1. Gastro-intestinal system II 2010

2. Structure Lamina mucosa
Epithelium (simple columnar or stratified squamous)
Lamina propria (loose collagenous connective tissue)
Lamina muscularis mucosae (smooth muscle)
Lamina submucosa (loose collagenous connective tissue)
Lamina muscularis externa (circular and longitudinal layer)
Lamina advetitia or serosa (mesothelium) – loose connective tissue

3. Pylorus

4. Pylorus

5. Duodenum

6. Small intestine
Duodenum
Brunner glands -mucous
Jejunum
Ileum

7. Small intestine Absorptive function – increase in the total surface:
Plicae circulares (circular folds) or valves of Kerkring (submucosa)
Intestinal villi (lamina propria)
Intestinal glands - Crypts of Lieberkühn (tubular glands)
Microvilli (cells)
Length – 4 – 6 m

8. Cells Enterocytes Goblet cells Paneth cells Neuroendocrine Cells
M-cell
Stem cells
Intraepithelial lymphocytes

9. Enterocytes
Resorption – brush border – microvilli (actin, villin, calmodulin)- terminal web
Surface coat – glycocalyx
Enzymes – disacharidases, aminopeptidases
Fatty acid binding protein (FABP) - SER- resynthesis – GA - chylomicrons
Na+, K+ ATPase

10. Brush border Actin microfilaments Terminal web
Binding to the membrane in the villus and zonula adherens
Intermediate fillament

11. Goblet cell
Production of mucus – RER and CA - glycoproteins – exocytosis
Protective gel coat – again mechanical abrasion and bacterial invasion

12. Enteroendocrine cells
Diffuse endocrine – paracrine gland
Cholecystokinin
Secretin
Gastrin
Serotonin
Somatostatin
VIP, substance P, GIP
Glucagon-like factor

13. Paneth cells
Granules:
Lysozyme
TNFα
Defensins
(Nonspecific immunity)

14. Villi Outhgrowths of lamina mucosa Smooth muscle cells
Fenestrated blood capillaries
Lymphatic capillaries

15. Plexus myentericus

16. Protection of small intestine
Peyer´s patches – gut associated lymphoid tissue – GALT
Dome (antigen-presenting cells) and germinal centre
Follicle associated epithelium – M-cells – transport of antigens to the antigen presenting cells
Plasma cells – secretory IgA dimers – transcytosis – secretory component

17. Medical application
Deficiencies of disaccharidases (genetic, infection, alergy to gluten) – malabsorption syndrome
High rate of cell renewal (3-7 days) – affected by chemotherapy or X-ray exposure - diarrhea

18. Colon No Paneth cells No villi, no plicae circulares
Resorption of water
and ions:
Colonocytes
Goblet cells and enteroendocrine cels
No Paneth cells

19. Colon
Teniae coli – longitudinal bands of external longitudinal layer of smooth muscle.
Appendices epiploicae: serosa forms pendulous processes – adipose tissue

21. Medical aplications
90 -95% of malignant tumors of the digestive tract are derived from epithelium.
Stomach or large intestinum – glandular cells – adenocarcinoma
Very frequent

22. Apendix Structure as colon However
Muscularis externa is continuous it does not form tenia colli
In lamina propria and submucosa, there is abundant lymphatic tissue (tonsilla abdominalis)
Paneth´s cells could be present in crypts of Lieberkűhn

23. Apendix