The Autonomic Nervous System and Visceral Sensory Neurons PART 1 The Autonomic Nervous System and Visceral Sensory Neurons

The ANS and Visceral Sensory Neurons The ANS – a system of motor neurons Remember, we’re on the motor side, visceral! Innervates Smooth muscle GI Tract, Respiratory Tract Cardiac muscle - Heart Glands – Endocrine REGULATES: heart rate, blood pressure, digestion and urination Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System and Visceral Sensory Neurons Figure 15.1 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Comparison of Autonomic and Somatic Motor Systems One motor neuron extends from the CNS to skeletal muscle Axons are well myelinated, conduct impulses rapidly Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Comparison of Autonomic and Somatic Motor Systems Autonomic nervous system Chain of two motor neurons Preganglionic neuron PostGanglionic neuron Conduction is slower than somatic nervous system due to Thinly myelinated or unmyelinated axons Motor neuron synapses in a ganglion Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Autonomic and Somatic Motor Systems Figure 15.2 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Divisions of the Autonomic Nervous System Sympathetic and parasympathetic divisions Chains of two motor neurons Innervate mostly the same structures Cause opposite effects Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Divisions of the Autonomic Nervous System Sympathetic – “fight, flight, or fright” Activated during EXTREME situations Exercise Excitement Emergencies Parasympathetic – “rest and digest” Concerned with conserving energy Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Issue from different regions of the CNS Sympathetic – also called the thoracolumbar division Parasympathetic – also called the craniosacral division Figure 15.3 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Length of postganglionic fibers Sympathetic – long postganglionic fibers Parasympathetic – short postganglionic fibers Branching of axons Sympathetic axons – highly branched Influences many organs Parasympathetic axons – few branches Localized effect Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Neurotransmitter released by postganglionic axons Sympathetic – most release norepinephrine (adrenergic) Parasympathetic – release acetylcholine (cholinergic) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Figure 15.4a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anatomical Differences in Sympathetic and Parasympathetic Divisions Figure 15.4b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Parasympathetic and Sympathetic Divisions Table 15.1 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Parasympathetic Division Cranial outflow Comes from the brain Innervates Organs of the head, neck, thorax, and abdomen Sacral outflow Innervation supplies Remaining abdominal and pelvic organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Parasympathetic Division Figure 15.5 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Path of the Vagus Nerve Figure 15.6 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Sympathetic Division Basic organization Issues from T1–L2 Preganglionic fibers form the lateral gray horn Supplies visceral organs and structures of superficial body regions Contains more ganglia than the parasympathetic division Located on both sides of the vertebral column Linked by short nerves into sympathetic trunks Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Trunk Ganglia Figure 15.8 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Division of the ANS Figure 15.7 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Pathways to the Body Periphery Innervate Sweat glands Arrector pili muscles Peripheral blood vessels Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sympathetic Pathways to the Body Periphery Figure 15.9 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Role of the Adrenal Medulla in the Sympathetic Division Major organ of the sympathetic nervous system Constitutes largest sympathetic ganglia Secretes great quantities of norepinephrine and adrenaline Stimulated to secrete by preganglionic sympathetic fibers Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Adrenal Medulla Figure 15.14 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Table 15.2 (1 of 3) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Table 15.2 (2 of 3) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Table 15.2 (3 of 3) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Visceral Sensory Neurons General visceral sensory neurons monitor Stretch, temperature, chemical changes, and irritation Cell bodies are located in the dorsal root ganglion Visceral pain – perceived to be somatic in origin and is called  referred pain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

A Map of Referred Pain Figure 15.15 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings