ANS .The autonomic nervous system (ANS ) coordinates cardiovascular, respiratory, digestive, urinary and reproductive functions Preganglionic neurons in the CNS send axons to synapse on postganglionic neurons in autonomic ganglia outside the CNS

Components of the ANS Sympathetic division (thoracolumbar, “fight or flight”) Thoracic and lumbar segments outflow of the spinal cord Parasympathetic division (craniosacral, “rest and repose”) Preganglionic fibers leaving the brain and sacral segments of the spinal cord

I. The Sympathetic Division

Sympathetic division anatomy Preganglionic neurons between segments T1 and L2 of the spinal cord Ganglionic neurons in ganglia near vertebral column Specialized neurons in adrenal glands

The Organization of the Sympathetic Division of the ANS

Sympathetic chain ganglia (paravertebral ganglia) Sympathetic ganglia Sympathetic chain ganglia (paravertebral ganglia) Collateral ganglia (prevertebral ganglia)

Sympathetic Pathways

Sympathetic Pathways

Sympathetic Pathways

Organization and anatomy of the sympathetic division Segments T1-L2, ventral roots give rise to myelinated white ramus Leads to sympathetic chain ganglia

The Distribution of Sympathetic Innervation

Postganglionic fibers Rejoin spinal nerves and reach their destination by way of the dorsal and ventral rami Those targeting structures in the thoracic cavity form sympathetic nerves Go directly to their destination

Abdominopelvic viscera Sympathetic innervation via preganglionic fibers that synapse within collateral ganglia Splanchic nerves

Abdominopelvic viscera Celiac ganglion Innervates stomach, liver, gall bladder, pancreas, spleen Superior mesenteric ganglion Innervates small intestine and initial portion of large intestine Inferior mesenteric ganglion Innervates kidney, urinary bladder, sex organs, and final portion of large intestine

Sympathetic activation In crises, the entire sympathetic division responds Sympathetic activation Affects include increased alertness, energy and euphoria, increased cardiovascular and respiratory activities, elevation in muscle tone, mobilization of energy resources

Neurotransmitters and sympathetic function Stimulation of sympathetic division has two distinct results Release of ACh or NE at specific locations Secretion of E and NE into general circulation Most postganglionic fibers are adrenergic, a few are cholinergic or nitroxidergic Two types of receptors are alpha receptors and beta receptors Sympathetic ganglionic neurons end in telodendria studded with varicosities filled with neurotransmitter

Sympathetic Variosities

II.The Parasympathetic Division

Parasympathetic division of A.N.S Preganglionic neurons in the brainstem and sacral segments of spinal cord Ganglionic neurons in peripheral ganglia located within or near target organs

The Organization of the Parasympathetic Division of the ANS

Organization and anatomy of the parasympathetic division Preganglionic fibers leave the brain as cranial nerves III, VI, IX, X Sacral neurons form the pelvic nerves S2,3,4

The Distribution of Parasympathetic Innervation

Parasympathetic activation Effects produced by the parasympathetic division relaxation food processing energy absorption

Neurotransmitters and parasympathetic functions All parasympathetic fibers release ACh Short-lived response as ACH is broken down by AChE and tissue cholinesterase Postsynaptic membranes have two kinds of receptors Muscarinic Nicotinic

Sympathetic and parasympathetic divisions Widespread influence on visceral and somatic structures Parasympathetic Innervates only visceral structures serviced by cranial nerves or lying within the abdominopelvic cavity Dual innervation = organs that receive input from both systems

Anatomy of dual innervation Sympathetic and parasympathetic systems intermingle to form autonomic plexuses Cardiac plexus Pulmonary plexus Esophageal plexus Celiac plexus Inferior mesenteric plexus Hypogastric plexus

The Autonomic Plexuses

Comparison of the two divisions Important physiological and functional differences exist

The Anatomical Differences between the Sympathetic and Parasympathetic Divisions

Integration and Control of Autonomic Functions

Visceral Reflexes

Higher levels of autonomic control Activity in the ANS is controlled by centers in the brainstem that deal with visceral functioning

Levels of Autonomic Control

A Comparison of Somatic and Autonomic Function

Memory Storage

Consciousness Deep sleep, the body relaxes and cerebral cortex activity is low REM sleep active dreaming occurs The reticular activating system (RAS) is important to arousal and maintenance of consciousness

The Reticular Activating System