2A A&P of the stomach

Question 1

What are the four main regions of the stomach?

Answer 1

Cardia, fundus, body, and pylorus (CFBP - can’t find blood pressure)

Question 2

What are the two sphincters of the stomach?

Answer 2

LES and pyloric

Question 3

What hangs off the greater curvature of the stomach?

Answer 3

Greater omentum (visceral peritoneum)

Question 4

What are the three layers of the muscularis mucosa?

Answer 4

Longitudinal (outer), circular(middle), oblique(innermost)

Question 5

How does the muscularis layer in the stomach differ from most of the GI tract?

Answer 5

Has a third layer (innermost) of muscle fibers running oblique. Most of the GI tract only has two layers - longitudinal and circular

Question 6

What is the most important protection of the gastric mucosa from gastric acids and enzymes?

Answer 6

A layer of alkaline mucus - gastric mucosal barrier

Question 7

What role do prostaglandins play in the stomach?

Answer 7

Protect the stomach mucosa from injury by enhancing alkaline mucus production

Question 8

What does the alkaline mucus contain a lot of?

Answer 8

Bicarbonate

Question 9

What is the pH at the cell surface of stomach mucosa cells? Stomach pH?

Answer 9

Close to neutral.

pH of 2

Question 10

How long to cells at the surface of the stomach live?

Answer 10

3-4 days

Question 11

What kind of epithelium makes up the mucosal surface of the stomach?

Answer 11

Simple columnar epithelium

Question 12

What is the stomach epithelium dotted with?

Answer 12

Millions of deep channels called gastric pits

Question 13

what are gastric pits lined with?

Answer 13

Columns of specialized cells called gastric glands

Question 14

Where do gastric glands reside?

Answer 14

Within the gastric pits

Question 15

What cells line the gastric pits?

Answer 15

Surface lining cells, regenerative cells, mucous neck cells, Parietal cells, Chief cells, and Enteroendocrine cells

Question 16

Which cells in the gastric pit produce the most alkaline mucus?

Answer 16

Mucous neck cells

Question 17

What do parietal cells produce?

Answer 17

HCL and intrinsic factor

Question 18

What cells secrete pepsinogen and gastric lipase?

Answer 18

Chief cells

Question 19

What do enteroendocrine cells secrete?

Answer 19

Gastrin (G cells) and histamine (ECL cells)

Question 20

What part of the stomach are parietal cells found in greatest number? Chief cells? G cells?

Answer 20

Upper, middle, lower - PCG

Question 21

What are the functions of the stomach?

Answer 21

Temporary storage, mechanical digestion, chemical digestion, and secretion of gastrin and histamine

Question 22

What is chyme?

Answer 22

A creamy, soupy paste created in the stomach from mechanical digestion of food

Question 23

What do gastric parietal cells produce from CO2 and water?

Answer 23

H2CO3, which dissociates into H+ and bicarbonate

Question 24

How does Cl- get into the parietal cell?

Answer 24

Via chloride shift when bicarbonate leaves the cell into the blood, there is the famous chloride shift that occurs!

Question 25

What is the cephalic phase?

Answer 25

Vagus nerve weakly stimulates gastric juice secretion when food is being chewed in the mouth, or with the sight, smell or thought of food. Vagus nerves stimulates gastrin secretion, which stimulates secretion of gastric juice

Question 26

When does the gastric phase begin?

Answer 26

When food reaches the stomach

Question 27

What stimulates more gastrin secretion?

Answer 27

Distension of stomach and protein digestion products (amino acids) via positive feedback loop. Vagus nerve also continues to stimulate gastrin release and gastric motility

Question 28

What do elevated levels of gastrin stimulate?

Answer 28

The release of histamine, which in turn increases HCl secretion from parietal cells

Question 29

Are there enzymes in the stomach to digest carbs?

Answer 29

No, no chemical digestion of carbs happens in the stomach

Question 30

What activates pepsinogen into pepsin?

Answer 30

HCl

Question 31

What does pepsin do?

Answer 31

Breaks down peptide bonds of amino acid chains

Question 32

Can pepsin breakdown all peptide bonds?

Answer 32

No, only certain peptide bond

Question 33

What is the end result of what pepsin can do?

Answer 33

Partially digest proteins

Question 34

In what phase is pepsin very active?

Answer 34

Gastric phase

Question 35

Small amounts of chyme enter the duodenum and stimulate the secretion of what three hormones?

Answer 35

CCK, secretin, and GIP

Question 36

What do the CCK, secretin, and GIP enzymes do?

Answer 36

Inhibit gastric juice secretion

Question 37

What does GIP inhibit in addition to gastric juice secretion?

Answer 37

Gastric motility

Question 38

In what phase are the three ezymes - CCK, secretin, and GIP - produced in the duodenum?

Answer 38

Intestinal phase

Question 39

Why is the control of chyme leaving the stomach and entering the duodenum critical?

Answer 39

1) so duodenum does not become too full (w/ acid) | 2) so small intestine can adequately process the incoming chyme

Question 40

What increases gastric motility?

Answer 40

Gastrin and vagus nerve activity

Question 41

During what phase does the pyloric sphincter relax?

Answer 41

Gastric phase

Question 42

What is the enterogastric reflex?

Answer 42

products of protein digestion and H+ in the duodenum inhibit vagus nerve activity (occurs during the intestinal phase)

Question 43

What can the stomach mechanically digest? Chemically digest?

Answer 43

All nutrients - carbs, proteins, and lipids. | Varies - quite a bit of protein, a little bit of lipids, and not much at all of carbs