DIGESTION
D
THEDIGESTIVE PROCESS
Digestion starts when food enters the
mouth. It continues as the food is
propelled through the digestive tract
by waves ofmuscular contractions
(peristalsis). The digestive process also
involvesvarious organs (the salivary
glands, liver, gallbladder, and pancreas),
which produce enzymes and acids that
help to break down the food.
Swallowing
In the mouth, food is cut
and ground bythe teeth
and mixed with saliva,
which softens it and
breaks down certain
carbohydrates. After
swallowing, the food
mass (bolus) entersthe
oesophagus.
ACTION OF DIGESTIVE AGENTS
Agent or enzyme
(where produced)
Digestive
action
Amylase
(mouth and pancreas)
Converts starch
(a carbohydrate)
to maltose
Sucrase, maltase,
and lactase
(pancreas and small
intestine)
Breakdown
vegetable and
milk sugars into
glucose, fructose,
and galactose
Hydrochloric acid
(stomach),
Pepsin (stomach),
Trypsin (pancreas),
Peptidase
(small intestine)
Assist in the
breakdown of
proteins into
polypeptides,
peptides, and
amino acids
Lipase (pancreas)
Bile salts and acids
(liver - stored in the
gallbladder)
Break down fats
into glycerol and
fatty acids
O e s o p h a g u s
F o o d i s c a r r i e d d o w n
t h e o e s o p h a g u s b y
p e r i s t a l t i c a c t i o n a n d
e n t e r s t h e s t o m a c h .
S t o m a c h
F o o d is b r o k e n d o w n
f u r t h e r b y c h u r n in g
a n d b y t h e a c t i o n o f
h y d r o c h l o r i c a c i d a n d
d i g e s t i v e e n z y m e s
s e c r e t e d b y t h e
s t o m a c h l in in g .
F o o d r e m a i n s in t h e
s t o m a c h u n t il i t is
r e d u c e d t o a s e m i -
l i q u i d c o n s i s t e n c y
( c h y m e ) , w h e n it
p a s s e s in t o t h e
d u o d e n u m .
D u o d e n u m
_______
T h is i s t h e f i r s t p a r t o f
t h e s m a l l in t e s t i n e .
As
f o o d t r a v e l s t h r o u g h
t h e d u o d e n u m , it is
b r o k e n d o w n f u r t h e r
b y d i g e s t i v e e n z y m e s
f r o m t h e liv e r , t h e
g a l l b l a d d e r , a n d
t h e p a n c r e a s .
S m a l l i n t e s t i n e
_____
A d d i t i o n a l e n z y m e s
s e c r e t e d b y g l a n d s in
t h e lin in g o f t h e s m a l l
i n t e s t i n e c o m p l e t e t h e
d i g e s t i v e p r o c e s s .
N u t r i e n t s a r e a b s o r b e d
t h r o u g h t h e i n t e s t in a l
lin in g in t o t h e n e t w o r k
o f b l o o d v e s s e l s a n d
l y m p h v e s s e l s t h a t
s u p p l y t h e i n t e s t in e .
U n d i g e s t e d m a t t e r
p a s s e s in t o t h e l a r g e
i n t e s t i n e ( t h e c o lo n ) .
C o l o n
____________
W a t e r f r o m u n d i g e s t e d
m a t t e r i s a b s o r b e d
t h r o u g h t h e lin in g o f
t h e c o l o n . T h e r e s i d u e
p a s s e s in t o t h e r e c t u m .
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