PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 15 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Autonomic Nervous System and Visceral Sensory Neurons PART 2

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sacral Outflow  Emerges from S 2 –S 4  Innervates organs of the pelvis and lower abdomen  Preganglionic cell bodies  Located in visceral motor region of spinal gray matter

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sacral Outflow  Axons run in ventral roots to ventral rami  Form splanchnic nerves  Run through the inferior hypogastric plexus

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Sympathetic Division  Basic organization  Issues from T 1 –L 2  Preganglionic fibers form the lateral gray horn  Supplies visceral organs and structures of superficial body regions  Contains more ganglia than the parasympathetic division

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Trunk Ganglia  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  Joined to ventral rami by white and gray rami communicantes  Fusion of ganglia  fewer ganglia than spinal nerves

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

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Prevertebral Ganglia  Unpaired, not segmentally arranged  Occur only in abdomen and pelvis  Lie anterior to the vertebral column  Main ganglia  Celiac, superior mesenteric, inferior mesenteric, and inferior hypogastric ganglia

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 Sympathetic Pathways to the Head  Preganglionic fibers originate in spinal cord at T 1 –T 4  Fibers ascend in the sympathetic trunk  Synapse in superior cervical ganglion

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Head  Postganglionic fibers associate with large arteries  Carried by these structures to  Glands  Smooth muscle  Vessels throughout the head

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Head Figure 15.10

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Thoracic Organs  Preganglionic fibers originate at spinal levels T 1 – T 6  Some fibers synapse in nearest sympathetic trunk ganglion  Postganglionic fibers run directly to the organ supplied

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Thoracic Organs  Sympathetic fibers to heart have a less direct route  Functions  Increase heart rate  Dilate bronchioles  Dilate blood vessels to the heart wall  Inhibit muscles and glands in the esophagus and digestive system

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Thoracic Organs Figure 15.11

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to Abdominal Organs  Preganglionic fibers originate in spinal cord (T 5 – L 2 )  Pass through adjacent sympathetic trunk ganglia  Then travel in thoracic splanchnic nerves  Synapse in prevertebral ganglia on the abdominal aorta  Celiac and superior mesenteric ganglia  Inhibit activity of muscles and glands in visceral organs

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Abdominal Organs Figure 15.12

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Pelvic Organs  Preganglionic fibers originate in spinal cord (T 10 –L 2 )  Some fibers synapse in sympathetic trunk  Other preganglionic fibers synapse in prevertebral ganglia  Postganglionic fibers proceed from plexuses to pelvic organs

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways to the Pelvic Organs Figure 15.13

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  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 Visceral Reflexes  Visceral sensory and autonomic neurons  Participate in visceral reflex arcs  Defecation reflex  Micturition reflex  Some are simple spinal reflexes  Others do not involve the CNS  Strictly peripheral reflexes

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Visceral Reflex Arc Figure 15.16

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Central Control of the ANS  Control by the brain stem and spinal cord  Reticular formation exerts most direct influence  Medulla oblongata  Periaqueductal gray matter  Control by the hypothalamus and amygdala  Hypothalamus – the main integration center of the ANS  Amygdala – main limbic region for emotions  Control by the cerebral cortex

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Central Control of the ANS Figure 15.17

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Disorders of the Autonomic Nervous System  Raynaud’s disease – characterized by constriction of blood vessels  Provoked by exposure to cold or by emotional stress  Hypertension – high blood pressure  Can result from overactive sympathetic vasoconstriction

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Disorders of the Autonomic Nervous System  Mass reflex reaction  Uncontrolled activation of autonomic and somatic motor neurons  Affects quadriplegics and paraplegics  Achalasia of the cardia  Defect in the autonomic innervation of the esophagus

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The ANS Throughout Life  Preganglionic neurons of the ANS develop from the neural tube  Ganglionic neurons develop from the neural crest  Development of the sympathetic division  Some cells migrate ventrally  Form the sympathetic trunk ganglia  Other cells migrate  Form the prevertebral ganglia

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The ANS Throughout Life Figure 15.18

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The ANS Throughout Life  Efficiency of the ANS declines with advancing age  Constipation due to reduced mobility of gastrointestinal (GI) tract  Dry eyes due to reduced tear formation