Chapter 3 The Anatomy of the Nervous System

Transcription

1 Chapter 3 The Anatomy of the Nervous System Systems, Structures, and Cells That Make Up Your Nervous System 1 General Layout of the Nervous System Central Nervous System (CNS) Brain (in the skull) Spinal Cord (in the spine) Peripheral Nervous System (PNS) Located outside of the skull and spine Serves to bring information into the CNS and carry signals out of the CNS 2 General Layout of the Nervous System Continued Peripheral Nervous System Somatic Nervous System Afferent nerves (sensory) Efferent nerves (motor) Autonomic Nervous System Sympathetic and parasympathetic nerves Both are efferent 3 1

2 FIGURE 3.2 The major divisions of the nervous system. 4 Autonomic Nervous System All nerves are efferent Sympathetic and parasympathetic nerves generally have opposite effects Two-stage neural paths, neuron exiting the CNS synapses on a second-stage neuron before the target organ 5 CourseSmart - Instructors - Print 1/23/12 1:42 PM User name: Robert Crutcher Book: Biopsychology, Eighth Edition Page: 491. No part of any book may be reproduced or transmitted by any means without the publisher's prior permission. Use (other than qualified fair use) in violation of the law or Terms of Service is prohibited. Violators will be prosecuted to the full extent of the law. Autonomic Nervous system 6 Page 2 of 7 2

3 User name: Robert Crutcher Book: Biological Psychology: An Introduction to Behavioral, Cognitive, and Clinical Neuroscience, Sixth Edition Page: 39. No part of any book may be reproduced or transmitted by any means without the publisher's prior permission. Use (other than qualified fair use) in violation of the law or Terms of Service is prohibited. Violators will be prosecuted to the full extent of the law. Autonomic Nervous System Continued Sympathetic Thoracic and lumbar Fight or flight Second stage neurons are far from the target organ Parasympathetic Cranial and sacral Rest and restore Second stage neurons are near the target organ 7 CourseSmart - Instructors - Print Autonomic Nervous System 2 1/28/12 9:55 PM 8 Page 7 of 10 Meninges, Ventricles, and Cerebrospinal Fluid (CSF) CNS encased in bone and covered by three meninges Dura mater tough outer membrane Arachnoid membrane web-like Pia mater adheres to CNS surface Cerebrospinal fluid (CSF) Fluid serves as cushion 9 3

4 FIGURE 3.3 The cerebral ventricles. 10 Protecting the Brain Chemical protection The blood-brain barrier tightly-packed cells of blood vessel walls prevent entry of many molecules Physical protection Skull Meninges Cerebrospinal fluid (CSF) 11 Absorption of cerebrospinal fluid from the subarachnoid space (blue) into a major sinus. 12 4

5 Cells of the Nervous System: Anatomy of Neurons Neurons Specialized cells for the reception, conduction, and transmission of electrochemical signals Many sizes and shapes 13 FIGURE 3.5 The major external features of a typical neuron. 14 FIGURE 3.6 The major internal features of a typical neuron. 15 5

6 FIGURE 3.7 The cell membrane is a lipid bilayer with signal proteins and channel proteins embedded in it. 16 FIGURE 3.8 A unipolar neuron, a bipolar neuron, a multipolar neuron, and an interneuron. 17 Glial Cells: The Forgotten Cells Glial cells Outnumber neurons 10:1 Support neurons Recent evidence for glial communication and modulatory effects of glia on neuronal communication Four classes of Glial cells: Oligodendrocytes extensions rich in myelin create myelin sheaths in CNS Schwann cells similar to function of oligodendrocytes but in PNS, can guide axonal regeneration Astrocytes largest glia, star-shaped, many functions Microglia involved in response to injury or disease 18 6

7 FIGURE 3.9 The myelination of CNS axons by an oligodendrocyte and the myelination of PNS axons by Schwann cells. 19 Terminology Note Myelin-providing glia CNS Oligodendrocytes PNS Schwann cells Clusters of cell bodies Nuclei (singular nucleus) Ganglia (singular ganglion) Bundles of axons Tracts Nerves 20 Neuroanatomical Techniques and Directions Golgi stain allows for visualization of individual neurons Nissl stain selectively stains cell bodies Electron microscopy provides information about the details of neuronal structure 21 7

8 FIGURE 3.11 Neural tissue that has been stained by the Golgi method. (Ed Reschke Peter Arnold, Inc.) 22 FIGURE 3.12 The Nissl stain. (Courtesy of Carl Ernst and Brian Christie, Department of Psychology, University of British Columbia.) 23 FIGURE 3.13 A color-enhanced scanning electron micrograph of a neuron cell body (green) studded with terminal buttons (orange). Courtesy of Jerold J. M. Chun, M.D., Ph.D. 24 8

9 Neuroanatomical Tracing Techniques Anterograde (forward) tracing to where axons project away from an area Retrograde (backward) tracing from where axons are projecting into an area 25 FIGURE 3.14 Anatomical directions in a representative vertebrate (cat). 26 FIGURE 3.15 Anatomical directions in a human. 27 9

10 Directions in the Vertebrate Nervous System Continued Anatomical directions ignore the fact that humans walk upright. Therefore, top of the head is both dorsal (back) and superior (top) Other directions: Medial toward the middle Lateral toward the side Proximal close Distal far 28 Sections of the Brain Horizontal a slice parallel to the ground Frontal (coronal) slicing bread or salami Sagittal a midsagittal section separates the left and right halves 29 FIGURE 3.16 Horizontal, frontal (coronal), and sagittal planes in the human brain and a cross section of the human spinal cord

11 CourseSmart - Instructors - Print 1/28/12 9:55 PM User name: Robert Crutcher Book: Biological Psychology: An Introduction to Behavioral, Cognitive, and Clinical Neuroscience, Sixth Edition Page: 42. No part of any book may be reproduced or transmitted by any means without the publisher's prior permission. Use (other than qualified fair use) in violation of the law or Terms of Service is prohibited. Violators will be prosecuted to the full extent of the law. 3 Views of the Brain 31 Page 10 of 10 Spinal Cord Gray matter inner component, primarily cell bodies White matter outer area, mainly myelinated axons Dorsal afferent, sensory Ventral efferent, motor 32 FIGURE 3.17 The dorsal and ventral roots of the spinal cord. FIGURE 3.18 A schematic cross section of the spinal cord

12 FIGURE 3.19 The early development of the mammalian brain illustrated in schematic horizontal sections. 34 FIGURE 3.20 The divisions of the adult human brain. 35 Major Structures of the Brain Myelencephalon = medulla Composed largely of tracts Origin of the reticular formation Metencephalon Many tracts Pons ventral surface Cerebellum coordination 36 12

13 FIGURE 3.21 Structures of the human myelencephalon (medulla) and metencephalon. 37 Major Structures of the Brain Continued Mesencephalon = midbrain tectum has inferior and superior colliculi tegmentum has periaqueductal gray, substantia nigra, and red nucleus Diencephalon thalamus hypothalamus 38 FIGURE 3.22 The human mesencephalon (midbrain)

14 FIGURE 3.23 The human diencephalon. 40 CourseSmart - Instructors - Print 1/23/12 1:42 PM User name: Robert Crutcher Book: Biopsychology, Eighth Edition Page: 495. No part of any book may be reproduced or transmitted by any means without the publisher's prior permission. Use (other than qualified fair use) in violation of the law or Terms of Service is prohibited. Violators will be prosecuted to the full extent of the law. Nuclei of the Thalamus 41 Telencephalon Cerebral Cortex Page 6 of 7 Convolutions serve to increase surface area Longitudinal fissure a groove that separates right and left hemispheres Corpus callosum largest hemisphere-connecting tract 42 14

15 FIGURE 3.25 The major fissures of the human cerebral cortex. 43 FIGURE 3.26 The lobes of the cerebral hemishphere. 44 Telencephalon Subcortical Structures Limbic system regulation of motivated behaviors Mammillary bodies, hippocampus, amygdala, fornix, cingulate, septum Basal ganglia motor system Amygdala, striatum (caudate nucleus + putamen), globus pallidus 45 15

16 FIGURE 3.28 The major structures of the limbic system: amygdala, hippocampus, cingulate cortex, fornix, septum, and mammillary body. 46 FIGURE 3.29 The basal ganglia: amygdala, striatum (caudate plus putamen) and globus pallidus. 47 FIGURE 3.30 Summary of major brain structures

17 CourseSmart - Instructors - Print 1/28/12 9:56 PM User name: Robert Crutcher Book: Biological Psychology: An Introduction to Behavioral, Cognitive, and Clinical Neuroscience, Sixth Edition Page: 43. No part of any book may be reproduced or transmitted by any means without the publisher's prior permission. Use (other than qualified fair use) in violation of the law or Terms of Service is prohibited. Violators will be prosecuted to the full extent of the law. Divisions of the Human Nervous System in Embryo and Adult 49 Page 1 of 10 17