Transcript cell_communication_for_teachers

CELL COMMUNICATION
Activity developed during the 2009 Exploratorium Summer Institute “Class Menagerie” by:
Caltech Fellow Xoana Troncoso
and High School Teachers Patricia Dunlap, Robert Martin & Erick Roldan
Background
While driving in our cars, if we would like to know how fast we are going, we have the luxury of
simply looking at the speedometer. There are clocks and calendars for time, thermometers for
temperature, and scales to tell us exactly how much mass an object has. We live in a world of
absolutes!
However at the cellular level things are not so convenient. Our cells don’t have the luxury of
using tools as measuring devices, but they do have one very powerful resource: each other! All
of our cells are in constant communication with each other; imagine a party where everyone is
talking to everyone at the same time. Specialized cells in our brains called neurons communicate
by firing electrical signals called action potentials. People have even discovered ways to listen in
on these electrical conversations.
What scientists have discovered is that these specialized cells are only able to interpret data by
constantly comparing values to each other. For example, the only way that your brain can tell
that a piece of paper is white, is by having white sensing neurons and dark sensing neurons
have an electrical conversation in which they compare their values.
UP - DOWN
Play the FALLS_loop.mov movie
What’s going on???
No movement
Rested neurons
Downward movement
No movement
Rested neurons
Tired DOWN neurons
No movement
Rested neurons
DOWN neurons
UP neurons
Compare UP &DOWN
=
>
<
=
NO
movement
DOWN
movement
UP
movement!!
NO
movement
We see…
Expansion - Contraction
No movement
Rested neurons
Contraction
Rested neurons
CONTRACT neurons
No movement
Tired CONTRACT
neurons
No movement
Rested neurons
<
=
EXPAND neurons
Compare CONTRACT & EXPAND
=
>
We see…
NO
movement
CONTRACTION
EXPANSION!!
NO
movement
BRIGHT - DARK
Gray
Rested neurons
Bright
Rested neurons
Gray
Tired DARK neurons
Gray
Rested neurons
DARK neurons
BRIGHT neurons
Compare BRIGHT & DARK
=
>
<
=
GRAY
DARK
BRIGHT
GRAY
We see…
COLOR
Which colors does the brain compare?
When the image is…
the after image is…
Red
Greenish
Blue
Yellowish
Green
Reddish
Yellow
Bluish
RED
Rested neurons
BLANK
Tired RED neurons
BLANK
Rested neurons
RED neurons
GREEN neurons
Compare RED & GREEN
>
<
=
We see…
RED
GREEN!!
BLANK
Try your to design
your own afterimage!
CELL COMMUNICATION
Activity developed during the 2009 Exploratorium Summer Institute “Class Menagerie” by:
Caltech Fellow Xoana Troncoso
and High School Teachers Patricia Dunlap, Robert Martin & Erick Roldan