Chap15_2401 - 1 THE AUTONOMIC NERVOUS SYSTEM Chapter 15...

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1 THE AUTONOMIC NERVOUS SYSTEM Chapter 15 Anatomy and Physiology Lecture
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2 THE AUTONOMIC NERVOUS SYSTEM Autonomic Nervous System (ANS) regulates the activity of smooth muscles , cardiac muscles , and certain glands . -Structurally , the ANS includes two main components: (i) General visceral sensory (Afferent) neurons; and (ii) General visceral motor (Efferent) neurons. -Functionally , the ANS usually operates without conscious control. (The system was originally named autonomic because it was thought to function autonomously or in a self-governing manner, without control by the central nervous system (CNS). -ANS, however, is regulated by centers in the brain, mainly the hypothalamus and medulla oblongata . Contrasting the Somatic And Autonomic Nervous Systems Peripheral Nervous System (PNS) – Is composed of Sensory and Motor Neurons . Sensory Neurons – Carry action potentials from the peripheral to the central nervous system (CNS). Motor Neurons – Carry action potentials from the central nervous system (CNS) to the periphery.
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3 Two Subdivisions of the Motor Neurons : 1. Somatic Motor Neurons – Innervate skeletal muscles. 2. Autonomic Motor Neurons – Innervate smooth muscles, cardiac muscle, and glands. Organization of Somatic and Autonomic Nervous System Neurons Somatic Motor Pathway – Cell bodies are in the CNS and their axons extend from the CNS to skeletal muscle. Autonomic Motor Pathways – Consist of sets of two motor (efferent) neurons in series (one following the other). (1) The first ( preganglionic neuron ) has its cell body in the CNS; its axon extends from the CNS to an autonomic ganglion . Ganglion is a collection of neuronal cell bodies outside the CNS. (2) The second ( postganglionic neuron ) has its cell body in the Autonomic ganglion; its axon extends directly from the ganglion to the effector (smooth muscle, cardiac muscle, or gland). *Somatic Motor Neurons release Acetylcholine (ACh) as their neurotransmitter. *Autonomic Motor Neurons release either Acetylcholine (ACh) or Norepinephrine (NE). Note : Sensory neurons are not classified as somatic or autonomic. These neurons propagate action potentials from sensory receptors to the CNS and can provide information from reflexes mediated through the somatic nervous system or autonomic nervous system.
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4 Anatomy Of The Autonomic Nervous System Two Principal Divisions Of Autonomic Nervous System (ANS) : 1. Sympathetic Division 2. Parasympathetic Division Differences Between Sympathetic and Parasympathetic Divisions : 1. Location of their preganglionic neuron cell bodies within the CNS. 2. Location of their autonomic ganglia. Sympathetic Division Sympathetic division is sometimes called Thoracolumbar division because the cell bodies of sympathetic preganglionic neurons are in the lateral horns of the spinal cord gray matter between the first thoracic (T1) and the second lumbar (L2). Sympathetic chain ganglia
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This note was uploaded on 03/10/2012 for the course BIOL 2403 taught by Professor Campbell during the Spring '12 term at Texas Pan American.

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Chap15_2401 - 1 THE AUTONOMIC NERVOUS SYSTEM Chapter 15...

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