stomach - physiology + disease

Question 1

what is the function of the stomach (4)

Answer 1

stores/churns food
continues the digestion of carbohydrates
initiates digestion of protein
regulates the delivery of chyme

Question 2

name the main anatomical regions of the stomach

Answer 2

lower oesophagus sphincter 
fundus
body
antrum
greater and lesser curve
pylorus/pyloric sphincter

Question 3

what are the two sphincters associated with the stomach

Answer 3

lower oesophagus sphincter (LOS)

pyloric sphincter

Question 4

what are the two types of glands within the stomach

Answer 4

PGA = pyloric gland area
OM = oxyntic mucosa

Question 5

what is the location of the pyloric gland area

Answer 5

antrum

Question 6

what is the location of the oxyntic mucosa

Answer 6

body and fundus

Question 7

what cells are found in the oxyntic mucosa

Answer 7

D cells and G cells

Question 8

what cells are found in the pyloric gland area

Answer 8

parietal cells, chief cells, and entrochromaffin-like cells

Question 9

what is produced in the oxyntic mucosa

Answer 9

HCL
pepsinogen
intrinsic factor & gastroferrin
histamine

Question 10

what is produced in the pyloric gland area

Answer 10

somatostatin

gastrin

Question 11

what does gastrin do

Answer 11

stimulates HCL secretion

Question 12

where is gastrin produced and by what cells

Answer 12

G cells in the pyloric gland area

Question 13

what does somatostatin do

Answer 13

inhibits HCL secretion

Question 14

where is gastrin produced and by what cells

Answer 14

D cells in the pyloric gland area

Question 15

what does HCL do

Answer 15

activates pepsinogen to pepsin

denatures proteins

Question 16

where is HCL produced and by what cells

Answer 16

parietal cells in the oxyntic mucosa

Question 17

what does pepsinogen do

Answer 17

inactivate precursor to pepsin

Question 18

where is pepsinogen produced and by what cells

Answer 18

chief cell in the oxyntic mucosa

Question 19

what does histamine do

Answer 19

stimulates secretion of HCL

Question 20

where is histamine produced and by what cells

Answer 20

entrochromaffin-like cells in the oxyntic mucosa

Question 21

what does in the intrinsic factor and gastroferrin

Answer 21

binds to B12 to allow absorption in terminal ileum

Question 22

where are intrinsic factor and gastroferrin produced and by what cells

Answer 22

parietal cell in the oxyntic mucosa

Question 23

what does parietal cells produce

Answer 23

HCL

intrinsic factor and gastroferrin

Question 24

what does chief cells produce

Answer 24

pepsinogen

Question 25

what does entrochromaffin-like cells produce

Answer 25

histamine

Question 26

what does D cells produce

Answer 26

somatostatin

Question 27

what does G cells produce

Answer 27

gastrin

Question 28

what determines the passage of chyme

Answer 28

the strength of the astral wave

Question 29

what are the 3 phases of gastric acid secretion

Answer 29

cephalic phase gastric phase intestinal phase

Question 30

when does the cephalic phase take place

Answer 30

before food reaches the stomach, prepares it to receive food

Question 31

how is the cephalic phase driven

Answer 31

directly and indirectly by the CNS and vagus nerve (CNX)

Question 32

when does the gastric phase take place

Answer 32

when food is in the stomach

Question 33

when does the intestinal phase take place

Answer 33

after food has left the stomach

Question 34

what stimulates the intestinal phase

Answer 34

chyme entering the upper small intestine via neuronal and hormonal mechanisms (WEAK stimulation)

Question 35

how is are gastric secretions in the cephalic phase inhibited

Answer 35

vagal nerve activity decreased upon cessation of eating and following stomach emptying (pain, nausea and negative emotions also decrease vagal activity)

Question 36

how are the gastric secretions in the intestinal phase inhibited

Answer 36

via the same methods that reduce gastric motility

Question 37

how are the gastric secretions in the gastric phase inhibited

Answer 37

antral pH falls when food leaves the stomach causing somastostain release from D cells

Question 38

how is the mucosa protected from HCL and pepsin

Answer 38

located produced prostaglandins: PGE2 and PGI2

Question 39

what do prostaglandins PGE2 and PGI2 do

Answer 39

reduce acid secretion increase mucus and bicarb secretion increase mucosal blood flow

Question 40

what causes acute gastritis

Answer 40

``` ⇒ irritant chemical injury ⇒ Severe burns ⇒ Shock ⇒ Severe trauma ⇒ Head Injury ```

Question 41

what are the 3 causes of chronic gastritis

Answer 41

autoimmune (rare) bacterial/H.pylori (most common) chemical

Question 42

what is the cause of autoimmune chronic gastritis

Answer 42

anti-parietal and anti-intrinsic factor antibodies

Question 43

what is the main symptom of autoimmune gastritis

Answer 43

pernicious anaemia

Question 44

what causes pernicious anaemia

Answer 44

B12 deficiency

Question 45

what causes chemical chronic gastritis

Answer 45

NSAIDs alcohol bile reflux

Question 46

describe what happens in chemical chronic gastritis

Answer 46

direct injury to mucus layer by fat solvents leading to marked epithelial regeneration, hyperplasia, congestion and little inflammation