nervous & other systems
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Nervous Systems
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Nervous Systems
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Evolution of the Nervous
System
Nerve Net
Cnidarian, Ctenophora
Nerve Ring with radial nerves Echinodermata
Bilateral Nervous Systems
Cephalization (ganglia or brain) Nerve cord
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Evolution of the Nervous
System
Bilateral Nervous Systems
Ganglia and two or more longitudinal nerve
cords
platyhelminthes, some mollusca
Ganglia (brain) and ventral nerve cord
annelida, arthropoda, some mollusca
Brain and dorsal nerve cord chordata
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Overview of a Nervous
System
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Overview of a Nervous System
Sensory Input conduction of signals from sensory
receptors
PNS Integration
environmental information is interpreted
CNS (brain and spinal cord) Motor Output
conduction of signals to effector cells
PNS
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Neurons
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Neurons
Cell body
nucleus and organelles
Dendrites short and branched
toward cell body
Axons long and unbranched
away from cell body
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Axons
Myelin Sheath - insulating layer
Node of Ranvier - gaps between Schwann
Cells
Synaptic Terminals - neuron ending
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Clusters of Neurons
Ganglion
Cluster of nerve cell bodies in the PNS
Nuclei
Cluster of cells in the brain
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Supporting Cells
Glia (glue)
Astrocytes (structural support)
Creates tight junctions and forms the blood-brain barrier
Radial Glia Form tracks for new neurons formed in the neural tube
Oligodendrocytes
Form myelin sheath in brain
Schwann Cells Form myelin sheath in the PNS
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Reflex
Sensory
neuron
to a
motorneuron
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Neural Signals
Membrane Potential
Sodium-Potassium Pump
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Threshold Potential
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Resting State
Both sodium
and
potassium
activationgates are
closed
Interior of
cell isnegative
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Depolarization State
Sodium
activation
gates are
opened on
somechannels
Interior of
cell
becomesmore
positive
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Rising Phase of Action Potential
Most sodium
activation
gates are
opened Potassium
activation
gates are still
closed
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Undershoot
Both gates tosodiumchannels areclosed
Potassiumchannels areclosing
Membranereturns to itsresting state
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Propagation of
the Action
Potential Localized event
First actionpotentials
depolarization sets
off second action
potential Travels in one
direction due to
refractory period
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Salatory Conduction
Action Potential jumps from node to node
Speeds up signal from 5 m/sec to 150
m/sec
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Communication Between
Synapses
Electrical Synapses
gap junctions allow for direct transfer of action
potential (used during escape responses)
Chemical Synapses
uses neurotransmitters
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Chemical Synapse
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Chemical Synapses
Action potential triggers an influx of calcium Synaptic vesicles fuse with presynaptic
membrane
Neurotransmitter released into synaptic cleft Neurotransmitters bind to receptors and
open ion channels on postsynaptic
membrane which sets off new actionpotential
Neurotransmitters are degraded by enzymes
or removed by a synaptic terminal
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Neurotransmitters
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Postsynaptic Potentials
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Postsynaptic Potentials
Subthreshold doesnt reach threshold
Temporal Summation
two signals do not reach threshold level butoccur close enough to set off action
potential
Spatial Summation
two signals are set off at the same time
setting off an action potential
Spatial Summation with an inhibitor
doesnt reach threshold
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Vertebrate
NervousSystem
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Central Nervous System
Ventricles (4)
Cerebrospinalfluid
White Matter Made up of
axons
Gray Matter
Made up ofdendrites
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Peripheral Nervous System
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Peripheral Nervous System
Autonomic Nervous System regulates the
internal environment (usually involuntary)
Somatic Nervous System regulates the
external environment (usually voluntary)
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Autonomic Nervous System
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Autonomic Nervous System
Sympathetic Division
Flight or fight response
Parasympathetic Division
Rest or digest response
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Brain
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The Brainstem
The Medulla Oblongata and
the Pons controls breathing,
heart rate, digestion
The Cerebellum controls
coordination of movement
and balance
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The Midbrain
The Midbrain receives,
integrates, and projects
sensory information to the
forebrain
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The Diencepholon
Forebrain
Epithalamus
Includes the pineal gland and the
choroid plexus
Thalamus
conducts information to specific areas of
cerebrum
Hypothalamus
produces hormones and regulates bodytemperature, hunger, thirst, sexual
response, circadian rhythms
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The Telencepholon
Cerebrum
with cortex and
corpus callosum
higher thinking
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Cerebrum
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Cerebrum
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Limbic System
Regulates
emotions
Association
with differentsituations is
done mostly
in the
prefrontal
lobe
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Memory
Short Term
Done in the
frontal lobe
Long Term Frontal lobes
interact with
the
hippocampusand the
amygdala to
consolidate
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Sensory Receptors
Mechanoreceptors
Pain Receptors
Thermoreceptors
Chemoreceptors
Electromagnetic Receptors
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Sensory Receptors
Mechanoreceptors
Pain Receptors
Thermoreceptors
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Sensory Receptors
Chemoreceptors
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Sensory Receptors
Electromagnetic receptors
Evolution of the
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Evolution of the
Eye
Complex eyes
have developed
many times
Evolution of the
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Evolution of the
Eye All light-sensitive organsrely on photoreceptorsystems employing a
family of proteins called
opsins. Further, the
genetic toolkit for
positioning eyes is
common to all animals:
the PAX6 genecontrolswhere the eye develops
in organisms ranging
from mice to humans to
fruit flies
http://en.wikipedia.org/wiki/Opsinhttp://en.wikipedia.org/wiki/Pax_geneshttp://en.wikipedia.org/wiki/Drosophila_melanogasterhttp://en.wikipedia.org/wiki/Drosophila_melanogasterhttp://en.wikipedia.org/wiki/Pax_geneshttp://en.wikipedia.org/wiki/Opsin -
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Photoreceptors Eye cups(ocelli) - light
detection Genetic basis
that started as a
light detector
600 mya
During the
Cambrian
explosionaround 540 mya
two types of
eyes arose
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Photoreceptors
Compound Eyes -
made up of
ommatidia that helps
detect movement
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Photoreceptors
Camera Type Eyes
Evolved several
times
Hagfish eye Lamprey eye
Jawed vertebrate
eyes
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Single Lens Eye
Sclera (white)
Cornea (clear)
Choroid (pigmented)
Iris (color of eye)
Retina (rods and cones)
Pupil Fovea (focal point)
Blind spot
S f E l ti
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Photoreceptors Scars of Evolution1. inside out retina
that forces light to
pass through the
cell bodies and
nerves before
hitting the retina2. blood vessels
across the retina
that cause
shadows
3. nerve fibers that
exit causing a blind
spot
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Focusing
Near vision ciliary muscle
contracted
lens becomes
more spherical
Distance vision
ciliary muscle
relaxed
lens becomes
flatter
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Visual Problems
Near-sightedness (myopia)
eyeball too long / focal point in front of fovea
Far-sightedness (hyperopia)
eyeball too short / focal point behind fovea
Astigmatism (blurred vision)
misshapen lens or cornea
H i d E ilib i
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Hearing and Equilibrium
Hearing Organ
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Hearing Organ Outer Ear
pinna and the auditory canal tympanic membrane
Middle Ear
malleus, incus and stapes oval window
Inner Ear
cochlea with the Organ of Corti with a basilar membrane and hair cells
Eustachian Tube
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Sound Volume
amplitude of sound wave
vibrates fluid in ear and bend hair cells whichgenerates more action potentials
Pitch frequency of sound wave
Equilibrium
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Equilibrium
Utricle and Saccule
Semicircular Canals
used to detect body position and movement
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Lateral Line
System Similar to inner ear detects movement of
current, moving
objects
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Statocysts
Equilibrium
contain
statoliths
Sound Systems in
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Sound Systems in
Invertebrates
Body hairs that vibrate
mosquitoes
Tympanic Membranes crickets
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Chemoreception
Taste Buds
sweet (tip), salty
(behind), sour (sides),
bitter (back of tongue)
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Chemoreception
Olfactory receptors cells
upper portion of nasal cavity
The Cost of Locomotion
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e Cost o oco ot o
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The Cost of Locomotion
Locomotion must overcome two forces: gravity
friction
Swimming is more efficient than running runner must overcome gravity
Larger animals travel more efficiently than
smaller animals Flight is the most costly (per minute)
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Skeletal Structures
Hydrostatic Skeleton
(cnidaria, ctenophora, platyhelminthes,
nematoda, annelida)
Exoskeletons mollusca, arthropoda
Endoskeletons
chordata
Cooperation of Muscles and
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Cooperation of Muscles and
Skeletons Muscles always
contract
Muscles
attached inantagonistic
pairs
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Skeletal Muscles
Muscles are made up ofmuscle fibers
Fibers are made up of
myofibrils Myofibrils are made up of
myofilaments
thin filaments (actin)
thick filaments (myosin)
Sliding Filament
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Sliding Filament
Model
Sacromeres (basic
functioning unit)
Z lines (border of
sacromeres)
H zone (center of
sacromere)
I band (only thin filaments)
A band (length of thick
filaments)
Sliding Filament
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Sliding Filament
Model During contraction, thin
and thick filaments slide
past each other
I band and H zonedecreases in size
Caused by myosin
head creating cross
bridge with actin fiberand then moves by
using ATP
Muscle
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Muscle
Control
Tropomyosinblocksmyosinbinding sites
Calcium ionsallow crossbridges toform
M l Fib
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Muscle Fibers
Fast Muscle Fibers
rapid, powerful
contractions
flight muscle
Slow Muscle Fibers
sustain, long
contractions
adductor muscles
I t b t M l
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Invertebrate Muscles
Flight muscles in insects are capable ofindependent contractions
wings beat faster than action potentials
Clam muscles contain paramyosin thatallows them to remain contracted with little
energy
Nematodes only have longitudinal musclethat gives them their characteristic
movements
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