Page 47 - (DK) How to be a GENIUS?

Sensory map
This odd-looking figure
shows how your brain
reacts to touch on various
parts of your body. It looks
strange because the size of each
m
body part is related to the number
t
of touch sensors that it has rather
Hair shaft Proje ects
n
above skin surf face than its physical size. Your hands are
and reacts to to ouch
and air moveme ent shown much bigger than your feet
s
because they are much more sensitive.
Epidermis
Outer layer
e
e
s
el
e
e
n
e
e
e
e
e
e
t
a
t
eas
l
l
e
ea
ea
The least sensitiveve
ve
v
T Th Th
t
tive
t
t
t
s
h
n
of skin The le a s t sen s i i i t i i v e
y
f
o
o
o
d
o
f
y
y
d
o
u
o
ody
ur
r
r
b
b
u
o
o
o
o
o
o
u
o
o
t
t
r
rt
o
o
t
o
r
a
a part
part of y o u r b o d y
part of yoour body
r
rt
a p
rt

d
dd
d
s i i i
s
d
ddl
i
i
i
i
d
t
i
e
e
e
o
f of f
f
o
e
l
l
is the miiddle of
e
e
e
e
t
m
h
h
m
the
u
a
k
r
o y
c
u
k
r
your bback.
b
b
ba
b
b
b
b
y your b a c k . .
u
o
Habituation
Although your brain
reacts strongly to new
Dermis Contains s
blood vessels, sensory information from your skin,
glands, and it adapts to some constant or repetitive
nerve endings
messages to make them less distracting.
This effect happens with all the senses
but is most easily tested using touch.
Meissner’s corpu uscle
A touch receptor If you put a pencil in the palm of your
found in sensitive e hand, for example, you get an instant
areas of skin
sensation, but within seconds this wears
off to leave just a low-key awareness.
This is because some skin sensors soon
stop sending signals, but others don’t.
Pacinian corp puscle
Sensitive to
pressure and
vibrations
g pain
Feeling
Nerve endings throughou t your skin
t
register pain by reacting to c
chemicals
mines that
called prostaglandins and histam
fr
e

ar
are released from damaged cce

ge
d

om
r
el

e
ells. There
eased
dama
s
are two types of pain respon ses. One is
u
short and sharp to make yo u jerk your
hand away from a candle flam e in a reflex
action. The other is slower and d starts after
the reflex, giving more pers istent pain and
ble long-term harm.
warning us of possib
45
(c) 2011 Dorling Kindersley. All Rights Reserved.