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PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community Ninth Edition College Human Anatomy & Physiology CHAPTER © Annie Leibovitz/Contact Press Images 14 © 2013 Pearson Education, Inc. Autonomic Nervous System (ANS) • ANS • motor neurons innervate organs • subconscious control Figure 14.1 Place of the ANS in the structural organization of the nervous system. Central nervous system (CNS) Peripheral nervous system (PNS) Sensory (afferent) division Let’s compare Somatic vs. Autonomic Motor (efferent) division Somatic nervous system Autonomic nervous system (ANS) Sympathetic division Parasympathetic division Figure 14.2 Comparison of motor neurons in the somatic and autonomic nervous systems. Cell bodies in central nervous system Neurotransmitter at effector Peripheral nervous system Effector organs Effect SOMATIC NERVOUS SYSTEM Single neuron from CNS to effector organs ACh + Stimulatory Heavily myelinated axon Skeletal muscle Two-neuron chain from CNS to effector organs NE SYMPATHETIC Lightly myelinated preganglionic axons Nonmyelinated postganglionic axon Ganglion ACh Acetylcholine (ACh) Blood vessel ACh ACh Lightly myelinated preganglionic axon +– Epinephrine and norepinephrine Adrenal medulla PARASYMPATHETIC AUTONOMIC NERVOUS SYSTEM ACh Ganglion Nonmyelinated postganglionic axon Smooth muscle (e.g., in gut), glands, cardiac muscle Norepinephrine (NE) So, how does this dual effect work? Stimulatory or inhibitory, depending on neurotransmitter and receptors on effector organs Neurotransmitters • ACh released by • Cholinergic fibers • preganglionic • parasympathetic postganglionic • NE released by • Adrenergic fibers • Most sympathetic postganglionic Receptors for Neurotransmitters • Two major categories of receptors: • Receptors that bind ACh are called Cholinergic receptors • Receptors that bind NE are called Adrenergic receptors Cholinergic Receptors • Two types 1. Nicotinic 2. Muscarinic • What do they bind? • ACh Nicotinic Receptors • Found on • Sarcolemma of NMJ • All postganglionic neurons • Always stimulatory effect • Ion opening à depolarization • what do they bind? • ACh Muscarinic Receptors • Found on • organ cells • that are stimulated by postganglionic cholinergic fibers • inhibitory or excitatory • Depends on receptor type of target organ • use G-proteins • what do they bind? • ACh Adrenergic Receptors • Two major classes • Alpha (α) • α1 : blood vessel constriction • α2: pupil dilation • Beta (β) • β1: ‘have one heart’ – increase heart rate • β2: ‘have two lungs’ – relax bronchiole smooth m. • NE effects depend on • subclass of receptor #s on target organ © 2013 Pearson Education, Inc. Roles © 2013 Pearson Education, Inc. Role of the Parasympathetic Division • Directs • digestion • diuresis • defecation • So, • Energy Conservation • Maintenance activities © 2013 Pearson Education, Inc. Role of the Sympathetic Division • Stimulated during • • • • exercise excitement emergency embarrassment © 2013 Pearson Education, Inc. Location • ANS divisions located in SC in two patterns: • Top/Bottom • Middle © 2013 Pearson Education, Inc. Parasympathetic Eye TOP Sympathetic Brain stem Salivary glands Skin* Cranial Sympathetic ganglia Heart Salivary glands Cervical Lungs Lungs T1 Heart MIDDLE Stomach Stomach Thoracic Pancreas Liver and gallbladder Pancreas L1 Liver and gallbladder BOTTOM Eye Adrenal gland Lumbar Bladder Genitals © 2013 Pearson Education, Inc. Bladder Sacral Genitals Position of ganglia differs Parasympathetic : close to target organ Sympathetic close to spinal cord So what? Think speed… Sympathetic: fast, ‘all-systems come on board’ So, what structures are enervated? Parasympathetic Sympathetic Eye Ciliary ganglion CN III Lacrimal gland CN VII Pterygopalatine ganglion CN IX CN X Submandibular ganglion Otic ganglion Nasal mucosa Submandibular and sublingual glands Parotid gland Heart Cardiac and pulmonary plexuses Lung Celiac plexus Liver and gallbladder Stomach Pancreas S2 Large intestine S4 Small intestine Pelvic splanchnic nerves Inferior hypogastric plexus Rectum Urinary bladder and ureters Genitalia (penis, clitoris, and vagina) CN S © 2013 Pearson Education, Inc. Preganglionic Postganglionic Cranial nerve Sacral nerve Eye Lacrimal gland Nasal mucosa Pons Sympathetic trunk (chain) ganglia Superior cervical ganglion Salivary glands Middle cervical ganglion Inferior cervical ganglion T1 Blood vessels; skin (arrector pili muscles and sweat glands) Heart Cardiac and pulmonary plexuses Greater splanchnic nerve Lesser splanchnic nerve Celiac ganglion L2 Lung Liver and gallbladder Stomach White rami communicantes Sacral splanchnic nerves Superior mesenteric ganglion Inferior mesenteric ganglion Spleen Adrenal medulla Kidney Lumbar splanchnic nerves Small intestine Large intestine Rectum Preganglionic Postganglionic Genitalia (uterus, vagina, and penis) and urinary bladder © 2013 Pearson Education, Inc. Dual Innervation • Both Divisions at once • can be as Autonomic plexuses • Nerve networks • sympathetic postganglionic fibers + • parasympathetic preganglionic fibers Several plexuses Autonomic Plexuses and Ganglia -heart Cardiac plexus So why does dual enervation work? Dual Innervation • nerves always on • Autonomic Tone • Background level 0 0 0 0 Dual Innervation • Heart Dual Innervation • opposing effects on heart function 1. Parasympathetic division • Acetylcholine à • increases hyperpolarization (IPSPs)à • slows heart rate 2. Sympathetic division • NE à heart rate • increases depolarization (EPSPs)à • increase heart rate • typically both neurotransmitters continuously Dual Innervation • If a crisis accelerates heart rate by: • Stimulation of sympathetic innervation • Inhibition of parasympathetic innervation
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