GI tract II

Question 1

where is the most common place for pathologies of the GI tract to arise?

Answer 1

at junctions

Question 2

what are rugae?

Answer 2

folds in the stomach that allow for expansion when eating

Question 3

what is the epithelium present in the stomach?

Answer 3

simple columnar and mucus cells (not goblet cells)

Question 4

what are gastric pits?

Answer 4

openings of the gastric glands, present in the lamina propria, also called faveolae

Question 5

what are the 4 regions of the stomach?

Answer 5

cardia, fundus, body, pylorus

Question 6

what is contained in the cardiac region of the stomach?

Answer 6

cardiac glands that secrete mucus

Question 7

what is the gland architecture of the fundic region of the stomach?

Answer 7

• surface- mucus cells
• isthmus- short, cellular replication site with undifferentiated cells, mucus cells migrate up and glandular cells migrate down
• neck- long
• base

Question 8

where are mucus neck cells found?

Answer 8

funds of stomach

Question 9

what is the role of mucus neck cells?

Answer 9

influence by vagal nerve, produces mucus secretion that traps bicarb and protects cells from acidic environment

Question 10

where are chief cells found?

Answer 10

fundus of stomach

Question 11

what is the appearance of chief cells? role?

Answer 11

basophilic d/t high RER, secrete pepsinogen and weak lipase

Question 12

what is pepsinogen?

Answer 12

zymogen, converted to pepsin (protease) after contact with HCl

Question 13

where are parietal cells found?

Answer 13

neck/fundus of stomach

Question 14

what is the role/appearance of parietal cells?

Answer 14

appear as triangular, eosinophilic d/t high mitochondria content, produce H+ and Cl-; also secrete intrinsic factor

Question 15

what triggers secretion of Hcl from parietal cells?

Answer 15

gastrin, via + feedback mechanism

Question 16

what is the role of HCl in the stomach?

Answer 16

destroys pathogens
initiated protein digestion
activates pepsinogen

Question 17

what is the role of intrinsic factor?

Answer 17

needed for B12 absorption in the small intestine

Question 18

where are enteroendocrine cells found?

Answer 18

fundus of stomach, resting of basal lamina

Question 19

what is the appearance and function of enteroendocrine cells?

Answer 19

small cells with clear cytoplasm; secrete gastrin

Question 20

what is the characteristic appearance of the fundic stomach?

Answer 20

short pits

long glands

Question 21

what is the characteristic appearance of the pyloric region of the stomach?

Answer 21

long pits

short glands

Question 22

what is contained in the glands of the pyloric region?

Answer 22

mostly mucus cells, few parietal and enteroendocrine cells

Question 23

what is unique about the muscularis externa layer of the stomach?

Answer 23

contains an oblique layer
inner- oblique
middle- circular
outer- longitudinal

Question 24

what layer of the stomach forms the pyloric sphincter?

Answer 24

middle circular layer of the muscularis externa

Question 25

what is the outermost layer of the stomach?

Answer 25

serosa, continuous with omentum

Question 26

what should you look for at the gastro-esophageal junction?

Answer 26

transition between the stratified squamous non-keratinized epithelium of the esophagus and the simple columnar epithelium of the stomach

Question 27

what is the histologic appearance of parietal cells?

Answer 27

"fried egg", acidophilic d/t high mitochondria

Question 28

what is the histologic appearance of chief cells?

Answer 28

basophilic d/t high RER

Question 29

what type of gland is unique to the duodenum?

Answer 29

Brunner's Glands

Question 30

what structure is unique to ileum?

Answer 30

Peyer's patches- MALT

Question 31

what are plicae circularis?

Answer 31

transverse fold in the small intestine with submucosal core, also called valves of Kerkring

Question 32

what are the intestinal villi?

Answer 32

mucosal outgrowths with a core of lamina propria

Question 33

what is another name for parietal cells?

Answer 33

oxyntic cells

Question 34

which type of cell in the fundic region is more superficial?

Answer 34

parietal is more superficial chief cells more basal enteroendocrine cells rest on basal lamina

Question 35

what is another term for "intestinal glands"? where are they found?

Answer 35

crypts of Lieberkuhn, found in lamina propria

Question 36

what is the typical appearance of enterocytes?

Answer 36

tall, columnar for absorption

Question 37

what is the "brush border"?

Answer 37

densely packed microvilli with actin filament cores

Question 38

what other type of cell is found adjacent to enterocytes? what do they produce?

Answer 38

goblet cells; mucin

Question 39

describe paneth cells

Answer 39

found in the basal aspect of the intestinal glands, contain granules that stain intense eosinophilic (red)

Question 40

what do paneth cell granules contain?

Answer 40

lysozyme- antibacterial | defensins- regulate T-cell activity

Question 41

what do the enteroendocrine cells of the small intestine secrete? (4)

Answer 41

``` glucoago-like peptide 1 GIP CCK secretin *all are hormones that control the secretion of other glands, local and blood-borne effects ```

Question 42

what are "M cells"?

Answer 42

cells that overly Peyer's patches, endocytose antigens and convey them to APCs below them

Question 43

where are Brunner's glands located? what is their action?

Answer 43

exclusively in the duodenum (submucosa), maintain optimal pH to protect against acid from the stomach and to maximize the actions of pancreatic enzymes

Question 44

what is the main structure of lacteal?

Answer 44

start in villi, form plexus at muscularis mucosa and within submucosa

Question 45

what are distinguishing features of jejunum?

Answer 45

well developed plicae circularis, rounded villi

Question 46

what are distinguishing features of ileum?

Answer 46

club-like villi, Peyer's Patches

Question 47

what is the appendix?

Answer 47

invagination of the cecum

Question 48

what are histologic cx of the appendix?

Answer 48

small diameter, abundant lymph tissue, no tenia coli

Question 49

what is tenia coli?

Answer 49

3 thickened muscularis externa, longitudinal mm bands on the outside of the colon

Question 50

how can the colon be differentiated from the small intestine?

Answer 50

colon lacks villi

Question 51

what is the epithelium of the colon?

Answer 51

tall, simple columnar

Question 52

where is the lymphoid tissue of the colon located?

Answer 52

lamina propria and submucosa

Question 53

what is the structure of the rectum?

Answer 53

similar to colon, but no tenia coli

Question 54

what occurs at the pectinate line?

Answer 54

delineation between tetum and anus with transition from simple columnar to stratified squamous non-keratinized epithelium

Question 55

what is the significance of the pectinate line to hemorrhoids?

Answer 55

above- internal | below- external

Question 56

does the colon contain crypts of lieburkuhn?

Answer 56

yes, but fewer than small intestine

Question 57

define adventitia

Answer 57

connects to another organ, more adipose cells, no mesothelium

Question 58

define serosa

Answer 58

has mesothelium, not continuous with other organs