The Nervous System
Define the following terms:
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Nerve system
Receptor
Stimulus
Neuron
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Impluses
Effector
Brain
Synapse
In paragraph/diagram form, explain how all these terms
are related to one another.
Draw a neuron and label the following
parts:
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Cell body
Nucelus
Axon
Schwann Cell
Synaptic Knobs
To Do:
• Explain the difference between nerves,
sensory neurons, motor neurons, and
interneurons.
Protists
• Lack nervous system
• Respond to stimuli in a coordinated way
• Not totally understood, but
are able to tell diff. b/n
light/harmful chemicals,
food/nonfood.
• Amoeba Feeds!
http://www.youtube.com/
watch?v=W6rnhiMxtKU
Hydra
• Has a nerve net
• Nerve cells form irregular network
b/n 2 layers of body wall
• Impulses cause muscles to respond
– E.g. Tentacle touches food 
impulse travels through organism
 animal stretches towards food
 tentacles capture food and stuff
into mouth
• http://www.youtube.com/watch?v
=Zgp7cutpO8o&feature=related
Earthworm
• More complex nervous
system
• Divided into the central
and peripheral system
– Central: brain + ventral
nerve cords
– Peripheral: nerves
branching to all parts of
body
• Has motor neurons (carry
impulses from nerve cords
to muscles) and sensory
neurons (impulses from
receptors in skin to nerve
cords)
Grasshopper
• Similar to the
earthworm
• Made of brain, ventral
nerve cord, ganglia
(group of cells that coordinate impulses)
• Sense organs are better
developed
– Has eyes (antennae) or
feelers, taste organs, and
are sensitive to sound
To Do:
• Summarize in your notes how the nervous
system increases in complexity from the
protists to the grasshopper. (Can draw a
diagram if it is helpful to you)
Human Nervous System
• Made up of the central
and peripheral system
– Central: made of
brain, spinal cord,
interneurons, and
motorneurons.
Controls most
activities of the body
– Peripheral: network of
nerves, conduct
impulses b/n central
nervous system &
receptors/effectors of
the body
To Do:
1) Draw a concept map of the brain explaining the
3 main parts and the functions they control
2) Outline the 2 main functions of the spinal cord.
http://www.youtube.com/watch?v=udaCEBtqfb
(~ 4 to 10 minutes)
3) Explain what a reflex is and the process that
happens when you touch something hot and
your hand withdraws.