Lecture Human anatomy and physiology - Chapter 14: The autonomic nervous system

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Chapter 14 provides knowledge of the autonomic nervous system. In this chapter, you will learn to: Define autonomic nervous system and explain its relationship to the peripheral nervous system; compare the somatic and autonomic nervous systems relative to effectors, efferent pathways, and neurotransmitters released; compare and contrast the functions of the parasympathetic and sympathetic divisions;...

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Nội dung Text: Lecture Human anatomy and physiology - Chapter 14: The autonomic nervous system

PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College CHAPTER 14 The Autonomic Nervous System Copyright © 2010 Pearson Education, Inc.
Autonomic Nervous System (ANS) • The ANS consists of motor neurons that: • Innervate smooth and cardiac muscle and glands • Make adjustments to ensure optimal support for body activities • Operate via subconscious control Copyright © 2010 Pearson Education, Inc.
Autonomic Nervous System (ANS) • Other names • Involuntary nervous system • General visceral motor system Copyright © 2010 Pearson Education, Inc.
Central nervous system (CNS) Peripheral nervous system (PNS) Sensory (afferent) Motor (efferent) division division Somatic nervous Autonomic nervous system system (ANS) Sympathetic Parasympathetic division division Copyright © 2010 Pearson Education, Inc. Figure 14.1
Somatic and Autonomic Nervous Systems • The two systems differ in • Effectors • Efferent pathways (and their neurotransmitters) • Target organ responses to neurotransmitters Copyright © 2010 Pearson Education, Inc.
Effectors • Somatic nervous system • Skeletal muscles • ANS • Cardiac muscle • Smooth muscle • Glands Copyright © 2010 Pearson Education, Inc.
Efferent Pathways • Somatic nervous system • A, thick, heavily myelinated somatic motor fiber makes up each pathway from the CNS to the muscle • ANS pathway is a two-neuron chain 1. Preganglionic neuron (in CNS) has a thin, lightly myelinated preganglionic axon 2. Ganglionic neuron in autonomic ganglion has an unmyelinated postganglionic axon that extends to the effector organ Copyright © 2010 Pearson Education, Inc.
Neurotransmitter Effects • Somatic nervous system • All somatic motor neurons release acetylcholine (ACh) • Effects are always stimulatory • ANS • Preganglionic fibers release ACh • Postganglionic fibers release norepinephrine or ACh at effectors • Effect is either stimulatory or inhibitory, depending on type of receptors Copyright © 2010 Pearson Education, Inc.
Neuro- Cell bodies in central transmitter Effector nervous system Peripheral nervous system at effector organs Effect Single neuron from CNS to effector organs NERVOUS SOMATIC SYSTEM ACh + Heavily myelinated axon Stimulatory Skeletal muscle Two-neuron chain from CNS to effector organs ACh NE AUTONOMIC NERVOUS SYSTEM SYMPATHETIC Unmyelinated postganglionic axon Lightly myelinated Ganglion preganglionic axons Epinephrine and norepinephrine + ACh Stimulatory or inhibitory, depending Adrenal medulla Blood vessel on neuro- transmitter PARASYMPATHETIC and ACh ACh receptors Smooth muscle (e.g., in gut), on effector Lightly myelinated glands, cardiac organs Unmyelinated preganglionic axon postganglionic muscle Ganglion axon Acetylcholine (ACh) Norepinephrine (NE) Copyright © 2010 Pearson Education, Inc. Figure 14.2
Divisions of the ANS 1.Sympathetic division 2.Parasympathetic division • Dual innervation • Almost all visceral organs are served by both divisions, but they cause opposite effects Copyright © 2010 Pearson Education, Inc.
Role of the Parasympathetic Division • Promotes maintenance activities and conserves body energy • Its activity is illustrated in a person who relaxes, reading, after a meal • Blood pressure, heart rate, and respiratory rates are low • Gastrointestinal tract activity is high • Pupils are constricted and lenses are accommodated for close vision Copyright © 2010 Pearson Education, Inc.
Role of the Sympathetic Division • Mobilizes the body during activity; is the “fight- or-flight” system • Promotes adjustments during exercise, or when threatened • Blood flow is shunted to skeletal muscles and heart • Bronchioles dilate • Liver releases glucose Copyright © 2010 Pearson Education, Inc.
ANS Anatomy Origin of Length of Location Division Fibers Fibers of Ganglia Sympathetic Thoracolumbar Short Close to region of the preganglionic spinal cord spinal cord and long postganglionic Parasympathetic Brain and Long In visceral sacral spinal preganglionic effector cord and short organs (craniosacral) postganglionic Copyright © 2010 Pearson Education, Inc.
Parasympathetic Sympathetic Eye Eye Brain stem Salivary Skin* glands Cranial Salivary Sympathetic glands ganglia Heart Cervical Lungs Lungs T1 Heart Stomach Thoracic Stomach Pancreas Liver Pancreas and gall- L1 bladder Liver and Adrenal gall- Lumbar gland bladder Bladder Bladder Genitals Genitals Sacral Copyright © 2010 Pearson Education, Inc. Figure 14.3
Parasympathetic (Craniosacral) Division Outflow Cranial Nerve Ganglia Effector Organ(s) Cranial (Terminal Ganglia) Outflow Oculomotor (III) Ciliary Eye Facial (VII) Pterygopalatine Salivary, nasal, and Submandibular lacrimal glands Glossopharyngeal Otic Parotid salivary glands (IX) Vagus (X) Within the walls of Heart, lungs, and most target organs visceral organs Within the walls of Large intestine, Sacral S2-S4 target organs urinary bladder, Outflow ureters, and reproductive organs Copyright © 2010 Pearson Education, Inc.
CN III Ciliary Eye ganglion Lacrimal gland CN VII Pterygopalatine CN IX ganglion Nasal CN X mucosa Submandibular ganglion Submandibular and sublingual Otic ganglion glands Parotid gland Heart Cardiac and pulmonary plexuses Lung Liver and Celiac gallbladder plexus Stomach Pancreas S2 Large S4 intestine Pelvic Small splanchnic intestine nerves Inferior Rectum hypogastric plexus Urinary Preganglionic Genitalia bladder Postganglionic (penis, and ureters Cranial nerve clitoris, and vagina) Copyright © 2010 Pearson Education, Inc. Figure 14.4
Sympathetic (Thoracolumbar) Division • Preganglionic neurons are in spinal cord segments T1 – L2 • Sympathetic neurons produce the lateral horns of the spinal cord • Preganglionic fibers pass through the white rami communicantes and enter sympathetic trunk (paravertebral) ganglia Copyright © 2010 Pearson Education, Inc.
Eye Lacrimal gland Pons Nasal mucosa Sympathetic trunk (chain) ganglia Blood vessels; Superior skin (arrector pili cervical muscles and sweat glands) ganglion Salivary glands Middle cervical ganglion Heart Inferior cervical Cardiac and ganglion pulmonary Lung T1 plexuses Greater splanchnic nerve Lesser splanchnic nerve Liver and Celiac ganglion gallbladder L2 Stomach White rami Superior communicantes mesenteric Spleen ganglion Adrenal medulla Kidney Sacral splanchnic nerves Lumbar Inferior Small splanchnic mesenteric intestine nerves ganglion Large intestine Rectum Preganglionic Postganglionic Genitalia (uterus, vagina, and penis) and urinary bladder Copyright © 2010 Pearson Education, Inc. Figure 14.6
Sympathetic Trunks and Pathways • There are 23 paravertebral ganglia in the sympathetic trunk (chain) • 3 cervical • 11 thoracic • 4 lumbar • 4 sacral • 1 coccygeal Copyright © 2010 Pearson Education, Inc.
Spinal cord Dorsal root Ventral root Rib Sympathetic trunk ganglion Sympathetic trunk Ventral ramus of spinal nerve Gray ramus communicans White ramus communicans Thoracic splanchnic nerves (a) Location of the sympathetic trunk Copyright © 2010 Pearson Education, Inc. Figure 14.5a