PowerPoint Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College Ninth Edition Human Anatomy & Physiology C H A P T E R 14 Annie Leibovitz/Contact Press Images 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 Motor (efferent) division Somatic nervous system Autonomic nervous system (ANS) Sympathetic division Parasympathetic division Let s compare Somatic vs. Autonomic
Figure 14.2 Comparison of motor neurons in the somatic and autonomic nervous systems. Cell bodies in central nervous system Peripheral nervous system Neurotransmitter at effector Effector organs Effect SOMATIC NERVOUS SYSTEM Single neuron from CNS to effector organs Heavily myelinated axon ACh Skeletal muscle + Stimulatory Two-neuron chain from CNS to effector organs ACh NE AUTONOMIC NERVOUS SYSTEM SYMPATHETIC PARASYMPATHETIC Lightly myelinated preganglionic axons Lightly myelinated preganglionic axon ACh Ganglion Adrenal medulla Epinephrine and norepinephrine ACh Ganglion Nonmyelinated postganglionic axon Blood vessel Nonmyelinated postganglionic axon ACh Smooth muscle (e.g., in gut), glands, cardiac muscle + Stimulatory or inhibitory, depending on neurotransmitter and receptors on effector organs Acetylcholine (ACh) Norepinephrine (NE) So, how does this dual effect work?
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) α 1 : blood vessel constriction α 2 : pupil dilation Beta (β) β 1 : have one heart increase heart rate β 2 : have two lungs relax bronchiole smooth m. NE effects depend on subclass of receptor #s on target organ 2013 Pearson Education, Inc.
2013 Pearson Education, Inc. Roles
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 Sympathetic Eye Brain stem Eye TOP Salivary glands Cranial Skin* Heart Cervical Sympathetic ganglia Salivary glands Lungs Lungs MIDDLE Stomach T 1 Thoracic Heart Stomach Pancreas Pancreas L 1 Liver and gallbladder Liver and gallbladder Lumbar Adrenal gland BOTTOM Bladder Bladder 2013 Pearson Education, Inc. Genitals Sacral Genitals
Position of ganglia differs Parasympathetic : close to target organ Sympathetic close to spinal cord Parasympathetic Sympathetic So what? Think speed Sympathetic: fast, all-systems come on board So, what structures are enervated?
CN III CN VII CN IX CN X Ciliary ganglion Pterygopalatine ganglion Submandibular ganglion Otic ganglion Eye Lacrimal gland Nasal mucosa Submandibular and sublingual glands Parotid gland Cardiac and pulmonary plexuses Heart Lung Celiac plexus Liver and gallbladder Stomach Pancreas S 2 S 4 Large intestine Pelvic splanchnic nerves Inferior hypogastric plexus Rectum Small intestine Urinary bladder and ureters 2013 Pearson Education, Inc. Genitalia (penis, clitoris, and vagina) Preganglionic Postganglionic CN Cranial nerve S Sacral nerve
Eye Lacrimal gland Pons Nasal mucosa Superior cervical ganglion Sympathetic trunk (chain) ganglia Blood vessels; skin (arrector pili muscles and sweat glands) T 1 Middle cervical ganglion Inferior cervical ganglion Cardiac and pulmonary plexuses Salivary glands Heart Lung Greater splanchnic nerve Lesser splanchnic nerve Celiac ganglion Liver and gallbladder L 2 White rami communicantes Superior mesenteric ganglion Stomach Spleen Sacral splanchnic nerves Inferior mesenteric ganglion Lumbar splanchnic nerves Adrenal medulla Kidney Small intestine Large intestine Rectum Preganglionic Postganglionic 2013 Pearson Education, Inc. Genitalia (uterus, vagina, and penis) and urinary bladder
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