Intestines

Question 1

General Plan of GI tract

Answer 1

-Mucosae (epithelium, 
lamina propria, muscularis mucosae  
-Submucosae 
-Muscularis Externa
-Adventitia (CT) or Serosa  (CT and epithelium)

Question 2

Structures responsible for the increased surface of the small intestine

Answer 2

plicae circulares (folds of submucosa)
Villi (folds of mucosa)
Crypts of Lieberkuhn (Glands)
Microvilli with glycocalyx

Question 3

A jejunum with celiac’s disease will have

Answer 3

more connective tissue with lymphocytes

Question 4

Duodenum characteristics

Answer 4

-Brunner’s gland
(in submucosa)
-Distal part: numerous plicae circulares

Question 5

Jejunum char

Answer 5

• Numerous plicae circulares
• Numerous villi
• no glands in submucosa
• no Payer’s patches

Question 6

Ileum char

Answer 6

Peyer’s patches (M cells)

Middle part: reduced number and size of plicae circulares

Question 7

Mucosa of the small intestine

Answer 7

villi – mucosal projections containing lacteal
crypts of Lieberkühn – intestinal glands in the mucosa
epithelium: simple columnar (covers villi and crypts)
Gut Associated Lymphatic Tissue (GALT) in the lamina propria
Mucosa and submucosa
-plicae circulares

Question 8

Small Intestine: Epithelium- Cell types

Answer 8

absorptive cells 
goblet cells
Paneth cells
enteroendocrine cells 
M cells (microfold cells) 
stem cells – regenerative cells

Question 9

absorptive cells

Answer 9

with microvilli –brush/striated border with glycocalyx, contain enzymes

Question 10

goblet cells

Answer 10

unicellular mucin-secreting glands (high number in the ileum)

Question 11

Paneth cells

Answer 11

(in the crypts), secretion: antibacterial lysozyme. Paneth cells play a role in regulation of normal bacterial flora of the small intestine (absent in large intestine).

Question 12

enteroendocrine cells

Answer 12

hormones secretion: gastrin, cholecystokinin (CCK), secretin, gastric inhibitory peptide (GIP), somatostatin, vasoactive intestinal polypeptide (VIP), motilin, enteroglucagon

Question 13

M cells (microfold cells)

Answer 13

cover enlarged lymphatic nodules, e.g., Peyer’s patch, transport antigens.

Question 14

Large intestine summary

Answer 14

no villi, no folds
many glands – crypts of Lieberküh
lamina propria: thick layer of collagen, GALT present (M cells), no lacteal
- Submucosa
-no plicae curculares
- Muscularis externa
-inner circular layer (thin)
-outer longitudinal layer has three bands (teniae coli)

Question 15

Large Intestine: cell types

Answer 15

Epithelium: simple columnar
A large number of commensal bacteria are found in the large intestine and oral cavity.
Absorptive cells with microvilli and glycocalyx (no digestive enzymes)
Goblet cells (higher number in the lower colon)
Enteroendocrine cells
Stem cells (regenerative cells)
No Paneth Cells

Question 16

Large Intestine: Ulcerative Colitis

Answer 16

Mucosa is lost over extensive area, with ulceration and destruction of the absorptive epithelium. results in diharrea

Question 17

Appendix summary

Answer 17

• Epithelium: absorptive cells and M cells, few goblet cells.
• Lymphatic nodules: in mucosa and submucosa
• Muscularis externa: thick inner circular layer and outer longitudinal layer, no teniae coli

Question 18

Anal Canal epithelium

Answer 18

Stratified squamous

epithelium

Question 19

Colon, Rectum epithelium

Answer 19

simple columnar

epithelium

Question 20

anal skin

Answer 20

keratinizing stratified squamous