Autonomic Nervous System basic anatomy of ANS ANS vs PNS divisions of ANS sympathetic division anatomy & function ANS plexuses sympathetic response adrenal gland parasympathetic division visceral reflexes stress & the ANS referred pain anatomy

CNS PNS Sensory Motor Visceral Somatic Parasympathetic Sympathetic Somatic & visceral Motor Visceral Somatic Parasympathetic Sympathetic

Autonomic Nervous System Visceral sensory & motor system Innervates viscera, smooth muscle and glands Autonomic = self governed Adjusts visceral functions to the body’s needs Responsible for visceral reflexes CN IX High BP CN X What is “visceral sensory” info?? examples Decrease Heart rate

Somatic efferent innervation Visceral efferent innervation ACh = Acetylcholine NE = Norepinephrine Somatic efferent innervation ACh Visceral efferent innervation ACh or NE ACh Note that brain connection is missing here! Autonomic ganglion

Basic anatomy of ANS Preganglionic neuron Postganglionic neuron cell body in brain or spinal cord (lateral horn) axon is myelinated Synapses in ganglion Postganglionic neuron cell body in autonomic ganglion axon is unmyelinated synapses on visceral effector

Sympathetic Parasympathetic Speeds up Fight or flight slows down rest & digest

Sympathetic division (thoracolumbar) preganglionic neuron cell body in T1-L2 of spinal cord Ganglia near spine connected by a chain (sympathetic chain) Short preganglionic neuron Long postganglionic neuron Parasympathetic division (craniosacral) preganglionic neuron cell body in S2-S4 of spinal cord & brainstem CN’s III, VII, IX & X Ganglia in organ wall Ganglia are not connected Long preganglionic neuron Short postganglionic neuron

Anatomy of sympathetic chain Posterior (dorsal) Dorsal ramus Communicating rami Ventral ramus Sympathetic ganglion Anterior (ventral)

Sympathetic chain in thorax

Sympathetic innervation of the heart brain

Sympathetic pathways BILATERAL (right & left) sympathetic pathways all this innervation is BILATERAL (right & left) sympathetic pathways innervate sweat gland, arrector pili & smooth muscle of blood vessels peripherally organ responses? carry noxious sensory information (except in pelvis)

Adrenal gland Adrenal cortex Adrenal medulla Cortex = steroid hormones (endocrine system) Medulla = modified sympathetic ganglion secretes epinephrine (adrenaline) & norepinephrine innervated by preganglionic sympathetic neurons products get secreted into bloodstream

Remember a stressful event What was that event List 5 changes that occurred in your body that you noticed during the event How long did it take for the stress response to go away?

Parasympathetic pathways Cranial nerves: III, VII, IX & X Sacral nerves S2-S4 NT = acetylcholine Also bilateral innervation Carries most sensory info except noxious stimuli

Plexuses of ANS sympathetic + parasympathetic Cardiac plexus Pulmonary plexus Celiac (solar) plexus Superior mesenteric Inferior mesenteric Hypogastric

Visceral reflex CN IX CN IX Low BP High BP sympathetic CN X Vagus Increase HR And constrict BV Decrease HR And dilate BV Beta adrenergic blockers Block sympathetic response

parasympathetic response bronchospasm increased gland activity vagus vagus Asthma parasympathetic response bronchospasm increased gland activity treat with B2 adrenergic agonists (stimulate sympathetic response)

T1-T4 receive visceral afferents from heart T1 dermatome Sensory from skin = green Sensory from heart = red

Referred Pain Organ & skin pain fibers travel to the spinal cord together Organ pain misinterpreted as skin pain (referred pain) Heart & skin in left arm = spinal nerves T1-T5 Heart attack (pain) is felt in skin (pain) along left arm & chest

What is STRESS? Short term “amp” to long term amp Year after year…… Problems! - hypertension - ulcers - constipation - bladder infections - Raynaud’s - sexual dysfunction