The Autonomic Nervous System: Regulating Visceral Functions

1. 15 PART 1 The Autonomic Nervous System Pages 468-480

2. The ANS and Visceral Sensory Neurons • The ANS—a system of motor neurons • Regulates visceral functions • Heart rate • Blood pressure • Digestion • Urination • The ANS is the • General visceral motor division of the PNS

3. The Autonomic Nervous System and Visceral Sensory Neurons Figure 15.1

4. Comparison of Autonomic and Somatic Motor Systems • Somatic motor system • One motor neuron extends from the CNS to skeletal muscle • Axons are well myelinated, conduct impulses rapidly • 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

5. Figure 15.2 Comparing Somatic Motor and Autonomic Innervation

6. Cell bodies in central nervous system Neurotransmitter at effector Effector organs Peripheral nervous system Effect Single neuron from CNS to effector organs SOMATIC NERVOUS SYSTEM ACh Stimulatory Heavily myelinated axon Skeletal muscle Two-neuron chain from CNS to effector organs NE ACh Unmyelinated postganglionic axon SYMPATHETIC Lightly myelinated preganglionic axons Ganglion Epinephrine and norepinephrine ACh Stimulatory or inhibitory, depending on neuro- transmitter and receptors on effector organs AUTONOMIC NERVOUS SYSTEM Adrenal medulla Blood vessel ACh ACh Smooth muscle (e.g., in gut), glands, cardiac muscle PARASYMPATHETIC Unmyelinated postganglionic axon Lightly myelinated preganglionic axon Ganglion Autonomic and Somatic Motor Systems

7. Divisions of the Autonomic Nervous System • Sympathetic and parasympathetic divisions • Chains of two motor neurons • Innervate mostly the same structures • Cause opposite effects • Sympathetic division mobilizes the body during extreme situations • Parasympathetic division controls routine maintenance functions

9. Divisions of the Autonomic Nervous System • Sympathetic—“fight, flight, or fright” • Activated during EXTREME situations • Sympathetic responses help us respond to dangerous situations • Increase heart rate and breathing rate • Increases blood and oxygen to skeletal muscles • Dilates pupils and airways • Motility of the digestive tract and urinary tracts are inhibited

10. Divisions of the Autonomic Nervous System • Parasympathetic division • Active when the body is at rest • Concerned with conserving energy • Directs “housekeeping” activities • Heart rate and breathing are at low-normal levels • Gastrointestinal tract digests food • Pupils are constricted

12. Parasympathetic Sympathetic Eye Eye Brain stem Salivary glands Skin* Cranial Salivary glands Sympathetic ganglia Heart Cervical Lungs Lungs T1 Heart Stomach Thoracic Pancreas Stomach Liver and gall- bladder Pancreas L1 Adrenal gland Liver and gall- bladder Lumbar Bladder Bladder Genitals Genitals Sacral 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

13. Anatomical Differences in Sympatheticand 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

14. Biochemical Differences in Sympatheticand Parasympathetic Divisions • Neurotransmitter released by postganglionic axons • Sympathetic • Most release norepinephrine (adrenergic) • Parasympathetic • Release acetylcholine (cholinergic)

15. Parasympathetic and Sympathetic Divisions Table 15.1

16. 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

17. Cranial Outflow (Parasympathetic) • Preganglionic fibers run via • Oculomotor nerve (III) • Facial nerve (VII) • Glossopharyngeal nerve (IX) • Vagus nerve (X) • Cell bodies of preganglionic neurons located in cranial nerve nuclei in the brain stem

18. Eye Ciliary ganglion CN III Lacrimal gland CN VII Pterygopalatine ganglion Nasal mucosa CN IX CN X Submandibular ganglion Submandibular and sublingual glands Otic ganglion Parotid gland Heart Cardiac and pulmonary plexuses Lung Liver and gallbladder Celiac plexus Stomach Pancreas S2 Large intestine S4 Small intestine Pelvic splanchnic nerves Inferior hypogastric plexus Rectum Urinary bladder and ureters Genitalia (penis, clitoris, and vagina) Preganglionic Postganglionic CN Cranial nerve The Parasympathetic Division Figure 15.4

19. Outflow via the Oculomotor Nerve (III) • Parasympathetic fibers innervate smooth muscles in the eye • Cause pupil constriction • Preganglionic cell bodies • Located in the oculomotor nucleus in the midbrain • Post ganglionic cell bodies • Lie in the ciliary ganglion

20. Outflow via the Facial Nerve (VII) • Parasympathetic fibers stimulate secretion of glands in the head • Lacrimal nucleus • Located in the pons • Synapse in the pterygopalatine ganglion • Superior salivatory nucleus • Located in the pons • Synapse in the submandibular ganglion

21. Eye Ciliary ganglion CN III Lacrimal gland CN VII Pterygopalatine ganglion Nasal mucosa CN IX CN X Submandibular ganglion Submandibular and sublingual glands Otic ganglion Parotid gland Heart Cardiac and pulmonary plexuses Lung Liver and gallbladder Celiac plexus Stomach Pancreas S2 Large intestine S4 Small intestine Pelvic splanchnic nerves Inferior hypogastric plexus Rectum Urinary bladder and ureters Genitalia (penis, clitoris, and vagina) Preganglionic Postganglionic CN Cranial nerve The Parasympathetic Division Figure 15.4

22. Outflow via the Glossopharyngeal Nerve (IX) • Parasympathetic fibers • Stimulate secretion of parotid gland • Inferior salivatory nucleus—located in the medulla • Synapse in the otic ganglion

23. Outflow via the Vagus Nerve (X) • Fibers innervate visceral organs of the thorax and most of the abdomen • Stimulates: • Digestion, reduction in heart rate, and reduction in blood pressure • Preganglionic cell bodies • Located in dorsal motor nucleus in the medulla • Postganglionic neurons • Confined within the walls of organs being innervated • Cell bodies form intramural ganglia

24. Eye Ciliary ganglion CN III Lacrimal gland CN VII Pterygopalatine ganglion Nasal mucosa CN IX CN X Submandibular ganglion Submandibular and sublingual glands Otic ganglion Parotid gland Heart Cardiac and pulmonary plexuses Lung Liver and gallbladder Celiac plexus Stomach Pancreas S2 Large intestine S4 Small intestine Pelvic splanchnic nerves Inferior hypogastric plexus Rectum Urinary bladder and ureters Genitalia (penis, clitoris, and vagina) Preganglionic Postganglionic CN Cranial nerve The Parasympathetic Division Figure 15.4

25. Path of the Vagus Nerve • Sends branches through • Autonomic nerve plexuses • Cardiac plexus • Pulmonary plexus • Esophageal plexus • Celiac plexus • Superior mesenteric plexus

26. Superior cervical ganglion Left vagus nerve Cardiac branches of the vagus Trachea Middle cervical ganglion Thoracic spinal nerves (ventral rami) Stellate ganglion Cardiac plexus Sympathetic cardiac nerves Pulmonary plexus on the bronchus Aorta Aortic arch Vagus nerve Sympathetic trunk ganglia Esophageal plexus Diaphragm Stomach with vagus nerve Esophagus Celiac ganglion and plexus Thoracic splanchnic nerves Superior mesenteric ganglion and plexus Adrenal (suprarenal) gland Aortic plexus Inferior mesenteric ganglion and plexus Kidney Superior hypogastric plexus Lumbar and sacral splanchnic nerves Inferior hypogastric (pelvic) plexus Pelvic sympathetic trunk Autonomic nerves, plexuses and ganglia Figure 15.5

27. Sacral Outflow • Emerges from S2–S4 • Innervates organs of the pelvis and lower abdomen • Preganglionic cell bodies • Located in visceral motor region of spinal gray matter • Axons run in ventral roots to ventral rami

28. Dorsal root (sensory) Dorsal horn (interneurons) Dorsal root ganglion SS Somatic sensory neuron VS VM Visceral sensory neuron SM Visceral motor neuron Ventral horn (motor neurons) Somatic motor neuron Spinal nerve Ventral root (motor) Interneurons receiving input from somatic sensory neurons Interneurons receiving input from visceral sensory neurons Visceral motor (autonomic) neurons Somatic motor neurons Gray Matter of the Spinal Cord and Spinal Roots Figure 13.27

29. Dorsal median sulcus Gray commissure Dorsal funiculus Dorsal horn Gray matter Ventral funiculus White matter Ventral horn Lateral horn Lateral funiculus Dorsal root ganglion Spinal nerve Central canal Dorsal root (fans out into dorsal rootlets) Ventral median fissure Ventral root (derived from several ventral rootlets) Pia mater Arachnoid mater Spinal dura mater (b) The spinal cord and its meningeal coverings Anatomy of the Spinal Cord Figure 13.26

30. 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; sympathetic trunk ganglia & collateral ganglia

31. Sympathetic Trunk Ganglia • Located on both sides of the vertebral column • Linked by short nerves into sympathetic trunks • Sympathetic trunk ganglia are also called • Chain ganglia • Joined to ventral rami by white and gray rami communicantes

32. Spinal cord Lateral horn (visceral motor zone) Dorsal root Dorsal root Dorsal root ganglion Ventral root Dorsal ramus of spinal nerve Rib Ventral ramus of spinal nerve Sympathetic trunk ganglion Gray ramus communicans Ventral root Sympathetic trunk White ramus communicans Sympathetic trunk ganglion Ventral ramus of spinal nerve Sympathetic trunk Skin (arrector pili muscles and sweat glands) 1 Synapse at the same level Gray ramus communicans To effector White ramus communicans Thoracic splanchnic nerves Blood vessels (a) Location of the sympathetic trunk Splanchnic nerve Collateral ganglion (such as the celiac) Skin (arrector pili muscles and sweat glands) Target organ in abdomen (e.g., intestine) To effector 3 Synapse in a distant collateral ganglion anterior to the vertebral column Synapse at a higher or lower level 2 Blood vessels (b) Three pathways of sympathetic innervation Sympathetic Trunk Ganglia Figures 15.6 & 15.7

33. Sympathetic Pathways • Preganglionic axons follow one of three pathways • Synapes with a postganglionic neuron at the same level and exit on a spinal nerve at that level • Axon ascends or descends in the sympathetic trunk to synapse in another ganglion • Axon passes through the sympathetic trunk and exits on a splanchnic nerve

34. Eye Lacrimal gland Nasal mucosa Pons Sympathetic trunk (chain) ganglia Blood vessels; skin (arrector pili muscles and sweat glands) Superior cervical ganglion Middle cervical ganglion Salivary glands Heart Inferior cervical ganglion Cardiac and pulmonary plexuses Lung T1 Greater splanchnic nerve Lesser splanchnic nerve Liver and gallbladder Celiac ganglion L2 Stomach Superior mesenteric ganglion White rami communicantes Spleen Adrenal medulla Kidney Sacral splanchnic nerves Lumbar splanchnic nerves Small intestine Inferior mesenteric ganglion Large intestine Rectum Preganglionic Postganglionic Genitalia (uterus, vagina, and penis) and urinary bladder Sympathetic Pathways to Organs Figure 15.8

35. 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

36. Sympathetic trunk Spinal cord: T8–L1 Ventral root Thoracic splanchnic nerves Kidney Adrenal gland Adrenal medulla Epinephrine and norepinephrine Capillary Adrenal medulla cells The Adrenal Medulla Figure 15.9

37. Table 15.2 (1 of 3)

38. Table 15.2 (2 of 3)

39. Table 15.2 (3 of 3)