Animal Nervous Systems

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• Animal Nervous Systems
• I. Selective Forces
• -- animals must detect and respond to
  stimuli (environmental
• and internal)
• detect stimuli and convert into nervous impulses
  (sensory systems)
• process information and make decisions (central
  nervous system)
• perform an appropriate response (motor systems
  behavior)

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• Animal Nervous Systems
• II. Irritability
• -- fundamental property of life
• -- ability to respond to environmental stimuli
• -- inherent property of cell membranes ions
  flow across membrane
• through special channels, generating
  electrical events
• -- found in protozoa
• -- Cnidaria Chordata have neurons

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• Animal Nervous Systems
• III. The Neuron
• A. Structure
• 1. neuron components

axon
(Fig. 33-2 p. 709)
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• Animal Nervous Systems
• III. The Neuron
• A. Structure
• 2. glial cells

neuron
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Animal Nervous Systems III. The Neuron
B. Functional types of neurons 1. sensory
(afferent) 2. motor (efferent) 3.
interneuron 4. reflex arc
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Reflex Arc (Fig. 33-11 p. 717)
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• Animal Nervous Systems
• III. The Neuron
• C. Neuronal membrane semipermeable
• 1. Na channels K channels
• -- chemically gated channels
  electrically gated channels

Outside neuron
Inside neuron
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• Animal Nervous Systems
• III. The Neuron
• C. Neuronal membrane
• Sodium-potassium pump

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Animal Nervous Systems III. The Neuron
C. Neuronal membrane 2. neuron at rest
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Internal charge -- Na channels
closed Naout gtgt Nain Na drawn into cell
by diffusion gradient electrical gradient
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• Internal charge
• Naout gtgt Nain
• K channels open
• Kin gtgt Kout

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Animal Nervous Systems III. The Neuron
C. Neuronal membrane 2. neuron at rest
-- resting potential -60 to -70 mV
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Animal Nervous Systems III. The Neuron
C. Neuronal membrane 3. action potential
self propagating depolarization of neuronal
membrane
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Action Potential
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Animal Nervous Systems III. The Neuron
D. Speed of conduction 1. axon
diameter -- as diameter increases, speed of
conduction increases -- giant axons
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Animal Nervous Systems III. The Neuron
D. Speed of conduction 2. sheathing in
vertebrates and insects in
vertebrates -- myelin sheath --
produced by Schwann cells (peripheral NS)
by oligodendrocytes (CNS type of glial
cell) -- Nodes of Ranvier
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Figure 33.06
Saltatory conduction
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Animal Nervous Systems III. The Neuron
E. Communication between neurons chemical
synapse 1. structure
presynaptic neuron
postsynaptic neuron
AP
vesicles of neurotransmitter
synaptic cleft
(Fig. 33-7 p. 713)
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Animal Nervous Systems III. The Neuron
E. Communication between neurons chemical
synapse 2. function
(Fig. 33-8 p. 714)
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Animal Nervous Systems III. The Neuron
E. Communication between neurons chemical
synapse 3. functional types of chemical
synapses a. Excitatory cause
postsynaptic membrane to depolarize b.
Inhibitory cause postsynaptic membrane to
hyperpolarize, or prevents
depolarization
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Animal Nervous Systems III. The Neuron
E. Communication between neurons chemical
synapse 4. summation of synaptic inputs
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• Animal Nervous Systems
• III. The Neuron
• E. Communication between neurons
  chemical synapse
• 5. types of neurotransmitters
• Acetylcholine (Ach) broken down by
  acetylcholinesterase
• norepinephrin
• dopamine serotonin
• GABA always inhibitory

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Animal Nervous Systems III. The Neuron
E. Communication between neurons chemical
synapse 6. neuromuscular junction --
releases Ach -- causes sarcolemma to
depolarize sarcoplasmic reticulum
releases Ca
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Animal Nervous Systems IV. Types of Nervous
Systems A. Nerve net (plexus) -- found in
all animals -- nervous system of Cnidaria
-- no brain, no CNS -- adapted for radial
symmetry
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems --
composed of central nervous system (CNS brain
and main nerve cords) and peripheral nervous
system (sensory and motor neurons) --
associated with cephalization
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates -- main brain (often grows
around gut) -- paired, solid ventral nerve
cords
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 1. Phylum Platyhelminthes
(Fig. 33-9 p. 715)
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 2. Phylum Annelida
supraesophageal ganglion (excitatory)
circumesophageal connectives
subesophageal ganglion (inhibitory)
paired ventral nerve cords
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 3. Phylum Arthropoda
segmental ganglia
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 3. Phylum Arthropoda
a. Brain (supraesophagael ganglion)
Protocerebrum vision higher order behaviors
Deuterocerebrum olfaction
Tritocerebrum
Circumesophagael connectives
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 3. Phylum Arthropoda
b. Subesophagael ganglion c. Ventral
nerve cords
subesophagael ganglion
ventral nerve cords
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 3. Phylum Arthropoda
d. segmental ganglia
thoracic ganglia
caudal ganglion
abdominal ganglia
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
invertebrates 3. Phylum Arthropoda
e. Hierarchical arrangement of arthropod
CNS -- brain (protocerebrum) is major
inhibitory center -- subesophagael ganglion
is major excitatory center -- protocerebrum
inhibits behavioral programs until receiving
correct stimulation -- disinhibits
specific regions of subesophagael ganglion
send excitatory messages to thoracic and
abdominal ganglia activating specific
behavior programs ex mating in praying
mantis
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates -- main brain -- single hollow,
dorsal nerve cord (spinal cord)
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 1. spinal cord
meninges
Gray matter
dorsal root
Dorsal root
Ventral root
White matter
ventral root
spinal nerve
central canal
cerebrospinal fluid
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain
Ancestral vertebrate plan
Midbrain (vision higher order behavior)
Hindbrain (hearing balance)
Forebrain (olfaction)
Spinal cord
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Midbrain (vision higher order behavior)
Hindbrain (hearing balance)
Forebrain (olfaction)
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain a. Hindbrain
1) mylencephalon -- medulla
oblongata subconscious vital activities
heartbeat, breathing, swallowing part
of brain stem
Hindbrain
mylencephalon
medulla oblongata
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain a. Hindbrain
2) metencephalon -- cerebellum
equilibrium, posture, precision control center
for movement -- pons
Hindbrain
mylencephalon
metencephalon
cerebellum
pons
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Figure 33-14 p. 720
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain b. Midbrain
mesencephalon -- optic lobes
visual center higher behavior in fish
amphibians -- corpora
quadragemina in mammals visual reflex
communication with other regions
Hindbrain
Midbrain
mylencephalon
metencephalon
mesencephalon
optic lobe
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Figure 33-14 p. 720
Corpora quadragemina
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain c. Forebrain
1) diencephalon -- thalamus
major relay/processing center part of limbic
system
Hindbrain
Midbrain
Forebrain
mylencephalon
metencephalon
mesencephalon
diencephalon
thalamus
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain c. Forebrain
1) diencephalon -- hypothalamus
pituitary gland (1) basic drives (2)
homeostasis (3) neurosecretory center
(neurohormones neuropeptides)
Hindbrain
Midbrain
Forebrain
mylencephalon
metencephalon
mesencephalon
diencephalon
hypothalamus
pituitary gland
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain c. Forebrain
1) diencephalon -- pineal
gland associated with biological rhythms
Hindbrain
Midbrain
Forebrain
mylencephalon
metencephalon
mesencephalon
diencephalon
pineal gland
hypothalamus
pituitary gland
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Figure 33-14 p. 720
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain c. Forebrain
2) telencephalon -- olfactory
lobes paleocortex part of limbic system
-- cerebrum neocortex higher behavior in birds
mammals conscious mind
Hindbrain
Midbrain
Forebrain
mylencephalon
metencephalon
mesencephalon
diencephalon
telencephalon
cerebrum
olfactory lobe
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 2. brain c. Forebrain
-- cerebrum sensory areas
vision, hearing, motor control for voluntary
muscles left hemisphere language, math,
learning, sequential thought right hemisphere
spatial, musical, artistic intuitive
abilities corpus callosum connects two
hemispheres fornix connects cerebrum to
thalamus
fornix
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Figure 33.13
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 3. Peripheral nervous system
a. Somatic nervous system -- innervates
skeletal muscles -- voluntary
nervous system -- locomotion
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 3. Peripheral nervous system
b. Autonomic nervous system -- involuntary
nervous system 1) parasympathetic
system -- release Ach (cholinergic
neurons) -- associated with non-stressful
activities (eating digestion) -- inhibits
heartbeat -- excites gut salivary
glands -- constricts iris
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Animal Nervous Systems IV. Types of Nervous
Systems B. Bilateral Nervous Systems
vertebrates 3. Peripheral nervous system
b. Autonomic nervous system -- involuntary
nervous system 1) parasympathetic
system -- release Ach --
associated with non-stressful activities (eating
digestion) -- inhibits heartbeat --
excites gut salivary glands -- constrict
iris 2) sympathetic system
-- release norepinephrin -- associated with
stress -- excite heartbeat -- inhibit
gut salivary glands -- dilate iris