Lecture Human anatomy and physiology - Chapter 11: Fundamentals of the nervous system and nervous tissue (part a)

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This chapter students will be able to: List the basic functions of the nervous system; explain the structural and functional divisions of the nervous system; list the types of neuroglia and cite their functions; define neuron, describe its important structural components, and relate each to a functional role;...

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Nội dung Text: Lecture Human anatomy and physiology - Chapter 11: Fundamentals of the nervous system and nervous tissue (part a)

PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College CHAPTER 11 Fundamentals of the Nervous System and Nervous Tissue: Part A Copyright © 2010 Pearson Education, Inc.
Functions of the Nervous System 1. Sensory input • Information gathered by sensory receptors about internal and external changes 2. Integration • Interpretation of sensory input 3. Motor output • Activation of effector organs (muscles and glands) produces a response Copyright © 2010 Pearson Education, Inc.
Sensory input Integration Motor output Copyright © 2010 Pearson Education, Inc. Figure 11.1
Divisions of the Nervous System • Central nervous system (CNS) • Brain and spinal cord • Integration and command center • Peripheral nervous system (PNS) • Paired spinal and cranial nerves carry messages to and from the CNS Copyright © 2010 Pearson Education, Inc.
Peripheral Nervous System (PNS) • Two functional divisions 1. Sensory (afferent) division • Somatic afferent fibers—convey impulses from skin, skeletal muscles, and joints • Visceral afferent fibers—convey impulses from visceral organs 2. Motor (efferent) division • Transmits impulses from the CNS to effector organs Copyright © 2010 Pearson Education, Inc.
Motor Division of PNS 1. Somatic (voluntary) nervous system • Conscious control of skeletal muscles Copyright © 2010 Pearson Education, Inc.
Motor Division of PNS 2. Autonomic (involuntary) nervous system (ANS) • Visceral motor nerve fibers • Regulates smooth muscle, cardiac muscle, and glands • Two functional subdivisions • Sympathetic • Parasympathetic Copyright © 2010 Pearson Education, Inc.
Central nervous system (CNS) Peripheral nervous system (PNS) Brain and spinal cord Cranial nerves and spinal nerves Integrative and control centers Communication lines between the CNS and the rest of the body Sensory (afferent) division Motor (efferent) division Somatic and visceral sensory Motor nerve fibers nerve fibers Conducts impulses from the CNS Conducts impulses from to effectors (muscles and glands) receptors to the CNS Somatic sensory Somatic nervous Autonomic nervous fiber system system (ANS) Skin Somatic motor Visceral motor (voluntary) (involuntary) Conducts impulses Conducts impulses from the CNS to from the CNS to skeletal muscles cardiac muscles, Visceral sensory fiber smooth muscles, Stomach and glands Skeletal muscle Motor fiber of somatic nervous system Sympathetic division Parasympathetic Mobilizes body division systems during activity Conserves energy Promotes house- keeping functions during rest Sympathetic motor fiber of ANS Heart Structure Function Sensory (afferent) division of PNS Parasympathetic motor fiber of ANS Bladder Motor (efferent) division of PNS Copyright © 2010 Pearson Education, Inc. Figure 11.2
Histology of Nervous Tissue • Two principal cell types 1. Neurons—excitable cells that transmit electrical signals Copyright © 2010 Pearson Education, Inc.
Histology of Nervous Tissue 2. Neuroglia (glial cells)—supporting cells: • Astrocytes (CNS) • Microglia (CNS) • Ependymal cells (CNS) • Oligodendrocytes (CNS) • Satellite cells (PNS) • Schwann cells (PNS) Copyright © 2010 Pearson Education, Inc.
Astrocytes • Most abundant, versatile, and highly branched glial cells • Cling to neurons, synaptic endings, and capillaries • Support and brace neurons Copyright © 2010 Pearson Education, Inc.
Astrocytes • Help determine capillary permeability • Guide migration of young neurons • Control the chemical environment • Participate in information processing in the brain Copyright © 2010 Pearson Education, Inc.
Capillary Neuron Astrocyte (a) Astrocytes are the most abundant CNS neuroglia. Copyright © 2010 Pearson Education, Inc. Figure 11.3a
Microglia • Small, ovoid cells with thorny processes • Migrate toward injured neurons • Phagocytize microorganisms and neuronal debris Copyright © 2010 Pearson Education, Inc.
Neuron Microglial cell (b) Microglial cells are defensive cells in the CNS. Copyright © 2010 Pearson Education, Inc. Figure 11.3b
Ependymal Cells • Range in shape from squamous to columnar • May be ciliated • Line the central cavities of the brain and spinal column • Separate the CNS interstitial fluid from the cerebrospinal fluid in the cavities Copyright © 2010 Pearson Education, Inc.
Fluid-filled cavity Ependymal cells Brain or spinal cord tissue (c) Ependymal cells line cerebrospinal fluid-filled cavities. Copyright © 2010 Pearson Education, Inc. Figure 11.3c
Oligodendrocytes • Branched cells • Processes wrap CNS nerve fibers, forming insulating myelin sheaths Copyright © 2010 Pearson Education, Inc.
Myelin sheath Process of oligodendrocyte Nerve fibers (d) Oligodendrocytes have processes that form myelin sheaths around CNS nerve fibers. Copyright © 2010 Pearson Education, Inc. Figure 11.3d
Satellite Cells and Schwann Cells • Satellite cells • Surround neuron cell bodies in the PNS • Schwann cells (neurolemmocytes) • Surround peripheral nerve fibers and form myelin sheaths • Vital to regeneration of damaged peripheral nerve fibers Copyright © 2010 Pearson Education, Inc.