3. YOU WILL ACHIEVE….
 To i d e n t i f y t h e p ar t s o f t h e
d i g e s t i ve s ys t e m i n vo l ve d i n t h e
ab s o r p t i o n o f d i g e s t e d f o o d ;
 To e x p l ai n t h e ad ap t i ve
c h ar ac t e r i s t i c o f t h e d i g e s t i ve
s ys t e m r e l at e d t o ab s o r p t i o n ;
 To d r aw & l ab e l t h e s t r u c t u r e o f a
vi l l u s ;
 To e x p l ai n t h e p r o c e s s o f ab s o r p t i o n
i n t h e vi l l us ;


4. A b s o r p t io n o f D ig e s t e d F o o d in
S m a ll In t e s t in e
 2 p r o c e s s o c c u r wh i c h ar e d i g e s t i o n &
ab s o r p t i o n
 Th e p r o c e s s o f d i g e s t i o n i s c o mp l e t e d
i n t h e i l e u m t o p r o d u c e s i mp l e s u g ar s ,
ami n o ac i d s , g l yc e r o l & f at t y ac i d s .
 Th e p r o c e s s o f ab s o r p t i o n al s o o c c u r s
i n t h e i l e u m t o ab s o r b t h e p r o d u c t s o f
d i g e s t i o n i n t o t h e b l o o d c ap i l l ar i e s &
t o b e u s e d b y t h e c e l l s i n t h e b o d y.
 Ab s o r b b y v i l l i ( s i ng ul ar : v i l l us ) i n
t h e wal l s o f t h e s mal l i n t e s t i n e . Eac h
vi l l u s c o n t ai n s a n e t wo r k o f b l o o d
c ap i l l ar i e s & a l ymp h c ap i l l ar y i n t h e

6. A d a p t a t io n o f
t h e s m a ll
in t e s t in e t o a id
a b s o r p t io n

7. LEARNING OUTCOMES
Explain the adaptive
characteristic of the
digestive system related
to absorption.

8.  I t i s l ong & coi l e d t o
i n c r e as e t h e s u r f ac e ar e a f o r
ab s o r p t i o n
 Th e l i n i n g o f t h e i n t e s t i n e
i s g r e at l y f o l d e d t o i n c r e as e
t h e s u r f ac e ar e a f o r
ab s o r p t i o n
 Th e e p i t h e l i al c e l l s l i n i n g
t h e vi l l u s i s ve r y t h i n t o

9.  Th e r e ar e man y vi l l u s &
mi c r o vi l l u s t o i n c r e as e
s u r f ac e ar e a f o r ab s o r p t i o n
 Eac h vi l l u s h as a n e t wo r k o f
b l o o d c ap i l l ar i e s t o t r an s p o r t
t h e d i ge s t e d f ood t h at h as
b e e n ab s o r b e d
 Eac h vi l l u s al s o h as l ac t e al
( l ymp h ve s s e l ) t o t r an s p o r t
g l yc e r o l & f at t y ac i d s .

11. S t r u c t u r e o f v illi

12. LEARNING OUTCOMES
Explain the process of
absorption in the villus.

14.  Blood capillaries at the villus absorb glucose
(simple sugar), amino acids, minerals, vitamins
B & C by simple diffusion through the
epithelium of the villus
 These substances are carried by the hepatic
portal vein to the liver & then distributed to
the body cells by the circulatory system
 The products of fats digestion such as glycerol &
fatty acids as well as vitamins A, D, E & K are
absorbed into the lacteal of villus

15.  Across the thin epithelium into the lacteal.
Once inside the lacteal, they recombine to
form fat droplets.
 The fat droplets & vitamins ADEK in the
lacteals are carried out of the ileum by a
lymph vessel called thoracic duct.
 Ileum  thoracic duct  left shoulder
vein (left subclavian vein)  bloodstream
 body cells

16.  The absorptive surface area of the small
intestine is roughly 250 square meters
- the size of a tennis court!!!

17. A B S O R P T IO N
OF
WA TE R
&
M IN E R A L S IN
C OLON

19.  Large intestine :
– Caec um : t h e p ar t wh e r e t h e
s mal l i n t e s t i n e j o i n s wi t h
t h e l ar g e i n t e s t i n e
– Col on : t h e l o n g e r p ar t o f
t h e l ar g e i n t e s t i n e
– Rec t um : t h e l as t p ar t o f
t h e l ar g e i n t e s t i n e

20.  F l u i d mat e r i al f r o m i l e u m
( n o t ab s o r b e d )  c ae c u m 
col on
 Col on abs or bs mu c h o f t h e
wat er f r o m t h e i n d i g e s t i b l e
f o o d r e s i d u e wh i c h b e c o me s
mo r e s o l i d as i t p as s e s
al o n g .
 Co l o n al s o abs or bs m ner al s
i
f r om t h e i nd i ge s t i b l e r e s i d u e

21. TRANSPORT
OF
NUTRIENTS BY
CIRCULATORY
SYSTEM

22. LEARNING OUTCOMES
Describe the transport of
nutrients by the circulatory
system for assimilation.

23.  Glucose + amino acids + minerals + vits. B & C
 blood capillaries of the villus  out of the
small intestine  liver (by the hepatic portal
vein)  the food molecules are transported
away to all the cells in the body by the blood
circulatory
 Glycerol + fatty acid + vits. A, D, E & K  the
lacteal of the villus  transport out of the
small intestine by the thoracic duct (lymph
vessel)  lymphatic system  at the left
shoulder, the thoracic duct joins the left
subclavian vein  bloodstream

24. A S S IM IL A T IO N B Y
B ODY C ELL
 Assimilation : the process where the
products of digestion are absorbed &
utilised in the body cells
 Used to synthesis complex molecules
required for growth, reproduction or
repair. (amino acids are used to synthesis
protoplasm of cells)
 Excess absorbed food molecules are stored
in the body

25.  Glucose = oxidised to produce energy in cell
respiration, excess  glycogen
 Amino acid = to synthesis enzymes,
antibody, plasma membrane & protoplasm,
excess  urea  urine (deamination)
 Lipids = to build plasma membrane &
cholesterol, excess  stored as adipose tissue
(under the skin, abdomen & internal organs as
kidneys, hearts)
 Minerals & vitamins = assimilated by the
body cells

26.  Minerals (calcium & phosphorus) 
build strong bone & teeth
 Iron  to synthesis haemoglobin in
the RBC, excess  stored in liver
 Vitamins A & D also stored in the
liver.

27. LEARNING OUTCOMES
Explain the
main function
of the liver
and describe
the process of
assimilation.

28. F U N C T IO N S O F T H E
L IV E R
 Th e l ar g e s t g l an d i n t h e
b o d y & c ar r i e s o u t man y
me t ab o l i c p r o c e s s e s
 Car r i e s o u t as s i mi l at i o n &
al s o ac t as a s t o r ag e o r g an
 Re c e i ve s t h e p r o d u c t s o f
d i g e s t i o n d i s s o l ve d i n t h e
b l o o d vi a t h e h e p at i c

29. M A IN F U N C T IO N S O F
T H E L IV E R
•Storage of nutrients
•Processing the products of digestion
•Detoxification
•Breakdowns of lipids in storage to provide
energy
•Production of bile
•Removal of damaged red blood cells
•Synthesis of vitamin A & blood clotting
substances
•Synthesis of plasma protein (fibrinogen,
prothrombin).

30. REGULATION OF BLOOD
GLUCOSE LEVELS
 Excess glucose  glycogen (present of
hormone insulin)  stores in the liver.
 Lack of glucose; glycogen  glucose by
hormone glucagons.

31. DEAMINATION
 Excess amino acids  liver  amino group
is removed (-NH2)  ammonia (toxic) 
urea  urine
 Remaining amino acids  carbohydrate or
fat.

32. STORAGE FUNCTION
 Stores vitamins A & D and B12.
 Some minerals : irons, potassium, cobalt,
zinc & copper.

33. DETOXIFICATION
 Bacteria  engulfed & destroyed by
phagocytic cells in the liver.
 Toxin  chemically modified  non-toxic 
eliminated.
 Cirrhosis  long time intake of large
quantities of alcohol @ viral diseases
(hepatitis)