ALimentary 2: Intestines

Question 1

small intestine includes

Answer 1

• duodenum
• jejunum
• ileum

Question 2

characteristics of the small intestine

Answer 2

• villi/microvilli
• plica circulares
• goblet cells
• crypts (intestinal glands)

Question 3

large intestine includes

Answer 3

• cecum
• appendix
• colon

Question 4

characteristics of the large intestine

Answer 4

• no villi
• many goblet cells
• crypts
• teniae coli

Question 5

pyloric sphincter seperates what?

Answer 5

stomahc and duodenum

Question 6

what type of tissue makes up the innards of a villi

Answer 6

-lamina propria

Question 7

muscularis mucosa of the small intestine

Answer 7

• inner circular

- outer longitudinal

Question 8

duodenum

Answer 8

• villi forming

- submucosal glands, Brunners, secrete alkaline mucous to neutralize acid chyme

Question 9

specializations of the villi for digestion

Answer 9

• smooth muscle:
• lymphatic capillary (central lacteal)
• epithelium: controlled absorption

Question 10

celiacs disease

Answer 10

• inflammatory response to gluten protein

- glycocalyx and microvilli structure is disrupted (atrophy) leading to malabsorption

Question 11

microvilli and epithelial glycocalyx

Answer 11

• concentrates active enzymes

- local activation of trypsinogen to trypsin via enterokinase/enteropeptidase

Question 12

anchored enzymes in the glycocalyx

Answer 12

• trypsin
• chymotrypsin
• elastase
• nuclease

Question 13

digestive products of the microvilli/glycocalyx

Answer 13

• active transport into cell
• release on basolateral surface
• transport to liver

Question 14

abortion of lipids into the lymphatics

Answer 14

1. fat globules are emulsified by bile salts
2. emulsion droplets are digested by lipases into free FA’s
3. more bile salts bind to the FFA’s and creates micelles
4. TAG’s are then absorbed into the epithelial cells
5. TAGs are then packaged into chylomicrons and secreted into the lacteals within villi

Question 15

crypts

Answer 15

• invaginations into mucosa
• crypts of lieberkuhn
• surrounded by lamina propria
• contain: goblet cells, paneth cells, enteroendocrine cells, stem cells

Question 16

goblet cell concentration increases as

Answer 16

-you go down the intestinal tract

Question 17

paneth cells

Answer 17

• highly eosinophilic granules

- antimicrobial products: lysozymes, alpha-defensins

Question 18

enteroendocrine cells

Answer 18

• diffuse neuroendocrine system
• gastrin
• somatostatin
• ghrelin
• CCK
• secretin
• open type regulated by luminal contents
• closed type regulated by neural and paracrine mechanisms
• both types secrete basally into ECM, fenestrated caps

Question 19

stem cells

Answer 19

-generates all four cell types found: eterocyte, goblet, enteroendocrine, paneth

Question 20

turnover of stem cells

Answer 20

• 5-6 days

- this rapid rate renders the cells susceptible to many cancer therapies that target rapidly dividing cells

Question 21

jejunum

Answer 21

• plicar circulares (infolding of submucosa)
• peyers patch
• microfold cells

Question 22

muscularis externa

Answer 22

• all small intestine has inner circular/outer longitudinal layers
• seperated by myenteric (auerbachs plexus)

Question 23

serosa

Answer 23

• visceral peritoneum

- covers most of the small intestine

Question 24

colon

Answer 24

• no villi**
• many crypts (IGs)
• abundant goblet cells
• few/no paneth cells
• enteroendocrine
• tenia coli

Question 25

serosa and adventitia cover…

Answer 25

the large intestine