Transcript The Nervous System

The Nervous System
By: Amor Colombres & Cellena Ward
Cnidaria: Hydra
•
Hydras have a nerve net that connects receptors with
muscle and gland tissues, but they do NOT have a brain
or any nerve cords to connect their nervous system.
A Hydras Nervous System
•
•
•
The neurons of a
hydra are connected
by the synapse and
can be in either
direction of the
synapse.
Unlike other animals
the hydra does NOT
have any grouping of
cell bodies.
The hydra also does
NOT have any cells
that are specialized
for touch or chemical
detection.
Annelida: EarthWorm
•
•
An earthworm has both a central and peripheral nervous system
In the central nervous system the cerebral ganglion is connected to the
ventral nerve cord and runs the entire length of the body. Each
segmental ganglion branches off of the ventral nerve cord, therefore
connecting all of the segments to the brain.
Peripheral Nervous System
•
The peripheral nervous
system contains neurons
that branch off of the
central nervous system
and each neuron transmit
messages to the cerebral
ganglion:
 Sensory
neurons carry
impulses from
receptors to the
nerve cords.

Motor neurons
carry impulses
from the nerve
cord to effectors.
The Adaptations of Earthworms
•
•
The nervous system is very
critical to the earthworms
because it helps to coordinate
with the nerve responses
and allows the earthworm to
survive.
Over time the Earthworms
have adapted receptors that
make them sensitive to:
 Light
 Pressure
 Vibrations
 Heat
 Chemicals
Arthropoda:Grasshopper
•
•
•
Grasshoppers also have a central
and peripheral nervous system.
The peripheral nervous system
consists of the sensory system.
while the central nervous system
consists of the ventral nerve cord.
Since the grasshopper is a
segmented insect each segment
has its own interganglionic.
The Advantages of Grasshoppers
•
•
Grasshoppers have:
 Antennae
 Eyes
 Taste and Sound Organs
Grasshoppers also have four
important neurons that connect to the
extensor muscle.
 fast extensor tibiae
 slow extensor tibiae
 common inhibitor
 dorsal unpaired median
neuron of the extensor
tibiae
Parkinson's Disease
•
•
•
Parkinson's disease is considered a motor system
disease because it affects the motor skills first.
Causes:
 Old Age
 Genetics
 When the nerve cells in the brain that make
dopamine are slowly destroyed.
 Nerves that are not sensitive to dopamine
cause Parkinson in young children
Symptoms:
 Tremor
 Difficulty swallowing
 Loss of automatic movements
 Rigid Muscles
 Change in Speech
 Impaired Posture or Balance
The Cures of Parkinson's
•
Cures:

Levodopa (L-dopa), Sinemet, levodopa and carbidopa (Atamet)
 Pramipexole (Mirapex), ropinirole (Requip), bromocriptine (Parlodel)
 Selegiline (Eldepryl, Deprenyl), rasagiline (Azilect)
 Amantadine or anticholinergic medications -- to reduce early or mild
tremors
 Entacapone -- to prevent the breakdown of levodopa
 Changes in lifestyle
•
•
Epilepsy
Is a disease of the nervous system that affects the temporal lobe
and causes repeated convulsions that eventually changes a
person's attention or behavior.
Causes:
 Damage to the brain tissue.
 Dementia
 Traumatic brain injury
 Infections of the nervous system
 Brain problems at birth
 Brain tumor
 Abnormal blood vessels in the brain
•
•
Continuation of Epilepsy
Symptoms:
 Partial seizure
 Absence seizure
Treatment:
 Vitamins and supplements
 Lifestyle changes
 Surgery to remove abnormal
brain cells
 Anticonvulsants
 Surgery to insert vagus
nerve stimulator
Embryonic Development of Vertebrates
• The central nervous system
•
develops from the hollow, dorsal
nerve chord. The central canal
and ventricles form in the cavity
of the nerve chord.
These cavities are filled with
cerebrospinal fluid.
Grey and White Matter
• Grey matter consists of
•
•
neuron cell bodies, dendrites,
and unmyelinated axons.
White matter consists of
bundled axons with myelin
sheaths.
In the spinal chord, the white
matter surrounds the grey
matter, so the function goes
with the anatomy, linking the
CNS with sensory and motor
neurons of the PNS
Glia Cells
• Non-neural
cells that form myelin, help maintain homeostasis, and
provide support and protection for neurons in the cell.
o
o
o
o
o
•
•
Ependymal cells
Astrocytes
Oligodendrocytes
Schwann cells
Microglia
In embryonic development, radial glia form a track for new neurons
migrate from the neural tube, astrocytes later form junctions along
these lines.
In the blood-brain barrier these cells control the extracellular
environment by restricting the entry of substances from the blood
into the brain.
Autonomic Nervous System
• Part
of the peripheral nervous system that
regulates smooth and cardiac muscle.
• Three
parts:
o Sympathetic division controls arousal
and energy generation
 i.e. heart beating faster
o Parasympathetic division controls
calming and self-maintenance
functions
 i.e. heart rate decreasing
o Enteric division regulates secretion
and peristalsis.
 occurs in digestive tract,
pancreas, and gall blader
The Vertebrate Brain is Regionally Specialized
• Three regions:
•
•
•
o
Forebrain
o
Midbrain
o
Hindbrain
The forebrain develops into two regions,
the diencephalon and telencephalon.
The midbrain develops into the
mesencephalon.
The hindbrain develops into the
metencephalon and myelencephalon.
The Cerebrum
• Controls skeletal muscle contraction, center for learning,
emotion, memory, and perception
• The cerebral cortex is vital for perception, voluntary
movement, and learning.
• The corpus callosum is a structure that enables the
right and left hemispheres to communicate.
• Deep in the white matter there are basal nuclei, which
•
are centers for planning and learning movement
sequences.
Damage during embryonic development can cause
Cerebral Palsy.
The Diencephalon
•
Becomes the thalamus,
hypothalamus, and
epithalamus in children
and adults.
o Thalamus- main input
center for sensory
information.
o Hypothalamus- the body's
biological clock and
thermostat. Partakes in
regulation of systems.
o Epithalamus- in charge of
the pineal gland, which
produces serotonin.
The Cerebellum
Major function is to
coordinate movement and
balance.
Receives sensory
information about the
positions of joints and the
lengths of muscles.
Contains the center for
the auditory and visual
systems.
Has a lot to do with
hand-eye coordination.
•
•
•
•
The
Brainstem
Receives
and
integrates sensory
information to regions
of the brain
• The Pons and
medulla oblongata
transfer information
between the PNS and
the midbrain or
forebrain.
Arousal and Sleep
• Regulated
by the brainstem and
cerebrum.
• Arousal
is a state of awareness of
external stimuli.
• Sleep
is a state where external
stimuli are received but not
perceived consciously.
o
active state when the brain
condenses memories and learning.
• Controlled
mainly by the reticular
formation, network of neurons in
the core of the brainstem that acts
like a sensory filter.
Biological Clock Regulation
•
•
•
Cycles of sleep and
arousal are examples of a
circadian rhythm.
molecular mechanism that
regulates gene expression
and cellular activity
The hypothalamus
contains a group of
neurons, suprachiasmatic
nucleus (SCN), that
coordinate circadian
rhythms.
Emotions
•
Many structures control emotions like the
amygdala, hippocampus, and thalamus, or the
limbic system.
Feeling emotion requires other structures in the
brain, like the brainstem and cerebrum.
The amygdala stores emotions as memories.
•
Language and Speech
•
•
•
Physician, Pierre Broca,
discovered Broca's Area
which controls muscles of
the face.
Karl Wernicke found that
when damaged, Wernicke's
area, suppressed the ability
to comprehend speech, but
not to actually speak.
Two regions work together in
reading, generating words,
speaking words, and hearing
words.
Lateralization of Cortical Function
• Left hemisphere functions:
•
o
math and logical operations
Right hemisphere functions:
o
recognition of faces and patterns, spatial
relations, and nonverbal thinking.
• Hemispheres trade
information through the
corpus callosum.
Frontal Lobe Function
•
•
Phineas Gage had a 3
cm rod enter his skull just
under his left eye and
exited through the top of
his head. The rod
destroyed a very large
portion of his frontal lobe.
He was able to recover,
but his emotions
changed.
This left a connection
with the frontal lobe and
emotional responses.
Changes in Synaptic Connections
•
•
Neurons need to compete
for growth-supporting
factors, which direct
neuron growth.
Synapse elimination occurs
because neurons form
extra synapses then
needed for its function,
about half of original
synapses are destroyed by
the end of embryonic
development.
Neural Plasticity
•
•
•
•
The ability of the
nervous system to be
remodeled.
Reshaping occurs at
synapses.
The connections are
strengthened or
weakened depending
on activity between
neurons.
Autism is due to a
disruption remodeling
of synapses.
Memory and Learning
• Keep memories in our
•
•
short-term memory until
it becomes irrelevant.
When memories are
remembered they are
stored in our long-term
memory.
Both memories store
information in the cerebral
cortex.
Long-Term Potentiation (LTP)
• The increase of the strength
•
•
of the flow of
communication across
synapses.
For this to occur there
needs to be a highfrequency series of action
with a presynaptic neuron.
Glutamate receptors in the
postsynaptic membrane
change in response to
depolarization, allowing LTP
by inserting glutamate
receptors.
Stem Cells in the Brain
• Develop into neurons
•
that mature and
migrate to the
hippocampus to be
included into the
nervous system.
Researchers are
trying to use neural
stem cells to replace
lost brain tissue.
Bibliography
"The Grasshopper Nervous System." Motor System. Web. 25 Mar. 2012.
<http://www.st-andrews.ac.uk/~wjh/jumping/motorsys.htm>.
"Neuroscience for Kids - Invertebrate Nervous System." UW Faculty Web Server. Web.
25 Mar. 2012. <http://faculty.washington.edu/chudler/invert.html>.
Staff, Mayo Clinic. "Definition." Mayo Clinic. Mayo Foundation for Medical
Education and Research, 15 Feb. 2011. Web. 25 Mar. 2012.
<http://www.mayoclinic.com/health/parkinsonsdisease/DS00295/DSECTION=symptoms>.
"Epilepsy Symptoms: Partial Seizures, Generalized Seizures, and More." WebMD.
WebMD, 03 May 0005. Web. 25 Mar. 2012.
<http://www.webmd.com/epilepsy/tc/epilepsy-symptoms>.
Board, A.D.A.M. Editorial. "Causes, Incidence, and Risk Factors." Epilepsy. U.S.
National Library of Medicine, 18 Nov. 0000. Web. 25 Mar. 2012.
<http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001714/>.
Reece, Urry, Cain, Wasserman, Minorsky, and Jackson. San Francisco: Pearson
Education, 2011. Print.