Anatomy and Physiology Autonomic Nervous System Marieb’s Human Anatomy and Physiology Marieb w Hoehn Chapter 14 Autonomic Nervous System Lecture 21

Autonomic (Visceral) Nervous System CNS PNS

Autonomic Nervous System functions without conscious effort controls visceral (squishy!) activities regulates smooth muscle, cardiac muscle, and glands Two Main Divisions sympathetic – prepares body for fight or flight situations parasympathetic – prepares body for rest and digest activities Third Division – Enteric Nervous System (ENS) Enteric – related to the intestines

Somatic vs. Autonomic Nervous Systems Dual Figure from: Marieb, Human Anatomy & Physiology, Pearson, 2013

Autonomic Nerve Fibers Figure from: Hole’s Human A&P, 12th edition, 2010 *ANS = a motor division of the PNS

Overview of Sympathetic NS From: http://home.comcast.net/~wnor/thoraxlesson5.htm From: http://www.nature.com/gimo/contents/pt1/fig_tab/gimo6_F4.html

Sympathetic Division of ANS * Paravertebral ganglion Effectors in head and thoracic cavity Effectors in muscles and body wall * * (T5 – T12) 1- Preganglionic fibers that synapse within the ganglion 2 – Preganglionic fibers that extend up or down within the sympathetic trunk 3 – Preganglionic fibers that synapse in collateral ganglia NOTE: Arrangement of nerves creates DIVERGENCE Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

Sympathetic Division of the ANS SYMPATHETIC (Thoracolumbar outflow) Fight or Flight “E” situations Emergency Embarrassment Excitement Exercise Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Sympathetic Division - Divergence NOTE: Arrangement of nerves creates DIVERGENCE There are between 15 and 20 postganglionic fibers for every preganglionic neuron in the sympathetic nervous system. Sympathy spreads…

Parasympathetic (Craniosacral outflow) “REST AND DIGEST” Salivation Lacrimation Urination Digestion Defecation 3 decreases - Heart rate - Airway diameter - Pupil size (constrict) Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

Autonomic Plexuses Sympathetic collateral (prevertebral) ganglia (Solar plexus) Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 Autonomic plexuses contain sympathetic and parasympathetic postganglionic fibers

Autonomic Neurotransmitters = always excitatory in ganglia You should know which neurotransmitters are released, and the locations where they are released

Sympathetic Myoneural Junctions Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004 NE is either: reabsorbed and reused or broken down by monoamine oxidase (MAO) in varicosities or broken down by catechol-O-methyltransferase (COMT) in surrounding tissues

Actions of Autonomic Neurotransmitters depend on receptor Cholinergic receptors bind acetylcholine nicotinic excitatory muscarinic excitatory or inhibitory Adrenergic receptors bind norepinephrine alpha (Types 1 and 2) different responses on various effectors beta (Types 1 and 2)

Actions of Cholinergic Receptors Nicotinic receptors  always excitatory Muscarinic  Excitatory or inhibitory Remember: the RECEPTOR determines the effect of a neurotransmitter Always excitatory (Sweat glands, blood vessels to skeletal muscles, brain)

Control of Autonomic Activity Sympathetic and Parasympathetic Sympathetic Parasympathetic Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Review of Autonomic Nervous System Branch of ANS PARASYMPATHETIC SYMPATHETIC General Function * “rest and digest” * (SLUDD); Salivation, lacrimation, urination, digestion, defecation * 3 decreses; ↓ heart rate, ↓ pupil size, ↓ airway diameter * “fight or flight” * E situations: Emergency, exercise, embarassment, excitement Origin of Preganglionic fiber cranial region of brain or sacral region of spinal cord (craniosacral outflow) thoracic or lumbar region of spinal cord (thoracolumbar outflow) Divergence for widespread activation of body Location of Ganglia within or near effector organ alongside or in front of spinal cord (paravertebral ganglia; collateral ganglia) NTx secreted by postganglionic fiber acetylcholine Norepinephrine (some acetylcholine; sweat glands, smooth muscle on blood vessels, brain) Good summary chart to know

Review The autonomic nervous system (ANS) Controls visceral activities involuntarily Sympathetic (thoracolumbar) = fight or flight Parasympathetic (craniosacral) = rest and digest Efferent fibers synapse in ganglia outside CNS NTx of the ANS Acetylcholine (cholinergic) – pre- and postganglionic parasympathetic and preganglionic sympathetic Adrenergic (norepinephrine) – postganglionic sympathetic ONLY