nervous system
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Nervous system. Fun facts about neurons. Most specialized cell in animals Longest cell blue whale neuron 10-30 meters giraffe axon 5 meters human neuron 1-2 meters. Nervous system allows for 1 millisecond response time. Evolution of:. - PowerPoint PPT PresentationTRANSCRIPT
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Nervous system
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Fun facts about neurons• Most specialized cell in
animals• Longest cell– blue whale neuron• 10-30 meters
– giraffe axon• 5 meters
– human neuron• 1-2 meters
Nervous system allows for 1 millisecond response time
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Evolution of:• The simplest animals with nervous systems, the
cnidarians, have neurons arranged in nerve nets~
• A nerve net is a series of interconnected nerve cells, these are not specialized at all
Nerve net
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Evolution of:• All these do is contract and relax the
gastrovascular cavity… THAT’S IT!!!~
• A nerve net is a series of interconnected nerve cells, these are not specialized at all
Nerve net
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So, you mean to tell me… they don’t THINK??!!??!!
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Ohhhh, but this net brings purposeful movements
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Evolution of:• More complex animals actually have multiple
nerve cells bound together
• Information flows along a specific route
Nerve net
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Eyespot
Brain
Nervecords
Transversenerve
Brain
Ventralnerve cord
Segmentalganglia
(c) Planarian (flatworm) (d) Leech (annelid)
Simplest CNS
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Evolution of:• Elongated, bilaterally symmetrical organism are
CEPHALIZED
• Clustering of neurons at at the front end of the body…
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ex. Cephalization: ANNELID
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ex. Cephalization: ARTHROPOD
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ex. Cephalization: VERTEBRATE
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Evolution of:• In vertebrates
– The CNS is composed of the brain and spinal cord– The peripheral nervous system (PNS) is composed of
nerves and
ganglia.Nerve net
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Organization of Vertebrate Nervous System
The spinal cord conveys information from and to the brain