PY 105 Chapter Notes - Chapter 2: Central Nervous System, Reticular Formation, Peripheral Nervous System
Large Scale Functional Organization
• Peripheral nervous system can be subdivided into several functional divisions
o Somatic - concerned with conscious sensation and deliberate, voluntary movement of
skeletal muscle
o Autonomic - concerned with digestion, metabolism, circulation, perspiration and other
involuntary processes
• Includes both afferent and efferent functions
• Efferent is split into 2 subdivisions
o Sympathetic - "fight or flight"
o Parasympathetic - "rest and digest"
Anatomical Organization of Nervous System
• Central nervous system (CNS) - brain and spinal cord
• Peripheral nervous system (PNS) - all other axons, dendrites and cell bodies
• Greatest majority of neuronal cell bodies are found within CNS, bunched together called nuclei
• Somas located outside CNS known as ganglia
Central Nervous System Anatomical Organization
• Includes spinal cord and brain
• The brain has three subdivisions:
o Hindbrain (rhombencephalon)
o Midbrain (mesencephalon)
o Forebrain (prosencephalon)
• The entire CNS floats in cerebrospinal fluid (CSF), a clear liquid that serves various functions such
as shock absorption and exchange of nutrients and waste within the CNS
o Spinal cord is connected to the brain and protected by CSF
• It is a pathway for information to and from the brain
• Spinal cord is the site for information integration and processing
• Responsible for simple spinal reflexes
• Primitive processes such as walking, urination and sex organ function
o Hindbrain includes medulla, pons and cerebellum
• Medulla - located below pons and connects to spinal cord. Relays information
between other areas of the brain and regulates vital autonomic functions like blood
pressure
• Pons - below midbrain and above medulla. Connection point between brain stem and
cerebellum. Plays a role in balance and antigravity posture
• Cerebellum - behind pons and below cerebral hemisphere. Integrating center where
complex movements are coordinated. Damage results in poor hand-eye coordination
and balance
o Midbrain is a relay for visual and auditory information and contains the reticular activating
system (RAS) - arousal or wakefulness
o Brainstem - made up of medulla, pons and midbrain
• Contains processing centers and relays information to or from cerebellum and
cerebrum
o Forebrain - includes diencephalon and telencephalon
• Diencephalon includes thalamus and hypothalamus
▪ Thalamus - middle of the brain; contains relay and processing centers for
sensory information
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