fibres mediate the desired response at the effector organ. The efferent limb of neuronal autonomic reflexes consists of specific primary autonomic nerves that synapse in autonomic ganglia, with secondary or “postganglionic” fibres. Ii) The Central Nervous System – for example the “vaso-vagal response” to impending cannulation in a needle-phobic patient. I) The Autonomic Nervous System - for example the tachycardia in response to hypotension, mediated by baroreceptors, or. The afferent input to the reflex arc varies and can be from: In general, ANS effects are involuntary, relatively rapid, neuronal reflexes. The ANS can thus be thought of as the regulatory system, that partly or wholly controls most of the body’s organ systems and homeostatic mechanisms. These functions are controlled subconsciously, with a degree of automaticity, by a branch of the nervous system - The Autonomic Nervous system (ANS). For example, we don’t have to remember to digest our food after a meal, or sweat when too warm. What is the Autonomic Nervous System? Many bodily functions proceed without any conscious supervision from our central nervous system (CNS). What types of receptors are there in the autonomic nervous system? What are the transmitter substances in the autonomic nervous system?ĥ. How do parasympathetic nerves get from the CNS to end organs?Ĥ. How do sympathetic nerves get from the CNS to the end organs?ģ. What is the autonomic nervous system and what are its functions?Ģ. It is therefore essential that the anaesthetist should have a basic understanding of its structure and function.īefore reading the tutorial, see what you already know about this subject by answering the following questions:ġ. Many anaesthetic procedures and drugs used in anaesthetic practice have a direct influence on the autonomic nervous system. Department of Anaesthesia, Hope Hospital, Salford M6 8HD, UK.Į mail: Autonomic Nervous System: Basic anatomy and physiology

Secrete adrenaline