the systems, structures, and cells that make up your nervous system chapter 3 the anatomy of the...
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The Systems, Structures, and Cells That Make Up Your Nervous System
Chapter 3The Anatomy of the Nervous System
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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
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Major divisions of the nervous system
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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
Meningeshttp://faculty.une.edu/com/fwillard/Meninges/pages/mening02.htm
http://faculty.une.edu/com/fwillard/Meninges/pages/mening02.htm
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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)
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Cells of the Nervous System Neurons
Specialized cells for the reception, conduction, and transmission of electrochemical signals
Many sizes and shapes Glial cells
Outnumber neurons 10:1
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Major external features of
a typical neuron
Cells of theNervousSystem
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The cell
mem-brane
Cells of the Nervous System (continued)
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Cells of the Nervous System (continued)
Fourtypes
ofneurons
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Glial Cells: The Forgotten Majority
Four classes: 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
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Terminology NoteCNS PNS
Myelin-providing glia
Oligodendrocytes Schwann cells
Clusters of cell bodies
Nuclei (singular nucleus)
Ganglia(singular ganglion)
Bundles of axons Tracts Nerves
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Neuroanatomical Techniques Golgi stain – allows for
visualization of individual neurons
Nissl stain – selectively stains cell bodies
Electron microscopy – provides information about the details of neuronal structure
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Neuroanatomical Tracing Techniques
Anterograde (forward) tracing where axons project
away from an area Retrograde (backward)
tracing where axons are projecting into an area
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Directions in the Vertebrate Nervous System
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Directions in the Vertebrate Nervous System (continued)
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Directions in the Vertebrate Nervous System (continued)
Anatomical directions ignore the fact that humans walk upright. Therefore, top of the head both “dorsal” (back) and “superior” (top)
Other directions: Medial – toward the middle Lateral – toward the side Proximal – close Distal – far
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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
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The Spinal Cord Gray matter – inner component,
primarily cell bodies White matter – outer area, mainly
myelinated axons Dorsal – afferent, sensory Ventral – efferent, motor
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The Spinal Cord (continued)
Dorsal and ventral roots Spinal cross section
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The Five Major Divisions of the Brain
Early develop-
ment of themammalian
brain
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The Five Major Divisions of the Brain (continued)
The divisionsof the adult
human brain
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Major Structures of the Brain Myelencephalon = medulla
Composed largely of tracts Origin of the reticular formation
Metencephalon Many tracts Pons – ventral surface Cerebellum – coordination
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Structures of thehuman
myelencephalon(medulla) and
metencephalon
Major Structures of the Brain
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Major Struc-tures of theBrain (continued)
The humanmesencephalon
(midbrain)
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(continued)
Major Structures of the Brain
The humandiencephalon
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Telencephalon – Cerebral Cortex Convolutions serve to increase
surface area Longitudinal fissure – a groove
that separates right and left hemispheres
Corpus callosum – largest hemisphere-connecting tract
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Major fissures of the cerebral hemispheres Lobes of the cerebral hemispheres
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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
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The major structures of
the limbicsystem
Telencephalon – Subcortical Structures
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The basal ganglia
Telencephalon – Subcortical Structures
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Summary of major brain structures