Nervous System Chapter 13 PDF

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HospitablePopArt5851

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Georgia Gwinnett College

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nervous system neurobiology physiology anatomy

Summary

This document provides an overview of the nervous system, including its functions, divisions, and components. It details the neuroanatomy and neurophysiology of neurons, illustrating the workings of the nervous system at both a structural and functional level.

Full Transcript

Chapter 13 Nervous System 1 Nervous System Overview Neurobiology – study of nervous system – Includes neuroanatomy and neurophysiology Nervous system functions include sensory perception (organized and interpreted), integration (combining information), motor planning...

Chapter 13 Nervous System 1 Nervous System Overview Neurobiology – study of nervous system – Includes neuroanatomy and neurophysiology Nervous system functions include sensory perception (organized and interpreted), integration (combining information), motor planning (output) Two main divisions – Central nervous system (CNS) is brain and spinal cord – Peripheral nervous system (PNS) is nerves and ganglia 13-2 Nervous System Overview 13-3 Peripheral Nervous System Sensory Division = from receptors to CNS – Somatic = signals from skin, muscle, bones and joints – Visceral = signals from thoracic and abdominal cavities Motor Division = from CNS to glands and muscles – Somatic = signal to skeletal muscle – Visceral = signal to glands, cardiac and smooth muscle Sympathetic = arouse the body Parasympathetic = energy intake and conservation 13-4 Neurons Nerve cell = neuron Fundamental physiological (Universal) properties 1. Excitability (irritability) – can respond to stimuli 2. Conductivity – can send signals to distant locations quickly 3. Secretion – can release chemical messengers (neurotransmitters) 13-5 Functional Classes of Neurons Sensory (afferent) neurons – detect stimuli Interneurons (association neurons) – receive signals and makes decisions about response Motor (efferent) neurons – send signals to muscles to provide response 13-6 Structure of a Neuron Neurosoma (soma or cell body) control center Nissl bodies contain compartmentalized rough ER Dendrites receive signals Axon sends action potentials – Synaptic knob (terminal button) – ending of axon branch that communicates with another cell 13-7 Neuroglia “glial cells” Outnumber neurons 10 to 1 Support cells – Protect and aid in function Glia means “glue” – Bind neurons together 13-8 Types of Neuroglia 1. CNS glia – Oligodendrocytes - myelinate to assist conduction Octopus-like with as many as 15 arm-like processes Each process spirals around the nerve fiber – Ependymal cells Cuboidal cells that line cavities of brain and spinal cord Secretes and circulates cerebral spinal fluid 13-9 Types of Neuroglia 1. CNS glia continued – Microglia – Small macrophages help in defense and disposal of debris and pathogens – Astrocytes Most abundant with many branches with ‘feet’ and star shaped provide supportive framework, create blood brain barrier provide and nourishment 13-10 Myelination of CNS Analagous to insulation on a wire Oligodendrocytes make fatty white matter of CNS Internodes – fiber segments covered by myelin Nodes of Ranvier – fiber segments with gaps in myelin 13-11 Synapses Meeting point of neuron and other cell Presynaptic neuron to postsynaptic neuron Communication is either – Chemical (neruotransmiters) – Electrical (ions) 13-12 Chemical Synapse Presynaptic neuron releases neurotransmitter to postsynaptic cell Neurotransmitters – messenger molecules – Some are excitatory, some are inhibitory – Acetylcholine (NMJ) – norepinephrine (sympathetic) – glutamate & aspartate (excitatory) – GABA & glycine (inhibitory) – dopamine, serotonin, histamine, >100 13-13 Chemical Synapse, continued Structures at a synapse: Synaptic knob of presynaptic cell Contains synaptic vesicles – packets of neurotransmitters Synaptic cleft Neurotransmitter receptors on postsynaptic cell 13-14 Electrical Synapse Connects Neurons, neuroglia, cardiac and smooth muscle cells Adjacent cells joined by gap junctions Ions diffuse from cell to cell Quick transmission – no delay at release and binding of neurotransmitter No integration or decision-making 13-15

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