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Chapter 2
Overview of the Nervous System
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Anatomical Directions Help Us Locate Structures in the Nervous System
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Anatomical Directions for a Four-Legged Animal
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In humans, the dorsal parts of our brain form a 90-degree angle with the dorsal parts of the spinal cord.
Anatomical Directions in a Two-legged Animal
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Planes of Section
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Basic Features of the Nervous System
Meninges:
Dura mater:
Arachnoid membrane:
Pia mater:
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Basic Features of the Nervous System
Ventricles: Hollow spaces within the brain. Each ventricle produces cerebrospinal fluid
(CSF). CSF supports the weight of the brain. Prevents pressure on neurons, which would lead
to false info Helps reduce shock to the CNS caused by sudden
head movements.
Choroid plexus: The highly vascular tissue that protrudes into
the ventricles and produces cerebrospinal fluid.
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Circulation of the Cerebrospinal Fluid
Four ventricles:
• 2 lateral ventricles
• 3rd ventricle
• 4th ventricle
Central canal of the spinal cord
Subarachnoid space
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The Brain’s Blood Supply
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In rest of body In brain
Blood-Brain Barrier (barrier #1)
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Blood-Brain Barrier (barrier #2)
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The Organization of the Nervous System
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The Spinal Cord
Functions:
The “information superhighway”
Protective withdrawal reflexes Patellar reflex
Postural reflexes
Divisions of the Brain
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Medulla Cerebellum Pons
Raphe Nuclei Locus Coeruleus
The Three Main Sections of the Brain: The Hindbrain
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Tectum:
Superior Colliculus
Interior Colliculus
Tegmentum:
Periaqueductal Gray
Substantia Nigra
The Three Main Sections of the Brain: The Midbrain
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Thalamus
Hypothalamus
The Three Main Sections of the Brain: The Forebrain - Diencephalon
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• Basal Ganglia
The Three Main Sections of the Brain: The Forebrain - Telencephalon
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The Three Main Sections of the Brain: The Forebrain - Telencephalon
Limbic System:
Hippocampus
Amygdala
Cingulate Cortex
(hypothalamus)
Septum
Olfactory Bulb
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• Cerebral Cortex
The Three Main Sections of the Brain: The Forebrain - Telencephalon
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Connections Between the Hemispheres The corpus callosum The anterior commissure
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The Cerebral Cortex II
Lobes: Frontal Parietal Occipital Temporal
Functions: Sensory Motor Association
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The Peripheral Nervous System
Autonomic nervous system: Controls the body’s vegetative functions. “fight or flight” response
Sympathetic division: Controls functions that accompany arousal and expenditure
of energy. Parasympathetic division:
Controls functions that occur during a relaxed state.
Somatic nervous system: Controls the movement of skeletal muscles or
transmits somatosensory information to the central nervous system.
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Autonomic Nervous System
• Sympathetic
•Parasympathetic
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Somatic Nervous System
The Cranial Nerves Twelve pairs of cranial nerves exit the brain. Provide sensory and motor functions to the
head and neck.
The Spinal Nerves 31 pairs exit the spinal cord Provide sensory and motor functions to the
torso, arms, and legs
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Cranial Nerves