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Nervous System: Part 2Nervous System: Part 2
Organization of the Nervous SystemOrganization of the Nervous SystemThe SensesThe Senses
Nervous System OrganizationNervous System Organization
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
spinal cordbrain
Sensory nervescarry sensory informationinto brain and spinal cord
Motor nervescarry motor informationfrom CNS to effectors
somatic sensorynerves: signals
from skin,muscles,
joints, specialsenses
visceral sensorynerves:
signals frombody organs
Somatic motornerves: signals
to skeletalmuscles,
voluntary
Autonomic motor nerves:
signals to smoothmuscle, cardiacmuscle, glands,
involuntary
Sympatheticdivision
“fight or flight”
Parasympatheticdivision
“rest and digest”
Parts of the BrainParts of the Brain
musclecoordination
Cortex: thinking, learning, memory, speech movement,
senses
breathing, heart rate, blood pressure
sends sensory input to cerebrum
homeostasis
Spinal Cord Spinal Cord and Reflex Arcsand Reflex Arcs
white matter
ventral root
axon of motor neuron
axon of sensory neuron
cell body of sensory neuron
pin
dorsal root ganglion
cell body of interneuron
Dorsalgray matter
central canal
ventral horn
sensoryreceptor(in skin)
effector(muscle)
cell body ofmotor neuron
Ventral
dorsalhorn
Involve the Somatic Nervous System
Autonomic Nervous SystemAutonomic Nervous System
dilates pupilsconstricts
pupils
speeds heart slows heart
dilates air passages
constricts bronchioles
decreases stomach and
intestinal activity
increases stomach and
intestinal activity
Nervous System Case Study: Nervous System Case Study: HemimegalenchephalyHemimegalenchephaly
• Dylan Catania was born with an oversized right Dylan Catania was born with an oversized right hemisphere in his brain that was causing constant hemisphere in his brain that was causing constant seizuresseizures
• His only hope of survival and brain development His only hope of survival and brain development involved early surgery to sever the connections involved early surgery to sever the connections between the right and left hemispheres of the brainbetween the right and left hemispheres of the brain
Nervous System Case Study: Nervous System Case Study: HemimegalenchephalyHemimegalenchephaly
Nervous System Case Study: Nervous System Case Study: Surgery for HemimegalenchephalySurgery for Hemimegalenchephaly
Nervous System Case Study: Nervous System Case Study: Surgery for HemimegalenchephalySurgery for Hemimegalenchephaly
Nervous System Case Study: Nervous System Case Study: HemimegalenchephalyHemimegalenchephaly
Dylan has been seizure free Dylan has been seizure free since his surgery!since his surgery!
Sensation and PerceptionSensation and Perception
Sensation: impulses arrive
at cerebral cortex
Perception: cortex interprets
meaning of sensations
Sensory Areas on Cerebral CortexSensory Areas on Cerebral Cortex
Sense of Vision: Structure of the EyeSense of Vision: Structure of the Eyephotoreceptors
detect light
takes nerve impulses to
brain
focuses light on retina
lens
photoreceptors
Photoreceptors synapse with neurons that take signal to optic nerve
Sense of Vision: PhotoreceptorsSense of Vision: Photoreceptors
detects color detects light absorbs light,initiates series
of steps leading to nerve signal
Sense of Hearing: Sense of Hearing: Structure of the EarStructure of the Ear
1. Sound enters auditory canal
3. Ossicles (bones) of middle ear multiply pressure of vibration
4. Membrane-covered opening transfers pressure to inner ear
5. Pressure enters fluid-filled chamber containing mechanoreceptors
2. Eardrum vibrates slightly due to sound waves
Sense of Hearing: MechanoreceptorsSense of Hearing: Mechanoreceptors
Vibrates in response to pressure in
inner ear
mechanoreceptor
Bend when basilar membrane moves
takes nerve impulses to
brain
Sense of Taste: Sense of Taste: ChemoreceptorsChemoreceptors
Taste buds occur along the walls of
papillae
Molecules bind to receptors on
microvilli of taste cells
Nerve impulses are sent to brain
chemoreceptor
Signal from receptor is transmitted
within the cell
Sense of TasteSense of TasteSignal Transmission for Salty and Sour TastesSignal Transmission for Salty and Sour Tastes
Sodium binds and opens a channel for more sodium
to enter
Protons bind and open a channel
for more protons to enter
Release of calcium triggers
neurotransmitter release and neuron
stimulation
Sense of TasteSense of TasteSignal Transmission for Sweet and Bitter TastesSignal Transmission for Sweet and Bitter Tastes
Internal communication leads to neuron
stimulation