The document provides information on the absorption of nutrients including carbohydrates, proteins, fats, vitamins, and minerals in the small intestine. It discusses the transport mechanisms and proteins involved in absorbing each nutrient. Carbohydrates like starch are broken down into monosaccharides like glucose which are then absorbed via sodium-glucose transport proteins. Proteins are broken down into amino acids and absorbed via sodium-dependent and independent transporters. Fats are formed into micelles then absorbed via cholesterol ester transport proteins to form chylomicrons. Water and electrolytes like sodium and bicarbonate are also absorbed via various transport mechanisms in the small intestine.

2. TIMELINE
2019
DISORDERS
3
ABSOPTION OF FATS
1
ABSOPTION OF
CRBOHYDRATES
ABSORPTION OF
PROTEINS
2
OTHERS
4

3. DIETARY CARBOHYDRATES
MALTOSE SUCROSELACTOSE
SALIVARY AMYLASE
PANCREATIC AMYLASE
STARCH & GLYCOGEN
GALACTOSE GLUCOSE GLUCOSE GLUCOSE FRUCTOSE GLUCOSE
GLYCOSIDASE SUCRASE-ISOMALTASE COMPLEXGLUCOAMYLASE

4. GALACTOSE GLUCOSE GLUCOSE
S
G
L
T
1
S
G
L
T
1
S
G
L
T
1
S
G
L
T
1
S
G
L
T
1
G
L
U
T
5
S
G
L
T
1
S
G
L
T
1
GLUCOSE
FRUCTOSE
FRUCTOSEGALACTOSE GLUCOSE
22 2
SGLT-1
GLUT-5
GALACTOSE
GLUCOSE FRUCTOSE

5. Na+
Glu
Na+
Glu
3Na+3Na+
2K+
2K+
Na+-K+ ATPase
Na+
Glu
GLUT-2
Decrease Na+
concentration
SGLT-1
Glu
Glu
Glu
Glu

6. ABSOPRION OF PROTEINS
� Cotransport amino acid
and Na+ in similar fashion
to the cotransport of Na+
and glucose
REQUIRE Na+
� 2 of these also require
Cl-
Na+ INDEPENDENT
SMALL NEUTRAL AMINO ACID
Proton dependent Amino
acid Transporter
• Dipeptide and tripeptide
• REQUIRE H+ INSTEAD OF
Na+
Pep T-1 5
7
TRANSPORT
SYSTEM
2

7. NEUTRAL
AMINO ACID
AMINO ACID
P
A
T
P
E
P
T
1
AMINO ACID
DI-PEPTIDE &
TRI-PEPTIDES
DI & TRI
PEPTIDES
AMINO ACID AMINO ACID
AMINO ACID
AMINO ACID AMINO ACID
BASOLATERAL MEMBRANE

9. 50%
25%
25%
Source of digested food
Ingested food Digestive juices
Desquamated mucosal cells
• ABSOPTION IS RAPID IN DUODENUM AND
JEJUNUM
• 2-5% escapes digestion and absorption
• HARTNUP DISEASE: Neutral amino acid
transporter in small intestine and kidney
nonfunctional congenitally
• Tryptophan – niacin, serotonin
• CYSTINURIA: congenital defect in transport
of basic amino acid & cystine
• Infants: moderate amount of
undigested proteins also absorbed
• Decline sharply after weaning

10. MICELLE
Vit-A, K, E, D
Cholesterol
PL
COATED WITH
LIPOPROTEINS
CHYLOMICRON
MCFA
L
A
C
T
E
A
L
C
A
P
I
L
A
R
R
Y
APO-B48

11. FATTY ACID + Co-A ACYL Co-A
ACYL Co-A + MONOGLYCERIDE DIGLYCERIDE
ACYL Co-A + DIGLYCERIDE TRIGLYCERIDE
SMOOTH ER
Acyl Co-A synthetase
CHOLESTEROL(2%)
APOPROTEIN(1%)
PHOSPHOLIPID
(7%)
CHYLOMICRON
MG acyl transterase
DG acyl transterase
DHAP or PHOSPHORYLATED GLYCEROL
2 mol Co-A fatty acid
+
PHOSPHATIDIC ACID DIGLYCERIDE
PO4
-
Phosphatidic acid pathway
MG Acylation pathway

12. Short chain fatty acid
2-5 Carbon weak acid
Colonic bacteria:
carbohydrates
60% acetate
25% propionate
15% butyrate
Produced and absorbed in colon
Absorbed SCFA make significant
contribution in total caloric
intake
Trophic effect on colonic
epithelial cell and combat
inflammation
Absorbed in exchange with H+
AND help to maintain acid base
equilibrium

13. Na+Na+
H+ H+ HCO3
_
_
+
H2CO3
CO2 + H2OCO2
ABSORPTION OF BICARBONATE IONS
ENTEROCYTE
CO2

14. Na+
Na+ (142 meq/L)
(50meq/L)
Na+Na+
H2O
H2O
H2O
H2O
H2O H2O
Na+
H2O
E
N
T
E
R
O
C
Y
T
E
H2OH2O

15. I
R
O
N
Ferric reductase
Heme oxygenase
Hephaestin

16. VITAMINS
• Most vitamins are absorbed into upper small intestines except B12
WHICH is absorbed into the ileum
• This vitamin first bind with intrinsic factor secreted from parietal
cell of the stomach and the complex is the form which absorbed in
ileal mucosa
• B-12 and Folate are Na+ independent but all remaining water
soluble vitamins are absorbed by carrier that are Na+
cotransporter

17. THANK YOU