Download Zoology 242 Anatomy of Nervous systems Lecture 8

Zoology 242
Anatomy of Nervous systems
Lecture 8
Moyes and Schulte 308-332
Zoology 242 - Lecture 8
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Basic plan of nervous system
Fig 7.1
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Some terms
• Afferent – originates from distal point and
projects towards the region in question, e.g.
sensory afferent neuron.
• Efferent – originates from the region in question
and projects towards a distal point. e.g. motor
efferent neuron.
• Interneuron – integrating neuron which remains
within the central nervous system
• Effector – tissue (muscle, gland, etc). which
produces the effect.
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Organization of Nervous systems
Nervous systems generally follow the
same organization and plan of their
body arrangement. (Fig 7.4)
Radially symmetrical
Zoology 242 - Lecture 8
Bilaterally symmetrical
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Organization of Nervous systems
(Part 2)
•
The evolutionary
emergence of an
anterior ganglion
(collection of cell
bodies) was the
start of the
process of
cephalization and
eventual
formation of
brains.
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The meninges of vertebrates
• a well developed
multilayered sheath
around the central
nervous system –
protection
– Dura Mater – thick, tough
– Arachnoid – weblike
– Pia mater – thin inner
layer.
• Holds cerebrospinal
fluid as a protective
liquid bath around our
CNS.
Fig 7.6
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Segmentation
•
•
•
•
•
•
Cranial
Cervical
Thoracic
Lumbar
Sacral
Coccygeal
Fig 7.5 A
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Developing nervous system
• Starts off as a closed tube with the closed
off portion anterior.
• As development proceeds, the tube
develops vesicles (swellings)
• These swellings become major anteriorposterior subdivisions (Primary vesicles)
• These subdivisions then form additional
swellings and sub-subdivisions
(Secondary vesicles)
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Developing Vertebrate Nervous
System
• 3 major subdivisions – 3 vesicle stage
–
–
–
–
Prosencephalon
Mesencephalon
Rhombencephalon
Spinal Cord
• 5 vesicle stage
–
–
–
–
–
–
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
Spinal Cord
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3 Brain Vesicle stages
(see next page)
• Forebrain (Prosencephalon)
– Telencephalon - Olfactory Bulb, cerebral cortex,
hippocampus, amygdala)
– Diencephalon - thalamus, hypothalamus, epithalamus
• Midbrain (Mesencephalon)
• Hindbrain (Rhombencephalon)
– Metencephalon (Pons, cerebellum)
– Myelencephalon (medulla)
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Sagittal view of generic mammalian
brain. (Fig 7.7)
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So how different are our brains
from other animals?
From
Campbell
8th Edition
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Brains are relatively
conserved across
vertebrate groups.
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Brain sizes scale to animal size
Northcutt, R. G. Integr. Comp. Biol. 2002 42:743-756; doi:10.1093/icb/42.4.743
Copyright
restrictions
apply. 8
Zoology
242 may
- Lecture
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Who’s got fancier cortexes?
Hagfish
Human
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5 layered cortex in hagfish
From Wicht H and Northcutt RG (1998)
J Comp Neurol. 395(2):245-60.
Zoology 242 - Lecture 8
6 layered cortex in humans
From Jones EG (2000) 97(10):5019-21.
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Function of brain regions
(based on table 7.2)
Telencephalon
Zoology 242 - Lecture 8
Cerebrum
(cortex in
mamals)
Basal Ganglia
Information
processing
Amygdala
Emotions
Hippocampus
Memory
Olfactory Bulb
Sense of smell
Accessory
Olfactory
system
Detection of
pheromones.
Movements
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Function of brain regions
(based on table 7.2)
Diencephalon Thalamus
Zoology 242 - Lecture 8
Sensory Relay to
telencephalon
Hypothalamus, Regulate body
pituitary
temp, feeding,
reproduction,
circadian rhythms,
ENDOCRINE
Epithalamus
Melatonin
(Pineal)
secretion,
regulation of
hunger/thirst.
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Mesencephalon
Optic tectum (also
called superior
colliclus)
Processes spatial visual
(and some auditory and
mechanosensory)
information
Auditory processing
Torus
semicicularis
(Inferior colliculus)
Hindbrain
Zoology 242 - Lecture 8
Tegmentum
Mediates reflex responses
to visual/aud stimuli
Pons
Regulates breath-holds
Integrative
Cerebellum
Body posture
Coordinates locomotion
“Attention”
Medulla
Oblongata
Generates rhythmic
breathing
Regulates HR and BP
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Peripheral Nervous System
• Autonomic Nervous system
– Parasympathetic
– Sympathetic
– Enteric
• Cranial Nerves
• Dorsal Root Ganglia
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Autonomic Nervous System
• 3 major divisions described by John Langley (18521925).
– Enteric
– Parasympathetic
– Sympathetic
• Has a synapse between neurons that is peripherally
located (i.e. outside the CNS).
• Synapses occur in autonomic ganglia.
• The sympathetic ganglia segmentally arranged are
called paravertebral ganglia (next to the vertebrae),
also called sympathetic chain ganglia.
• Parasympathetic ganglia are located close to or within
the organ being controlled.
• Sympathetic and parasympathetic are generally
antagonistic of each other.
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Autonomic nervous system
organization
• For the CNS to communicate with the vital
organs (heart, gut, lungs), it takes a chain
of 2 cells to send a signal.
• Cell 1 = preganglionic neuron
– Located within the CNS and sends axons to
an autonomic ganglion.
• Cell 2 = postganglionic neuron.
– located within the autonomic ganglion then
sends axons to the tissue.
Zoology 242 - Lecture 8
Based on Hill 10.12
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Sympathetic vs Parasympathetic
regulation
Fig 7.17
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Parasympathetic
projections
originate from the
cranial nerves and
sacral portion of the
spinal cord.
X
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Sympathetic
projections
originate from the
thoracic and lumbar
portions of the
spinal cord.
X
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Neurotransmitters of pre/post
ganglionic neurons of the autonomic
nervous system
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Classic Cranial Nerves
• Nerves that originate from within the brain
(as opposed to the spinal cord) and exit
through the skull.
• Serves both sensory and motor functions
depending on nerve.
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Classic Cranial Nerves
#
I
II
III
IV
V
Name
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
VI Abducens
Zoology 242 - Lecture 8
S
S
M
M
S
M
M
Function
Olfactory epithelium
Retina
Int/Ext eye muscles
Ext eye Muscles
Jaw muscles, touch to face,
snout and oral cavity
Ext Eye muscles
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# Name
VII Facial
Function
S Taste buds, facial muscles,
M salivary & tear glands
S Cochlea, vestibular organs
VIII Vestibulo/
auditory
IX Glossophar- S Taste buds, pharynx, salivary
M gland
yngeal
S Taste buds, viscera of
X Vagus
M thorax/abd, larynx, pharynx
XI Spinal
Neck Shoulder Muscles
Accessory M
XII Hypoglossal M Tongue
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How to learn cranial nerves
• “On Old Olympus Towering Tops, A Finn And
German Viewed Some Hops”
– For remembering the order of cranial nerves
OR
“Oh, oh, oh, to touch …” (Google this if you really need
to know)
• "Some Say Marry Money, But My Brother Says
Big B___ Matter More“
– For remembering which cranial nerves are Sensory,
Motor, or Both.
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Some additional cranial nerves
T
Name
Aff
Innervation
Terminalis
I?
Nasal septum
(most vertebrates)
VN Vomeronasal I ?
Vomeronasal organ
(amphib, reptile, mammal)
E
Epiphyseal
II ?
Pineal gland
(all vertebrates)
LL
Lateral line
VIII ? Lateral line organs
(all aquatic animals)
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Learning Objectives
•
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•
•
•
•
•
•
Define the following terms: afferent, efferent, interneuron, effector.
Describe the difference between the nervous system of a starfish and a
flatworm.
What are the layers and their functions in the meninges of humans?
What are the major anterior-posterior divisions of the spinal cord?
Name the divisions of the nervous system in development at the 3 vesicle
stage and the 5 vesicles stage. What are the common anatomical names of
the structures that these divisions give rise to and what are their generaly
functions?
What are the major divisions of the autonomic nervous systems and what
are their effects on different effectors?
Define preganglionic and post ganglionic neuron.
Compare and contrast the organization of the preganglionic and
postganglionic neurons in the parasympathetic and sympathetic nervous
systems.
What are the 12 classic cranial nerves and their functions?
What are the functions of some of the “additional” cranial nerves?
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