Shut your eyes. What can
you feel? Touch, pressure, heat, or cold? All these sensations are
your brain's interpretation of signals it receives from your skin.
Here's a simple exploration you can do to measure your sense of
In this activity you'll
explore National Science Education Content Standard C: Life Science
- Structure and function
perform specialized functions in multicellular organisms. Groups
of specialized cells cooperate to form a tissue, such as a muscle.
Different tissues are, in turn, grouped together to form larger
functional units, called organs. Each type of cell, tissue, and
organ has a distant structure and set of functions that serve the
organism as a whole.
is one kind of response an organism can make to an internal or environmental
stimulus. A behavioral response requires coordination and communication
at many levels, including cells, organ systems, and whole organisms.
Behavioral response is a set of actions determined in part by heredity
and in part from experience.
animals have nervous systems that generate behavior. Nervous
systems are formed from specialized cells that conduct signals rapidly
through the long cell extensions that make up nerves. The nerve
cells communicate with each other by secreting specific excitatory
and inhibitory molecules. In sense organs, specialized cells detect
light, sound, and specific chemicals and enable animals to monitor
what is going on in the world about them.
What You'll Need:
- Two "picks" used for
hair rollers or the ends of two paper clips that you've partially
- A millimeter ruler
- Eye protection
Whenever there is a chance
of any object coming near the eyes wear eye protection. Don't forget
to wash or sterilize it between uses.
Find a partner. Ask your
partner to shut his or her eyes. Then very gently place two points
on the skin on the back of your partner's hands, 5 mm apart.
Ask: "Can you feel two points or one?" (Most students will be able
to tell that there are two points.)
Next, try to find the
minimum distance that a student can distinguish two points instead
of one. Do this by trying to place your points 4 mm apart,
then 3 mm, 2 mm, and 1 mm from each other. Record
your subject's response on the table below.
Next try the same experiment
on the top and bottom of the forearm. Is there a difference?
Finally, ask your partner
to put on eye protection (just in case!) and try it on the cheek.
Points or One?
Area of body:
|Back of hand
||Top of forearm
||Bottom of forearm
| 5 mm
| 4 mm
| 3 mm
| 2 mm
| 1 mm
1. In which area of the
skin are touch receptors closest?
2. What is the survival
value of touch receptors?
3. Is there any part of
the body where touch receptors would be a disadvantage?
1. The top of the forearm
and the cheek are most sensitive to a light touch.
2. Response to danger and
a soothing effect in the young (releasing brain endorphins) are
3. The soles of the feet
would be one area.