Digestive System: Stomach

Question 1

What are the functions of the stomach?

Answer 1

Continue digestion of carbs
Storage (*primary function)
Some nutrient breakdown (mostly chemical, less physical)

Question 2

What are the gross anatomical features of the stomach?

Answer 2

Concave lesser curvature
Convex greater curvature
Cardia: narrow region by gastroesophageal sphincter
Fundus: domed region filled with gas
Body/corpus: largest portion
Pylorus: constricted portion by pyloric sphincter
Rugae: longitudinal folds which allow for distention
Gastric pits: tiny depressions in stomach’s surface, 1 pit leads to more than one gland

Question 3

What is the surface epithelium of the mucosa of the stomach?

Answer 3

Simple columnar

Question 4

What are the functions of the surface mucosa cells of the stomach?

Answer 4

Produce thick visible mucus

Secrete bicarbonate ions (buffering)

Question 5

Where are the regenerative cells found in the stomach?

Answer 5

Bases of pits

Question 6

What makes up the lamina propria of the stomach?

Answer 6

Loose vascular CT present in small amounts between glands

Question 7

What makes up the muscularis mucosae of the stomach?

Answer 7

Smooth muscle layers that is often arranged in three layers

Question 8

What are the three layers of the stomach’s muscularis mucosae?

Answer 8

1. Inner circular
2. Outer longitudinal
3. Outermost circular/oblique

Question 9

Is the submucosa of the stomach vascular?

Answer 9

Yes, it is highly vascular

Question 10

Where is the submucosa of the stomach located?

Answer 10

AVA (arteriovenous anastomosis)

Question 11

What is the function of the AVA?

Answer 11

To shut down activity and secretion FAST

Question 12

What is next to the inner circular layer of muscle in the stomach submucosa?

Answer 12

Submucosal (Meissner’s) plexus

Question 13

What is the function of the submucosal plexus in the stomach?

Answer 13

To influence the mucosa through secretion, blood flow, and any limited muscle contractions

Question 14

How many layers of muscularis externa are possible in the stomach? Where at?

Answer 14

3 layers; especially between the cardiac region and greater curvature (all smooth muscle)

Question 15

What are the layers of the stomach’s muscularis externa?

Answer 15

1. Innermost oblique
2. Middle circular (well developed)
3. Outer longitudinal (thin)

Question 16

Where is the myenteric (Auerbach’s) plexus located in the stomach?

Answer 16

Between circular and longitudinal layers

Question 17

What is the function of the myenteric plexus in the stomach?

Answer 17

To stimulate muscularis externa

Question 18

Which is present in the stomach: serosa or adventitia?

Answer 18

Serosa

Question 19

What three regions of the stomach is gastric histology based off of?

Answer 19

Cardiac, Gastric (fundus and body), Pyloric

Question 20

Why do the cardiac glands have a coiled base in the cardiac region?

Answer 20

Due to shorter pits

Question 21

What cells are present in the cardiac region of the stomach?

Answer 21

Primarily surface mucous, some neck mucous, a few DNES and parietal cells. NO chief cells

Question 22

Which region of the stomach is the smallest and obtains much mucus?

Answer 22

Cardiac region

Question 23

What are the boundaries of the gastric glands of the gastric region?

Answer 23

Extends from gastric pit to muscularis mucosae

Question 24

What is another name for the gastric gland?

Answer 24

Zymogenic gland

Question 25

What are the three regions in the gastric gland?

Answer 25

Isthmus, Neck, Base

Question 26

How long do the surface mucous cells in the isthmus live?

Answer 26

3-5 days

Question 27

What do the surface mucous cells of the isthmus produce?

Answer 27

Thick visible mucus that traps bicarbonate ions

Question 28

What is the function of the surface mucous cells of the isthmus?

Answer 28

To protect mucosa from auto-digestion and the rougher components of chyme

Question 29

What is another name for the DNES cells in the isthmus?

Answer 29

Enteroendocrine cells

Question 30

What are types of DNES cells in the isthmus?

Answer 30

Type D, Type EC, Type G

Question 31

What do the Type D DNES cells do?

Answer 31

Produce somatostatin which inhibits release of hormones/HCL by nearby DNES cells

Question 32

What do the Type EC DNES cells do?

Answer 32

Produce serotonin and substance P which increases gut motility

Question 33

What do the Type G DNES cells do?

Answer 33

Produce gastrin which stimulates HCL and pepsinogen secretion, aids in gut motility, acts as regenerative cells in body of stomach

Question 34

How long do the mucous cells of the neck live?

Answer 34

6 days

Question 35

What do the neck mucous cells produce?

Answer 35

A soluble, less alkaline mucus

Question 36

What is the function of the neck mucous cells?

Answer 36

To lubricate gastric contents

Question 37

Do the regenerative cells of the neck replace all cell types?

Answer 37

Yes

Question 38

How long do the parietal (oxyntic) cells of the neck live?

Answer 38

150-200 days

Question 39

What makes up the neck parietal cells?

Answer 39

Odd columnar with intracellular canaliculi

Question 40

Do the parietal neck cells produce acid?

Answer 40

Yes, very strong HCL with a pH of 0.8 and buffered immediately to 1.2 pH

Question 41

What do the parietal neck cells produce?

Answer 41

Very strong HCL | Gastric intrinsic factor

Question 42

What is the function of the parietal neck cells?

Answer 42

Necessary for vitamin B12 absorption

Question 43

What can chronic gastritis lead to?

Answer 43

Pernicious anemia

Question 44

Low number of which cells can lead to low amounts of intrinsic factor?

Answer 44

Parietal cells

Question 45

Low amounts of intrinsic factor causes what?

Answer 45

Decreases vitamin B12 absorption which is necessary for RBC maturation

Question 46

Are there a lot of DNES cells present in the neck?

Answer 46

No, there are few

Question 47

Where are the chief cells located? What is their other name?

Answer 47

Located in the base of the gastric region; also known as Zymogenic cells

Question 48

How long do the chief cells live?

Answer 48

60-90 days

Question 49

What do the chief cells produce?

Answer 49

Primarily pepsinogen and some gastric lipase

Question 50

What is the purpose of pepsinogen? Gastric lipase?

Answer 50

Pepsinogen- break down proteins | Gastric lipase: break down fats

Question 51

Are parietal cells present in the base?

Answer 51

Yes, some are

Question 52

How long do the DNES cells of the base live? Are there many or few?

Answer 52

60-90 days, few are present

Question 53

What types of cells are present in the isthmus of the gastric region?

Answer 53

``` Surface mucous cells DNES cells (Types D/EC/G) ```

Question 54

What types of cells are present in the neck of the gastric region?

Answer 54

Neck mucous cells Regenerative cells Parietal (oxyntic) cells DNES cells

Question 55

What types of cells are present in the base of the gastric region?

Answer 55

Chief (zymogenic) cells Parietal cells DNES cells

Question 56

How are the pits in the pyloric region of the stomach?

Answer 56

Deeper; very twisted and branched pyloric glands (shorter glands)

Question 57

What types of cells are present in the pyloric region?

Answer 57

Surface mucus (primarily) DNES cells Parietal cells Neck mucous cells

Question 58

What do some of the neck mucous cells of the pyloric region produce?

Answer 58

Lysozyme

Question 59

What is the pyloric sphincter?

Answer 59

The anatomical sphincter between the pylorus of the stomach and the duodenum

Question 60

What are characteristics of an anatomical sphincter?

Answer 60

Well developed inner circular layer of muscle in muscularis externa Inner circular layer in muscular externa can be independently controlled