The Nervous System

Divisions of the Nervous System Nervous System

Peripheral Nervous System

Somatic Nervous System

Autonomic Nervous System

Sympathetic Parasympathetic

Central Nervous System

Spinal Cord 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