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The Nervous System
Divisions of the Nervous System
Nervous System
Peripheral
Nervous System
Somatic Nervous
System
Central Nervous
System
Autonomic
Nervous System
Sympathetic
Spinal Cord
Parasympathetic
Brain
Central Nervous System
• Includes the brain and spinal cord
• Is where sensory information is received and
motor (movement) control is initiated
• Protected by
– bone
• Brain – skull
• Spinal cord – vertebrae
– 3 protective membranes called meninges
• Space between meninges is cerebrospinal fluid
(cushions and protects)
The Brain
• Brain weighs about 3 pounds
• Has hundreds of billions of neurons
• You had the maximum number of neurons
when you were born
• 1000’s of neurons are lost every day and are
never replaced
• Don’t notice this until later in life when the
loss is so large
– This is why elderly people often become forgetful
The unconscious brain – parts of the
brain that work without us thinking
about them
• Medulla oblongata
– Closest to spinal cord
– Controls heart rate, breathing, bp, reflex reactions
(coughing, sneezing, vomiting, hiccupping, swallowing)
• Thalamus
– Receives sensory information (except for smell) from all
parts of the body
– Sends this info to the cerebrum for further processing
• Cerebellum
– Balance and complex muscular movement/coordination
– Butterfly shaped
– Receives sensory info from inner ear
• hypothalamus
– Regulation of homeostasis
– Maintains internal environments
– Detects hunger, sleep, thirst, body temp, water
balance, bp
– Controls the pituitary gland
• Link between nervous system and endocrine (hormone)
system
– Responsible for fight or flight response
– Pleasure centers located here
• corpus callosum
– Horizontal connecting piece between 2 halves of the
brain
– Transmits info between the right and left cerebral
hemispheres
The conscious brain – The cerebrum
• Largest most prominent, most highly developed
part of the brain
• Intellect, learning, memory and sensations are
formed here
• Divided into the right and left cerebral
hemispheres
– Right hemisphere controls the LEFT side of the body
– Left hemisphere controls the RIGHT side of the body
• Left Brain Right Brain Test
What each hemisphere does
Left Hemisphere
Right hemisphere
“logical side”
“Intuitive side”
Speaks
Creates images
Process data
Processes senses
Evaluates
Symbolizes
Analyzes differences
Seeks similarities
Is factual
Is spiritual
Is structured
Is spontaneous
Has time and measures
Has no time and measures
Speaks but cannot know
Knows but cannot speak
Talking
Feeling
Setting goals
Speculating
Planning
Visualizing
Measuring
Empathizing
Cerebral Lobes
• Frontal lobe: movement, higher intellectual
processing
– Problem solving, concentration, planning, judging
consequences
• Parietal lobe: sensations
– Touch, temperature, pressure, pain
– Understanding speech and using words
• Temporal lobe: hearing, smelling, interpreting
experiences
– Memory
• Occipital lobe: vision
Spinal Cord
• The “super highway” of the nervous system
• Contains central canal filled with cerebrospinal fluid
• Gray matter
–
–
–
–
Inner layer
Contains cell bodies of neurons
Looks like a butterfly with open wings
Cells bodies receive sensory information and send the motor
information where it needs to go
• White matter
– Outer layer
– Contains long fibers of internuerons bundled together in tracts
– Tracts connect spinal cord to brain