Download Central Nervous System

Chapter 2
The Anatomy of the Brain
The Systems, Structures, and
Cells that Make Up Your
Nervous System
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Copyright © 2007 by Allyn and Bacon
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
Copyright © 2007 by Allyn and Bacon
General Layout of the Nervous
System

PNS – 2 divisions
 Somatic


Nervous System
Afferent nerves (sensory)
Efferent nerves (motor)
 Autonomic

Nervous System
Sympathetic and parasympathetic nerves
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Autonomic Nervous System
Sympathetic
 “fight or flight”
 Second stage
neurons are far
from the target
organ

Parasympathetic
 “rest and restore”
 Second stage
neurons are near
the target organ

Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon
Meninges, Ventricles, and CSF

CNS - encased in bone and covered
by three meninges
 Dura
mater - tough outer membrane
membrane - weblike
 Pia mater - sticks to CNS surface
 Arachnoid

Cerebrospinal fluid (CSF)
 Fluid
serves as cushion
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Protecting the Brain

Chemical protection
blood-brain barrier – tightly-packed
cells of blood vessel (endothelial cells)
walls prevent entry of many molecules
 The

Physical protection
 Skull
 Meninges
 Cerebrospinal
fluid (CSF)
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Cells of the Nervous System
Generally two types
 Neurons – specialized for reception,
conduction, and transmission
 Glial cells – Support cells; outnumber
neurons by 10 to 1.

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Anatomy of Neurons
 Neurons




– structural classes
Multipolar
Unipolar
Bipolar
Interneurons
Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon
Anatomy of Neurons
 Nuclei
– clusters of cell bodies in the
CNS
 Ganglia – clusters of cell bodies in
the PNS
 Tracts – bundles of axons in the CNS
 Nerves – bundles of axons in the
PNS
Copyright © 2007 by Allyn and Bacon
Glial Cells: The Forgotten Majority
 Myelin
producers
Oligodendrocytes
(CNS)
Schwann cells (PNS)
– largest, many functions
(composed the blood-brain barrier)
 Microglia – smallest, involved in
response to injury or disease
 Astrocytes
Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon
Terminology Note
CNS
MyelinOligodendrocytes
providing glia
PNS
Schwann
Cells
Clusters of Nuclei
cell bodies (singular nucleus)
Ganglia
Bundles of Tracts
axons
Nerves
(singular ganglion)
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Neuroanatomical Directions
Anterior (rostral) – towards the nose
 Posterior (caudal) – towards the tail
 Dorsal – towards the surface of the back
or the top of the head
 Ventral – towards the surface of the
chest or the bottom of the head

Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon
The Five Divisions of the 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
Copyright © 2007 by Allyn and Bacon
Major Structures of the Brain

Mesencephalon
 Tectum
(dorsal surface)
Inferior colliculi – audition
Superior colliculi - vision
 Tegmentum
(ventral) – 3 ‘colorful’ structures
Periaqueductal gray – analgesia
Substantia nigra – sensorimotor
Red nucleus– sensorimotor
Copyright © 2007 by Allyn and Bacon
Major Structures of the Brain

Diencephalon
 Thalamus – sensory
 Hypothalamus



relay nuclei
Regulation of motivated behaviors
Controls hormone release by the pituitary
Telencephalon
 Cerebral cortex
 Limbic system
 Basal ganglia
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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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Limbic System
Regulation of motivated behaviors
 “a circuit of midline structures that circle
the thalamus”
 Consists of

 Primitive
cortex - hippocampus and cingulated
cortex
 Subcortical structures - mammillary bodies,
amygdala, fornix, septum
Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon
Copyright © 2007 by Allyn and Bacon