© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE NERVOUS SYSTEM: INTRODUCTION, SPINAL CORD, AND SPINAL NERVES Chapter 10

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction Control center and communication network –Directs functions of body’s organs and systems –Interprets external environment –Determines reaction to change

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction (cont’d.) Homeostasis: balanced internal environment –Controlled by nervous and endocrine systems

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. ORGANIZATION

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Organization (cont’d.) Central nervous system: brain and spinal cord Peripheral nervous system –Afferent peripheral system Sensory neurons –Efferent peripheral system Somatic Autonomic - sympathetic and parasympathetic

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Organization (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. CLASSIFICATION OF NERVE CELLS

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Neuroglia Cells Astrocytes: support, connection, blood brain barrier Oligodendroglia: support, myelin sheath formation Microglial: phagocytosis Ependymal: line the ventricles of the brain

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Neuroglia Cells (cont’d.) Schwann: myelin sheaths in peripheral nervous system

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Structure of a Neuron Cell body Dendrites: receptive areas Axon: extension of cell body –Schwann cells –Nodes of Ranvier

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Structure of a Neuron (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Structure of a Neuron (cont’d.) Multipolar: several dendrites coming off cell body Bipolar: one dendrite and one axon Unipolar: one process extending from cell body

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Structure of a Neuron (cont’d.) Receptors: detect environmental stimuli Sensory: receive impulse from receptor site Internuncial: transmit impulse for interpretation and processing Motor: reaction to the stimulus

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE PHYSIOLOGY OF THE NERVE IMPULSE

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Physiology of the Nerve Impulse (cont’d.) Nerve cell fiber resting potential –Na + concentration higher on outside –K + concentration higher on inside –Negative charge on inside –Positive charge on outside

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Physiology of the Nerve Impulse (cont’d.) Depolarization: Na + rush inside cell Repolarization: K + rush out to restore balance Depolarization: Repolarization moves in one direction Myelinated vs. unmyelinated All-or-none law

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE SYNAPTIC TRANSMISSION

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Synaptic Transmission (cont’d.) Synapse: axon terminal branches close to next dendrites Impulse reaches axon terminals Triggers neurotransmitter release into synaptic cleft

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Synaptic Transmission (cont’d.) Neurotransmitters –Acetylcholine Most common –Epinephrine –Norepinephrine –Serotonin –Dopamine –Endorphins

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Animation – Firing of Neurotransmitters This animation illustrates the physiology of the nerve impulse Click Here to Play Firing of Neurotransmitters Animation

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE REFLEX ARC

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Reflex Arc (cont’d.) Knee-jerk reflex Maintain homeostasis –Heartbeat/breathing rates –Digestion –Coughing –Sneezing

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Reflex Arc (cont’d.) Maintain homeostasis –Swallowing –Vomiting

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Reflex Arc (cont’d.) Involuntary reaction to external stimulus

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. GROUPING OF NEURAL TISSUE

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Grouping of Neural Tissue (cont’d.) White matter –Groups of myelinated axons –Forms nerve tracts in CNS Gray matter –Nerve cell bodies and dendrites –Unmyelinated axon bundles –Cortex: gray matter on surface of brain

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Grouping of Neural Tissue (cont’d.) Nerve: bundle of fibers outside CNS Ganglia: nerve cell bodies outside CNS Tract: bundle of fibers inside CNS Nucleus: nerve cell bodies and dendrites inside CNS Horns: areas of gray matter in spinal cord

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE SPINAL CORD

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction Continuation of medulla oblongata 31 segments each with pair of spinal nerves Protected by meninges –Dura mater –Arachnoid –Pia mater

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Spinal Cord

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Functions of the Spinal Cord Conveys sensory impulses to the brain Integrates reflexes Spinal nerves connect at roots –Dorsal root: sensory –Ventral root: motor

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. THE SPINAL NERVES

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Spinal Nerves (cont’d.) All 31 pairs arise from union of dorsal and ventral roots Mixed nerves consisting of motor and sensory fibers Most exit vertebral column between vertebrae

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Spinal Nerves (cont’d.) Named and numbered according to region and level of spinal cord –Cervical: 8 pairs –Thoracic: 12 pairs –Lumbar: 5 pairs –Sacral: 5 pairs –Coccygeal: 1 pair

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary Named the major division of the nervous system Classified neurons and neuroglial cells Discussed the physiology of the nerve impulse and transmission at synapses Named the different types of neural tissue

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary (cont’d.) Discussed the structure of the spinal cord Named the spinal nerves