nervous system
DESCRIPTION
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
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:• 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
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
So, you mean to tell me… they don’t THINK??!!??!!
Ohhhh, but this net brings purposeful movements
Evolution of:• More complex animals actually have multiple
nerve cells bound together
• Information flows along a specific route
Nerve net
Eyespot
Brain
Nervecords
Transversenerve
Brain
Ventralnerve cord
Segmentalganglia
(c) Planarian (flatworm) (d) Leech (annelid)
Simplest CNS
Evolution of:• Elongated, bilaterally symmetrical organism are
CEPHALIZED
• Clustering of neurons at at the front end of the body…
ex. Cephalization: ANNELID
ex. Cephalization: ARTHROPOD
ex. Cephalization: VERTEBRATE
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
Organization of Vertebrate Nervous System
The spinal cord conveys information from and to the brain