Histology of the Stomach and Small Intestine

Question 1

WHat happens to the efpithelium as you go from the esophagus into the stomach?

Answer 1

switches from stratified squamous nonkeratinizing to simple columnar

Question 2

What’s the “sphincter” there?

Answer 2

the cardiac sphincter - there’s sphinctering action, but no swelling of the muscle

Question 3

What are the bumps on the inside of the stomach called?

Answer 3

rugae

Question 4

What are the areas on top of and between the rugae?

Answer 4

gastric areas - best apparent through a dissection microscope

Question 5

What layers extend up into the rugae and which dont?

Answer 5

the lamina propria, muscularis mucosae and submucosa extend up int he rugae, but the muscularis external does not

Question 6

What are the layers of the muscularis externa in the stomach?

Answer 6

inner oblique
middle circular
outer longitudinal

all smooth

Question 7

Which two muscle layers thicken to form the pyloric sphincter?

Answer 7

the inner oblique and middle circular

Question 8

Between what muscle layers does the myenteric nerve plexus lie?

Answer 8

between the middle circular and the outer longitudinal

Question 9

Does the stomach have a serosa or adventitia?

Answer 9

serosa

Question 10

What extends down into the mucosa in the stomach?

Answer 10

gastric pits

Question 11

Where do the glands terminate in the gastric lamina propria?

Answer 11

extend all the way to terminate adjacent to eh muscularis mucosa

Question 12

In the gastric pits, what eosinphilic cells are in the middle section of the walls?

Answer 12

the parietal cells

Question 13

In the gastric pits, what basophilic cells become more prevalent as you descend?

Answer 13

chief cells

Question 14

About how many glands empty into each gastric pit?

Answer 14

2-4

Question 15

What glands are located in the glandular region (upper region) of the pits?

Answer 15

gastric/fundic glands - just make mucus for protection

Question 16

What do we call the entrance to the gland itself?

Answer 16

the isthmus

Question 17

What’s the junction between the isthmus and the body of the gland?

Answer 17

the neck

Question 18

What types of cells are located in the neck?

Answer 18

mucous neck cells and parietal cells

note - this is also the most mitotic region

Question 19

What cells are located in the body of the pit?

Answer 19

this area is where most of the acid and enzymes of the stomach come from: parietal cells, chief cells, enteroendocrine cells

Question 20

What do parietal cells have a lot of besides mitochdonrai to help secrete acid?

Answer 20

secretory canaliculi

Question 21

How can you tell an enteroendocrine cell from other cells in the pits?

Answer 21

their secretory granules are on the basolateral side instead of the apical side - they secrete their products into the lamina propria or vascular system

Question 22

What cells produce secretin?

Answer 22

S cells in the small intestine

Question 23

What does secretin do?

Answer 23

stimualtes pancreatic and biliary bicarbonate and water secretion

Question 24

What cells produce CCK?

Answer 24

I cells in the small intestine

Question 25

What glands are located at the bottom of the gastric pits in the pyloric region?

Answer 25

pyloric glands - secrete mucus

Question 26

How else do the pits of the pyloric region differ from the body besides the lack of parietal and chief cells?

Answer 26

they get really long

Question 27

How do the gastric pits of the cardiac region differ?

Answer 27

they're short - only extend down about 1/4 of the mucosa thickness

Question 28

What are the glands of the cardiac region?

Answer 28

cardiac glands - basically mucous neck type

Question 29

Moving on to the small itnestine.... what are the prominent circular folds in the duodenum and upper jejunum. Not present in the ileum...

Answer 29

plicae circulares

Question 30

What are the histological features of the mucosa in the small intestine?

Answer 30

lots of villi with microvilli distinct muscularis mucosae plicae circulares

Question 31

What will extend up into the plicae circulares?

Answer 31

lamina propria, muscularis mucosae and submucosa make up the core

Question 32

How many layers are in the muscularis externa in the small intestine?

Answer 32

only two inner circular outer longitudinal

Question 33

Does the small intestine have an adventitia or a serosa?

Answer 33

serosa - except in the regions that are retroperitoneal (begining of duodenum)

Question 34

What three types of cells can be seen within the villus epithelium in the small intestine?

Answer 34

absorptive simple columnar cells GOBLET CELLS!!!! First time! Enteroendocrine cells

Question 35

What five cell types can be found in the crypt epithelium of the small intestine?

Answer 35

``` absorptive columnar cells goblet cells enteroendocrine cells paneth cells stem cells ```

Question 36

Where are paneth cells located? How do they stain?

Answer 36

They're located at the very base of the crypt and are strikingly eosinophlic.

Question 37

What do paneth cells do?

Answer 37

they have membrane bound granules with important antibacterial enzymes to control the microflora of the small intestine

Question 38

What does the lamina propria contain in the core of each villus?

Answer 38

a central lacteal, capillaries and venules also very cellular CT

Question 39

True or false: the muscularis mucosae does NOT extend into villi?

Answer 39

true don't get it mixed up with what goes up into plicae!

Question 40

What crypts open at the base of the villi?

Answer 40

crypts of lieberkuhn

Question 41

What lie at the tips fo the villi?

Answer 41

microvilli brush border

Question 42

What makes up the skeleton of the microvilli?

Answer 42

actin filaments that joint in a terminal web

Question 43

What's the tip off that you'r ein the duodenum?

Answer 43

brunner's glands

Question 44

What's the tip off that you're in the ileum?

Answer 44

peyer's patches

Question 45

What do brunner's glands secrete?

Answer 45

an alkaline mucous into the lumen of the duodenum to neutralize the acidic chyme arriving from the stomach

Question 46

What do peyer's patches do?

Answer 46

they are aggregates of lymphatic nodules that provide precursors of intestinal plasma cells for the production of secretory IgA

Question 47

What cells will endocytose antigen and transport it to the underlying lymphatic tissue?

Answer 47

M cells

Question 48

What happens to the number of goblet cells and you progress thorugh the GI tract?

Answer 48

they increase

Question 49

Where are peyer's patches normally located in relation to the mesentery?

Answer 49

opposite

Question 50

What affect do tight junctions have on membrane proteins?

Answer 50

they compartmentalize them - those on the basolateral side can't migrate up tot he apical