The Nervous System

Divisions of the Nervous System Nervous System Peripheral Nervous System Somatic Nervous System Autonomic Nervous System SympatheticParasympathetic Central Nervous System Spinal CordBrain

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 HemisphereRight hemisphere “logical side”“Intuitive side” SpeaksCreates images Process dataProcesses senses EvaluatesSymbolizes Analyzes differencesSeeks similarities Is factualIs spiritual Is structuredIs spontaneous Has time and measuresHas no time and measures Speaks but cannot knowKnows but cannot speak TalkingFeeling Setting goalsSpeculating PlanningVisualizing MeasuringEmpathizing

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