Histology of the Small and Large Intestine

Question 1

How do nerves, blood vessels and lymphatic vessels reach the alimentary canal?

Answer 1

• Mesenteries
• Adjacent connective tissue (tunica adventitia in retroperitoneal organs)

Question 2

Where are mucosal glands found in the alimentary canal?

Answer 2

• Throughout length
• Sparingly in oral cavity + oesophagus

Question 3

Where are submucosal glands found in the alimentary canal?

Answer 3

• Oesophagus
• Duodenum

Question 4

Where are villi found in the alimentary canal?

Answer 4

Small intestine

Question 5

Where are lymphoid tissue/nodules found in the alimentary canal?

Answer 5

Lamina propria of entire length

Question 6

General tissue layers of alimentary canal

Answer 6

• Epithelium
• Lamina propria
• Muscularis mucosa
• Submucosa
• Inner circular muscular layer
• Outer longitudinal muscular layer
• Serosa

Question 7

Distinct features of the duodenum

Answer 7

• Brunner’s glands (submucosa)
• Broad, leaf-like villi
• Plicae circulares not obvious
• Paneth cells not readily observed
• Low number of goblet cells
• Lymphoid tissue fairly inconspicuous

Question 8

Distinct features of the jejunum

Answer 8

• Submucosal glands absent
• Long, finger-like villi
• Plicae circulares begin to appear
• Paneth cells found at base of glands of Lieberkühn
• Moderate number of goblet cells
• Moderate amount of lymphoid tissue

Question 9

Distinct features of the ileum

Answer 9

• Submucosal glands absent
• Short, finger-like villi
• Prominent plicae circulares
• Paneth cells found at base of glands of Lieberkühn
• Goblet cell numbers highest
• Prominent lymphoid tissue seen in Peyer’s patches

Question 10

What type of epithelium lines the mucosa of the small intestine?

Answer 10

Simple columnar epithelium

Question 11

Major cell types contained in the epithelium of the small intestine

Answer 11

• Enterocytes
• Goblet cells
• Enteroendocrine cells
• Paneth cells
• Tuft cells
• Intestinal stem cells

Question 12

Features/functions of enterocytes

Answer 12

• Absorptive
• Columnar with apical microvilli
• Glycocalyx coats microvilli (glycoproteins involved in digestive process)

Question 13

Features/functions of enteroendocrine cells

Answer 13

Produce gastrin, secretin + cholecystokinin

Question 14

Features/functions of Paneth cells

Answer 14

Produce several antimicrobial proteins (AMPs)

Question 15

Features/functions of tuft cells

Answer 15

Increase in number in response to intestinal parasite infection

Question 16

What are intestinal villi surrounded by?

Answer 16

At least 6 crypts of Lieberkühn

Question 17

What do crypts of Lieberkühn contain and for what purpose?

Answer 17

• Intestinal stem cells (ISCs)
• Maintain epithelial lining of villus + crypt

Question 18

What do Brunner’s glands secrete and into where?

Answer 18

• Mucous
• Crypts of Lieberkühn via excretory ducts

Question 19

Degrees of folding in the small intestine

Answer 19

• 1st = plicae circulares
• 2nd = villi
• 3rd = crypts of Lieberkühn
• 4th = microvilli

Question 20

What does the mucosa of the large intestine contain?

Answer 20

Crypts of Lieberkühn

Question 21

Cells present in the mucosa of the large intestine

Answer 21

• Simple columnar absorptive enterocytes with apical microvilli
• Predominantly goblet cells
• Enteroendocrine cells

Question 22

What does the outer longitudinal muscular layer of the large intestine form and what for?

Answer 22

• 3 band of smooth muscle called taeniae coli
• Aid in peristaltic movement of faeces

Question 23

Epithelial change from rectum to anus

Answer 23

Simple columnar –> stratified squamous

Question 24

Where does the longitudinal muscle layer of the alimentary canal stop, and what is it replaced by?

Answer 24

• At pelvic diaphragm
• Replaced by external anal sphincter