Gastric Secretion

Question 1

What is the function of the fundus?

Answer 1

Storage

Question 2

What it the function of the body?

Answer 2

Storage

Mucus, HCl, Pepsinogen (Prevents autodigestion) & Intrinsic factor secretion

Question 3

What is the function of the antrum?

Answer 3

Mixing/Grinding & Gastric secretion

Question 4

Is the Muscularis externa thicker in the fundus or the antrum?

Answer 4

Antrum

Question 5

What do Mucous neck cells secrete?

Answer 5

Mucus

Question 6

What do Chief cells secrete?

Answer 6

Pepsinogens

Question 7

What do Parietal cells secrete?

Answer 7

HCl & Intrinsic factor

Question 8

What does Gastric Acid (HCl) do?

Answer 8

Activates digestive enzymes

Denatures proteins

Question 9

How are hydrogen ions removed from the cell?

Answer 9

They are coupled in a 1:1 ratio with Potassium entering the cell
ATP heavy

Question 10

How do Chlorine ions enter the cell?

Answer 10

They are coupled in a 1:1 ratio with bicarbonate (HCO3) leaving the cell
ATP driven process

Question 11

What does bicarbonate do?

Answer 11

Neutralizes acid

Question 12

How is pepsin formed?

Answer 12

Pepsinogen becomes pepsin via the action of Hydrogen ions in the stomach lumen

Question 13

What does gastrin and acetylcholine act through to increase protein kinases?

Answer 13

Its own receptor and then Calcium

Question 14

What do histamines bind to, to increase protein kinases?

Answer 14

Its own receptor Gs

Then through cyclic AMP (cAMP)

Question 15

What are protein kinases required for?

Answer 15

To stimulate the Potassium/Hydrogen pump

Question 16

What do prostaglandins do?

Answer 16

Shut off Adenolyne Cyclane - It is inhibitory

Question 17

What are the three ways in which gastric acid is secreted?

Answer 17

Neurocrine - Vagus/Local reflexes
Endocrine - Gastrin
Paracrine - Histamine

Question 18

What are the two phases of stomach stimulation?

Answer 18

Gastric phase

Cephalic phase

Question 19

Describe the cephalic phase?

Answer 19

Sight/Smell of food innervates the vagus nerve causing an increase in ACh & Gastrin resulting in the parietal cells secreting acid
Histamines released from ECL cells which are innervated by Gastrin/ACh

Question 20

Describe the gastric phase?

Answer 20

Same as cephalic phase stomach distention causes vagal stimulation and peptides in lumen stimulate G cells

Question 21

What inhibits the cephalic phase?

Answer 21

Stopping eating

Decreasing vagal acitivity

Question 22

What inhibits the gastric phase?

Answer 22

Decrease in pH levels

Increased in HCl levels

Question 23

What is the enterogastric reflex?

Answer 23

The sympathetic reflex which reduces Gastrin secretion and thus acid secretion

Question 24

What are enterogastrones?

Answer 24

Hormones released from gland cells in the duodenal mucosa

Question 25

What hormones are released in the duodenal mucosa?

Answer 25

Secretin Cholecystokinin GIP

Question 26

What are enterogastrones released in response to?

Answer 26

Acid Hypertonic solutions Monoglycerides Fatty acids

Question 27

What do enterogastrones do?

Answer 27

Prevent further acid build up in the duodenum

Question 28

What two strategies do enterogastrones have?

Answer 28

Inhibit gastric acid secretion | Prevent gastric emptying

Question 29

What cell secretes pepsinogen (Zymogen = Inactive precursor)?

Answer 29

Chief cells

Question 30

What do Zymogens do?

Answer 30

Their storage prevents cellular digestion

Question 31

At what pH are pepsins inactivated?

Answer 31

Neutral

Question 32

At what pH is pepsinogen converted to pepsin?

Answer 32

Less than 3

Question 33

Where is intrinsic factor produced?

Answer 33

Parietal cells

Question 34

What is the main function of intrinsic factor?

Answer 34

Vitamin B12 absorption

Question 35

Where is the intrinsic factor/B12 complex absorbed?

Answer 35

Ileum

Question 36

Where is gastric mucus produced?

Answer 36

Surface epithelial cells and mucous neck cells

Question 37

What are the functions of gastric mucus?

Answer 37

Protects the mucosal surface from mechanical injury | Creates a neutral pH to protect against gastric acid corrosion and pepsin digestion