TARSUS
c a n n o t
c l o s e
t h e i r
e y e s
o r
t h o s e w i t h
e x o p h th a lm o s
( b u l g i n g e y e s ) . T h e e y e l i d s
a r e l a t e r c u t a p a r t a n d a l l o w e d t o o p e n .
ta rs u s
T h e s e v e n b o n e s t h a t m a k e u p t h e b a c k o f
t h e f o o t a n d t h e a n k l e .
ta rta r
S e e
c a lc u lu s , d e n ta l.
ta rtra z in e
A y e l l o w d y e t h a t i s c o m m o n l y u s e d a s
a f o o d c o l o u r i n g i n s o f t d r i n k s , c o n f e c -
t i o n e r y , a n d
r e a d y - p r e p a r e d
m e a l s .
( S e e
a l s o
f o o d a d d itiv e s.)
ta ste
O n e o f t h e f i v e s e n s e s . T a s t e c a n d i s t i n -
g u i s h
b e t w e e n
s w e e t ,
s a l t ,
s o u r ,
a n d
b i t t e r , b u t i n c o m b i n a t i o n w i t h t h e s e n s e
o f
s m e ll,
m a n y d i f f e r e n t f l a v o u r s c a n b e
d i s t i n g u i s h e d . A f i f t h t a s t e , u m a m i , h a s
n o w b e e n r e c o g n i z e d . T a s t e s a r e d e t e c -
t e d b y s t r u c t u r e s c a l l e d
ta ste b u d s .
ta s te b u d
O n e
o f
1 0 , 0 0 0
s p e c i a l i z e d
s t r u c t u r e s
l o c a t e d
m a i n l y
o n
t h e
to n g u e ,
w i t h
s o m e a t t h e b a c k o f t h e t h r o a t a n d o n
t h e p a l a t e . E a c h b u d c o n t a i n s a b o u t 5 0
s e n s o r y
r e c e p t o r
c e l l s ,
w i t h
t i n y
t a s t e
h a i r s t h a t r e s p o n d t o
f o o d a n d d r i n k .
T a s t e
b u d s
o n
d i f f e r e n t
p a r t s
o f t h e
t o n g u e s e n s e t h e f i v e b a s i c
ta ste s:
b i t t e r ,
s o u r , s a l t y , s w e e t , a n d u m a m i .
ta ste , lo s s o f
L o s s o f t h e s e n s e o f
ta ste ,
u s u a l l y a s a
r e s u l t o f l o s s o f t h e s e n s e o f
s m e ll.
T h e
m o s t c o m
m
o n c a u s e i s i n f l a m m a t i o n o f
t h e n a s a l p a s s a g e s . O t h e r c a u s e s i n c l u d e
a n y c o n d i t i o n t h a t c a u s e s a d r y m o u t h
( s e e
m o u th , d r y );
n a t u r a l
d e g e n e r a t i o n
o f t h e
ta ste b u d s
w i t h a g e ;
d a m a g e t o
t h e t a s t e b u d s f r o m
s to m a t it is
( i n f l a m -
m a t i o n o f t h e m
o u t h ) ,
m o u th c a n c e r,
o r
ra d io t h e ra p y
t o t h e m o u t h ; o r d a m a g e t o
n e r v e s t h a t c a r r y t a s t e s e n s a t i o n s .
T
THE SENSE OF TASTE
Tastes are detected by special structures, which are called
taste buds. Every person has some 10,000 taste buds, mainly
situated on the tongue, with a few at the back of the throat
and on the palate. These taste buds surround pores within
papillae (protuberances) on the tongue surface and elsewhere.
There are five types of taste buds (sensitive to sweet, salty,
sour, bitter, and umami chemicals). All tastes are formed from
a mixture of these five elements.
Olfactory
bulb
Glosso-
pharyngeal
Vallate
papillae -
Vallate
papilla
Taste
pore
Filiform
papillae
Fungiform
papillae
Taste bud
How a substance is tasted
Chemicals in food or drink dissolve in saliva
and enter pores in the papillae on the tongue.
Around these pores are groups oftaste
receptor cells - the taste buds. The chemicals
stimulate hairs projecting from the receptor
cells, causing signals to be sent from the cells
along nerves to taste centres in the brain.
Magnified photograph of tongue surface
This photograph shows large (fungiform) and small
(filiform) papillae. Taste buds are arranged around
pores in the surface ofthe papillae.
Fungiform papillae
These mushroom-
shaped papillae
occur in small
numbers at random
over the tongue
surface, mainlyat
the tip and sides.
Filiform papillae
These smaller
peak-shaped
protuberances occur
in large numbers
over all except the
back ofthe tongue’s
upper surface,
and on the palate.
TASTE CENTRES
Taste buds sensitive to sweet,
salty, sour, or bitter are grouped
in particular areas on the surface
ofthe tongue. The areas sensitive
to umami are not yet known.
\ (
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<,>J
Bitter
V
* 'I
Ш
. ;
; 7
\
І
'і.' •
.
/
sour
Salt
V
T
V
Sweet
730
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