Enteric Nervous System Innervations are from sympathetic and parasympathetic divisions of ANS, which control on intramural plexus (myenteric/auerbach plexus and meissner’s plexus). Intramural plexus made up of 108 neurons which is almost equal to number of neurons in spinal cord. Sympathetic division made of thoracolumbar outflow has got preganglionic cholinergic nerve fibres. They end upon coeliac […]

Reflex activities of Autonomic Nervous System Autonomic reflexes These reflexes arc, similar to somatic reflex arc have Sensory part Motor part. Visceral sensory fibers enter the dorsal horn of spinal cord, branching into spinal sensory column. They employ interneurons. Interneurons transmit impulses to the preganglionic neurons in the spinal cord or to the brain stem.

Functions of sympathetic and parasympathetic divisions Effector organ Sympathetic Receptor Parasympathetic Heart S A node Increased in heart rate        b1   Decrease in heart rate  Atria Increase contractility and conduction velocity b1 ¯ contractility &­ conduction velocity AV node and Conduction system ­ conduction velocity b1 ¯ conduction velocity Ventricles contractility & conduction velocity b2 — ArteriolesCoronary, skeletal, Pulmonary, renal,

Physiology of Parasympathetic nervous system The parasympathetic nervous system is composed mainly of the cranial and sacral spinal nerves. The preganglionic neurons, arising from either the brain or sacral spinal cord, synapse with just a few postganglionic neurons which are located in or near the effector organ (muscle or gland). The parasympathetic nervous system is responsible for the body’s rest and

Physiology of Sympathetic nervous system Cell bodies of preganlionic sympathetic fibers are located on the intermedia lateral column of thoracic & upper lumbar spinal cord Fibers from these nucleus emerge out through respective spinal nerves from ventral root of the spinal cord. Short fibres of pre ganglionic system synapse with autonomic ganglia. Sympathetic trunk Sympathetic

Neuro transmitters of Autonomic Nervous System Acetyl choline (Ach) This is the neuro transmitter produced by preganglionic fibers of both sympathetic & parasympathetic systems. Post ganglionic fiber of parasympathetic system produce Ach at their neuro effector site in visceral organ Adrenaline/Nor-adrenaline Post ganglionic fibers of sympathetic system produce noradrenaline or adrenaline at their neuro effector site on the effector organs. Exception–

Segment of Autonomic Nervous System The ANS is divided into small segments after its origin from CNS. Three segments are Cranial segment, Thoraco lumbar segment and Sacral segment. Cranial segment From brain stem with nerve fibers of oculomotor, facial, Glossopharyngeal & Vagus Thoraco lumbar segment From spinal cord with ventral root of spinal nerves from T1 or L5or6 segments. Sacral

Nerve fibers of ANS Ganglia possess two types of nerve fibers- Pre ganglionic nerve fiber and Post ganglionic nerve fiber. Pre ganglionic nerve fiber Nerve fiber from CNS to cells of ganglia for synapse. Pre ganglionic nerve fiber are small, myelinated with conduction velocity of 3-15 m/sec, representing class B fiber. Post ganglionic nerve fiber

Classification of ganglia Vertebral ganglia Vertebral ganglia located along vertebral column and are associated with sympathetic trunk. Collateral ganglia Collateral ganglia located in between CNS and viscera, associated with visceral blood vessels. eg. celiac ,pelvic and cranial & caudal mesentric Terminal ganglia Terminal ganglia located in the wall of the visceral organ eg. Cardiac, pulmonary & enteric ganglia.

Autonomic Nervous System or ANS Autonomic Nervous System or ANS described as visceral efferent system by Langley in 1898. All efferent axons leaving the CNS other than those of skeletal muscle belong to ANS. ANS supplies efferent information to smooth muscle, glands & cardiac muscle. ANS modifies motor activities that have been initiated with in