surgical concepts in small intestine nutrition which has to be considered in bowel surgery care.

1. Nutrition
Dr. Timothy Wiyule Mutafya
COSECSA General surgery resident
Kamuzu central hospital

2.  Functional anatomy and histology
 Digestive physiology of main products
 Surgical vs nutritional significance
Dr Tim Mutafya

3. Anatomy
• Longest part of GIT from pylorus to ICJ
• Primary site for nutrient absorption
• It has three parts
• Duodenum, Jejunum and Ileum
• Total length 5.5 to 7m long
• Greater in male than females
• Small is not for size but diameter
• 2.5 – 3cm
• Surface area is 30square meters
• Main site for digestion and absorption
5%
<40%
<60%
Dr Tim Mutafya

4. Dr Tim Mutafya

5. • Macroscopic deep ridges in the mucosa
and submucosa.
• from proximal duodenum to middle
3rd of the ileum
• Their shape causes the chyme to spiral,
rather than move in a straight line
through the small intestine.
• slows the movement and provides the
time needed for nutrients to be fully
absorbed
1. Plica circulares
Dr Tim Mutafya

6. • Finger-like projections of the mucosa.
• Lie within circular folds
• 0.5–1 mm long
• about 20 to 40 villi per square mm
2. Villi
Dr Tim Mutafya

7. • Cylindrical apical surface extensions tiny extensions of the plasma membrane of
the epithelial cells that line the villi, forming a brush border that further enhances
absorption.
• Abt 200 million microvilli per square mm
3. Microvilli
Dr Tim Mutafya

8. Cells
Dr Tim Mutafya

9. Cell type Function
Enterocyte Digestion and absorption of nutrients in chime
Goblet
Secretion of mucus
Paneth Secretion of the bactericidal enzyme lysozyme; phagocytosis
G cells Secretion of intestinal gastrin
I cells Secretion of the hormone cholecystokinin (CCK)
K cells
Secretion of the hormone glucose-dependent insulinotropic
peptide
M cells Secretion of the hormone motilin
S cells
Secretion of the hormone secretin
Dr Tim Mutafya

10. Mechanical and Chemical
Dr Tim Mutafya

11. Mechanical digestion
Two types of movement
• Segmentation
• Migrating motility complex
Significance
1.Mixing of contents with digestive enzymes
2.Maximising exposure chyme to intestinal cells
3.Propulsin of contents to large intestines
Dr Tim Mutafya

12. 1.Segmentation
• Oscillating ring like contractions originating
from BER pacemaker cells in duodenum and
jejunum
• Parasympathetic stimulation by gastro-illeal
reflex
• Decreased by sympathetic stimulation
12/min in duodenum
9/min in ileum
Functions
1.Exposing chime to intestional
surface
2.Decrease rate of flow of chyme (3-5
hours
Dr Tim Mutafya

13. 2. Migratory motility complex (MMC)
• Begin in the duodenum, force chyme through a short section of the small intestine
and then stop.The next contraction begins a little bit farther down than the first,
forces chyme a bit farther through the small intestine, then stops
• Occurs in fasting state
• AKA house keeper
• Regulated by motilin
• Starts from the stomach
• About 90 to 120
min/cycle to reach
terminal ileum.
Dr Tim Mutafya

14. Carbohydrates, Lipids, Proteins
Dr Tim Mutafya

15. Chemical
digestion
Dr Tim Mutafya

16. Carbohydrates
Dr Tim Mutafya

17. lumen Epithelial cell/Enterocyte Blood
Dr Tim Mutafya

18. Glucose is absorbed by:
- sodium-dependent glucose transporter (SGLT)
- solvent drag
Lumen
Epithelial cell/Enterocyte
Blood
Dr Tim Mutafya

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20. LIPDS
Dr Tim Mutafya

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22. Proteins digestion
Dr Tim Mutafya

23. Digestion of
proteins
As stomach contents pass into duodenum,
the low PH triggers secretion of
hormones – SECRETIN and CCK
Secretin: bicarbonate pancreatic
secretion  pH From 1.5 -2.5 to 7.0
CCK: Stimulate pancreatic secretion
1. Endopeptidases:
Trypsin,chemotrypsin,elastase
2. Exopeptidases:
carboxypeptidases,aminopeptidases
The digestion products of hydrolysis by pancreatic enzymes is completed by intestinal peptidases
secreted by intestinal mucosa i.e. Aminopeptidase and dipeptidase
Dr Tim Mutafya

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27. Absorption
Intact proteins and polypeptides are absorbed Only infants absorbs
via endocytosis and pinocytosis BUT NOT adults
Amino acids are mostly absorbed via
Na+ dependnent active transport
through:
Na+/Amino acid cotransporter
Dr Tim Mutafya

28. Micronutrients
Dr Tim Mutafya

29. Vit B12 released from protein by action of
pepsin and HCL in the stomach
Vit B12 binds to IF from gastric parietal
cells forming IF-Cbl complex resist
digestion from GIT enzymes.
The complex is absorbed in terminal ileum
by pinocytosis
Vit B12 binds to transcobalamin in plasma
which transports it to the liver and other
used by cells
Dr Tim Mutafya

30. Summary
Dr Tim Mutafya

31. Short bowel syndrome
Dr Tim Mutafya

32. Short bowel syndrome (SBS) Clinically defined by malabsorption,
diarrhea, steatorrhea, fluid and electrolyte disturbances, and malnutrition
due to loss of ≥ 50 % (< 200cm viable) of structural and functional small
bowel
Dr Tim Mutafya

33. Functional impairment depends on
1. Length of intestine remaining
2. Condition of the remaining bowel
3. The absorptive quality of remnant bowel
4. Presence of ileocecal valve
5. Absence of colon
Loss of ileocecal valve
• transit time is faster, and increased loss of fluid and nutrients.
• Colonic bacteria colonize the small bowel, worsening diarrhea and nutrient loss
Dr Tim Mutafya

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35. prognosis Fair fair Good
J Parenter Enteral Nutr,
Volume: 38, Issue: 1S,
Pages: 14S-22S, 05
February 2014,
Dr Tim Mutafya

36. Intestinal adaptation
Morphologically
Macroscopic
• Increase in length
Microscopic
• Villus: increase height and diameter
• Crypt: elongation
• Epithelial cell life cycle: increase
proliferation
• Decrease apoptosis
Physiologically
• Increase absorption per unit length
• Upregulation of sodium glucose
transporter.
Dr Tim Mutafya

37. 24-48hrs
• Ostomy output > 5 L/d
(as high as 6-8 L/day)
• Life-threatening
dehydration and
electrolyte imbalances
• Extremely poor
absorption of all
nutrients
• Development of
hypergastrinemia and
hyperbilirubinemia
90% of
adaptations
Dr Tim Mutafya

38. Complications
Acute
1.Diarrhea
2.Malabsorption
3.Electrolyte imbalance
4.SAM
Late
1.Stones
• Oxalate renal stones
• Gallstones
2.Gastric hypersecretion
• Peptic ulcer
• Esophagitis
3.TPN related complications
4.Bacterial overgrowth
5.Chronic malnutrition
6.Liver failure
Dr Tim Mutafya

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40. Surgical intervention
Dr Tim Mutafya

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45.  Fish EM, Burns B. Physiology, Small Bowel. [Updated 2022 Oct 14]. In:StatPearls [Internet].Treasure
Island (FL): StatPearls Publishing; 2024 Jan-. Available from:
https://www.ncbi.nlm.nih.gov/books/NBK532263/Small Intestine Location, Function, Length and Parts
of the Small Intestine (healthjade.com)
 shortbowelsyndrome-150820110854-lva1-app6891.pdf
 Knipe H, Di Muzio B, Sharma R, et al. Jejunum vs ileum. Reference article, Radiopaedia.org (Accessed
on 01 Feb 2024) https://doi.org/10.53347/rID-43032
 J Parenter Enteral Nutr, Volume: 38, Issue: 1S, Pages: 14S-22S, 05 February 2014,
 Slideshare
 Iván Katime,William Sánchez-Maldonado, Jessica Pineda, Henry Henry Oliveros, Arturo
Vergara, Néstor Pedraza, Andrés Becerra, Sonia Carrero, Mauricio Francisco Duque, Manuel
Cadena, Consenso colombiano de Falla Intestinal Crónica en Síndrome de Intestino Corto, Revista
Colombiana de Cirugía, 10.30944/20117582.2425, (704-723), (2023).
 Guillen B, Atherton NS. Short Bowel Syndrome. [Updated 2023 Jul 17]. In:StatPearls [Internet].Treasure
Island (FL): StatPearls Publishing; 2024 Jan-.
Dr Tim Mutafya