2007-2008 AP Biology

Nervous Systems

Brain Development

AP Biology

Nervous system

Centralnervoussystem

BrainSpinalcord

Peripheralnervoussystem

Somatic(voluntary)

nervous system

Motorpathways

Sensorypathways

Autonomic(involuntary)

nervous system

Sympatheticdivision

Parasympatheticdivision

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 systemno 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 animals

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

FlatwormPlatyhelminthes

nerve cords

associativeneurons

Simplest, defined central nervous systemmore 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 developmentganglia = neuron clusters along CNS

Further brain developmentganglia = neuron clusters along CNS

increase in interneurons in brain region increase 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 predatorsmost 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 cord

Hind: Medulla oblongata

Optic tectum

Hind: Cerebellum

MidbrainFore: CerebrumOlfactory tract

Crocodile

hindbrain

forebrain

forebrain

forebraindominant cerebrum

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Human brain

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Functional divisions of brain Hindbrain

evolutionary older structures of the brain regulate essential autonomic & integrative

functions brainstem

pons medulla oblongata midbrain

cerebellum thalamus, hypothalamus

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Brainstem The “lower brain”

medulla oblongata pons midbrain

Functions homeostasis coordination of movement conduction of impulses to higher brain

centers

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Medulla oblongata & Pons Controls autonomic homeostatic

functions heart & blood vessel activity breathing swallowing vomiting digestion

Relays information to & from higher brain centers

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Midbrain Involved in the integration of sensory

informationregulation of

visual reflexesregulation of

auditory reflexes

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Reticular Formation Sleep & 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 brain Cerebrum divided

hemispheres left = right side of

body right = left side of

body Corpus callosum

major connection between 2 hemispheres

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Lateralization of Brain Function Left hemisphere

language, math, logic operations, processing of serial sequences of information, visual & auditory details

detailed activities required for motor control

Right hemisphere pattern recognition, spatial

relationships, non-verbal ideation, emotional processing, parallel processing of information

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Cerebrum specialization Regions of the cerebrum are

specialized for different functions Lobes

frontal temporal occipital parietal

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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 Circuit Reflex, or automatic response

rapid response automated

signal only goes to spinal cord no higher level

processingadaptive value

essential actions don’t need to think or

make decisions about blinking balance pupil dilation startle

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Eye Blink or Pain Withdrawal Reflex

Effector(muscle)

Spinalcord

InterneuronGraymatter

Whitematter

Motorneuron

Sensoryneuron

Receptorin skin

Stimulus

2007-2008 AP Biology

cerebrum

cerebellum

spinal cord cervicalnerves

thoracicnerves

lumbarnerves

femoral nerve

sciatic nerve

tibialnerve

Any Questions??