2007-2008AP Biology

Nervous Systems

Brain Development

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Nervous system

Central nervous system

Brain Spinal cord

Peripheral nervous system

Somatic (voluntary)

nervous system

Motor pathways

Sensory pathways

Autonomic (involuntary)

nervous system

Sympathetic division

Parasympathetic division

Sympatheticarousal & energy production“fight or flight”

Parasympatheticcalming & back to maintenance“rest & digest”

Sympatheticarousal & energy production“fight or flight”

Parasympatheticcalming & back to maintenance“rest & digest”

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Types of neurons

dendrites

sensory neuron cell body

axon

cell body

interneuron

cellbody

motor neuron

dendrites

“associative”

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Cephalization = Brain evolution

Cnidarian

nervenet

Simplest nervous system no control of complex actions

Simplest nervous systemno control of complex actions

More organizationbut still based on nerve nets; supports more complex movement

More organizationbut still based on nerve nets; supports more complex movement

Cephalization = clustering of neurons in “brain” at front (anterior) end of bilaterally symmetrical animalsCephalization = clustering of neurons in “brain” at front (anterior) end of bilaterally symmetrical animals

Flatworm Platyhelminthes

nerve cords

associativeneurons

Simplest, defined central nervous system more complex muscle control

Simplest, defined central nervous systemmore complex muscle control

Echinoderm

radial nervenerve

ribs

→→ where sense organs are

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Mollusk

brain

giantaxon brain

ventralnerve cords

Arthropod

Further brain development ganglia = neuron clusters along CNS

Further brain developmentganglia = neuron clusters along CNS

increase in interneurons in brain regionincrease in interneurons in brain region

Earthworm

central nervous system

peripheralnerves

More complex brainsconnected to all other parts of body by peripheral nerves

More complex brainsconnected to all other parts of body by peripheral nerves

More complex brains in predators most sophisticated invertebrate nervous system

More complex brains in predatorsmost sophisticated invertebrate nervous system

Cephalization = Brain evolution

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Evolution of vertebrate brain

Shark

Frog

Cat

Bird

HumanSpinal cordHind: Medulla oblongata

Optic tectumHind: Cerebellum

MidbrainFore: CerebrumOlfactory tract

Crocodile

hindbrain

↑forebrain

↑↑forebrain

↑↑↑forebrain dominant cerebrum

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Human brain

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Functional divisions of brainHindbrain

evolutionary older structures of the brainregulate essential autonomic & integrative functions

brainstemponsmedulla oblongatamidbrain

cerebellumthalamus, hypothalamus

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Brainstem The “lower brain”

medulla oblongataponsmidbrain

Functionshomeostasiscoordination of movementconduction of impulses to higher brain centers

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Medulla oblongata & PonsControls autonomic homeostatic functions

heart & blood vessel activitybreathingswallowingvomitingdigestion

Relays informationto & from higherbrain centers

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MidbrainInvolved in the integration of sensory information

regulation of visual reflexesregulation of auditory reflexes

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Reticular FormationSleep & wakefulness produces patterns of electrical activity in the brain

recorded as an ElectroEncephaloGram(EEG)most dreaming during REM(rapid eye movement) sleep

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Cerebrum Most highly evolved structure of mammalian brainCerebrum divided

hemispheresleft = right side ofbodyright = left side ofbody

Corpus callosummajor connectionbetween 2 hemispheres

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Lateralization of Brain FunctionLeft hemisphere

language, math, logic operations, processing of serial sequences of information, visual & auditory detailsdetailed activities requiredfor motor control

Right hemispherepattern recognition, spatialrelationships, non-verbalideation, emotionalprocessing, parallel processing of information

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Cerebrum specializationRegions of the cerebrum are specialized for different functionsLobes

frontaltemporaloccipitalparietal

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Limbic systemMediates basic emotions (fear, anger), involved in emotional bonding, establishes emotional memory

Amygdala involved in recognizing emotional content of facial expression

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Simplest Nerve CircuitReflex, or automatic response

rapid responseautomated

signal only goes to spinal cord

no higher level processing

adaptive valueessential actions don’t need to think or make decisions about

blinkingbalancepupil dilationstartle

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Eye Blink or Pain Withdrawal Reflex

Effector(muscle)

Spinalcord

InterneuronGraymatter

Whitematter

Motorneuron

Sensoryneuron

Receptorin skin

Stimulus

2007-2008AP Biology

cerebrumcerebellum

spinal cord cervicalnerves

thoracicnerves

lumbarnerves

femoral nerve

sciatic nerve

tibialnerve

Any Questions??