lecture notes according to powerpoint slides

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Published on 2 Mar 2011
School
UTSC
Department
Biological Sciences
Course
BIOA02H3
Professor
LECTURE 10 (Chapter 44)-Nervous Systems
Overview: command and control center
What cells are unique to the nervous system?
oIn the nervous system, the nerve cells/neurons are unique and are unique to
the animal kingdom and so we see their function only in multicellular
animals
oall animals have nerve cells except for sponges
osponges are that first multicellular group that are barely animal-like
othe upshot into how we can distinguish one group from the next and watch
the evolutionary sequences different animals developed more elaborated
nervous systems is looking at how they’re organized and how the information
may get processed and how much information may be able to be processed
oneurons carry out 3 jobs:
receive information from sensory or cells that are picking up
information from the environment or other parts of the body
they encode that information and allow for interpretation and
integration of that information
they transmit the information in a form that performs the appropriate
response for the stimulus that has been picked up from the
environment
Organization of Neurons
oNerve net: network of neurons all around the body that allow this animal to
respond equally in all directions
oRadially symmetrical organisms are not bilateral therefore they dont have
sephalization the formation of a head concentration of nerve tissue. They act
equally in all directions.
oConcentration of neurons in the head region(brain) for bilateral organisms
(worms)
Ganglia: concentration of nerve cells but not as big as the brain
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You have ganglia in each segment and nerves branching off from that
ganglia that support and react to responses within that individual
segment
This series of ganglia are connected by a nerve cord and that is on the
ventral side of the organism so its on its underside
Kidney system in each segment
Segemented organisms have all of their physiological structures in
each of the segments so they act somewhat independently but
coordination is still involved and hence the role of the brain or the
center ganglia and head region
oOctopus/squids: invertebrates so we like to think that they’re less advanced
They have a lot of nerves going to the muscles of the legs and other
parts of the body
Nerves involved in the gut system (eating/opening and closing
mouth/digestion/relaxing etc)
Significant concentration of nervous tissue in the head region so a
brain
Significant nervous tissue/ganglia associated with their visual senses
They see in an experiment that octopus reacts to HD tv...they get
happy when they see their mate and get scared when they see an
angry male. However they did not see this on regular tv. This shows
that they have a very sensitive visual system.
Variation in Brain Size in Vertebrates
oAll of the brains have a brain stem and the cerebellum
oMedulla
oIts not about brain size, its about how the neurons are interconnected
oThe central nervous system is taking information from the outside world
thats brought to it by the nerve tissues around the body, integrates that
information, determines an appropriate response and sends the message
through the peripheral system to the appropriate structures to the response
required
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