Unit 2 Notes:

Nervous System Basics

Tuesday

2-23-2010

(1) Function

• Respond to stimuli

• Process information

• Communicate

• Maintain homeostasis

• Basic Pathway:Sensory Input Integrate & Process Motor Output

(2) Structure

• Made of:– Brain– Spinal cord– Neurons– Junctions

• Has a complex organization (hierarchy) of sensory and motor levels.

(3) Brain & Spine

• Brain divided into lobes

• Spinal cord = communication highway

• All nerves communicate through Spine

• Example: Paralysis

(4) Neuron• Neuron = Nerve Cell

• Types: Multipolar + Unipolar

• Basic Structural Components:– Dendrites (Incoming)– Cell Body (Integrate + Process)– Axon (Outgoing)–Myelin Sheath (Insulation + Speed)– Axon Terminal (Final Destination)

(5) Unipolar Neurons

• Use: Afferent Input (Sensory Input)

• Dendrites connected to sensory organ

• Message sent to cell body Out Axon

• Message sent out of axon terminal

• FOCUS:– Get message to CNS– Let CNS process and decide

(NO need to have cell body right by dendrites)

(6) Multipolar Neurons• Use: Efferent Output (Motor Output)

• Multi = Lots of extensions coming from cell body• Cell body directly connected to dendrites• Dendrites coming from CNS / Efferent path

effected organ

• FOCUS:– Organize messages by importance– Make organs do things

(Important to have cell body right next to dendrites)

(7) Junctions

• Junction = Meeting of Neuron + Neuron or Neuron + Organ– A.K.A. Synapse, Synaptic Cleft

• Nerve Impulse Axon Axon Terminal Release Neurotransmitter– Neurotransmitter = Chemical Message– Causes an effect– Binds with cell membrane on other side

(8) Nervous System Organization

CENTRAL NERVOUS SYSTEM

PERIPHERAL NERVOUS SYSTEM(SENSORY / AFFERENT INPUT)

PERIPHERAL NERVOUS SYSTEM(MOTOR / EFFERENT OUTPUT)

BODY(INITIAL STIMULUS

/ IMBALANCE)

AUTONOMIC(INVOLUNTARY)

SOMATIC(VOLUNTARY)

PARASYMPATHETIC(REST & DIGEST)

SYMPATHETIC(FIGHT / FLIGHT)

(9) Sensory Input

• Afferent Input (away from body)

• Sends message from body part Brain

• Initial stimulus or Imbalance

(10) Central Nervous System (CNS)

• INCLUDES: Brain & Spinal cord

• “Head Honcho”– Notified of everything, Makes all decisions

(11) Peripheral Nervous System (PNS)

• “Middle Man” / Body Guard: Body—CNS– Helps organize messages being sent to CNS

and to organs.

• 2 Divisions:– Sensory/Afferent Input–Motor/Efferent Output

(12) Motor / Efferent Output

• CNS Effector Organ– CNS makes decision– CNS sends message to release chemical, or

move– GOAL:GOAL: Regain Balance / Do What You Want

• 2 Divisions:– Autonomic Nervous System– Somatic Nervous System

(13) Somatic Nervous System

• Voluntary Actions

• Skeletal Muscle

• (All other actions are

involuntary)

(14) Autonomic Nervous System

• Involuntary Actions– Autonomic : Autopilot– Processes occur naturally without thought

• 2 Subdivisions:– Parasympathetic

Pathway– Sympathetic

Pathway

(15) Parasympathetic Pathway

• (Involuntary)

• “Rest & Digest”

• Normal bodily functions:– Digestion , Excretion– Lens Contraction, Blinking– Gas Exchange– Sleep

(16) Sympathetic Pathway

• (Involuntary)

• “Fight or Flight”

• Bodily Functions during heightened excitement:– Increased heart rate, respiration– Increased sweating– Increased blood flow