GI

Question 1

What cells in the stomach produce HCl (gastric acid)?

Answer 1

Parietal cells

Question 2

What else do parietal cells produce?

Answer 2

Intrinsic factor

Question 3

What is the function of intrinsic factor?

Answer 3

Absorption of vitamin B12

Question 4

What cells in the stomach produce pepsinogen?

Answer 4

Chief cells

Question 5

What is the active form of pesinogen?

Answer 5

Pepsin

Question 6

What is the role of pepsin?

Answer 6

The breakdown of proteins - specifically collagen, thus helps the breakdown of meat

Question 7

What protects the stomach from acid?

Answer 7

Mucus

Question 8

What produces the mucus?

Answer 8

Mucus secreting neck cells

Question 9

Which parts of the stomach have full gastric glands - contain all the cells

Answer 9

Body and fundus - the cardiac and pyloric regions are devoid of parietal and chief cells

Question 10

What is the epithelial lining of the stomach?

Answer 10

Simple columnar epithelium

Question 11

What are the deep invaginations of the surface epithelium called?

Answer 11

Gastric pits

Question 12

How many layers of muscle are present in the stomach?

Answer 12

3

Question 13

Is the muscle in the stomach smooth or skeletal?

Answer 13

Smooth

Question 14

What does the muscularis mucosa have in addition to two layers of smooth muscle?

Answer 14

Elastic tissue - this helps cause the stomach to collapse on emptying

Question 15

Whereabouts in the gastric glands are the parietal cells located?

Answer 15

Predominently in the upper part, near the gastric pits

Question 16

What shape are the parietal cells?

Answer 16

Globular

Question 17

What enzyme are the parietal cells rich in?

Answer 17

Carbonic anhydrase

Question 18

What is the average pH for the stomach?

Answer 18

2

Question 19

What shape are chief cells?

Answer 19

Pyramidal

Question 20

Whereabouts in the gastric glands are the chief cells located?

Answer 20

In the deeper part of the gland

Question 21

What else, in addition to pepsinogen, do the chief cells produce?

Answer 21

Lipases

Question 22

What is the difference between the gastric glands in the cardiac and pyloric regions compared to the body and fundus?

Answer 22

Those in the cardiac and fundus regions are:

1) Shorter
2) Coiled (rather than straight)
3) Composed mainly of mucous neck cells (similar to those in the glands of the body and fundus)

Question 23

What cells are also found in the stomach in addition to the parietal, chief and mucous cells?

Answer 23

Enteroendocrine cells

Question 24

What are the two phases that turn on gastric secretion?

Answer 24

1) Cephalic

2) Gastric

Question 25

What are the two phases that turn off gastric acid secretion?

Answer 25

1) Gastric | 2) Intestinal

Question 26

What happens in the cephalic phase to turn on gastric acid secretion?

Answer 26

1) PNS activated by sight, smell, taste and chewing 2) PNS releases acetylcholine 3) Acetylcholine increases gastrin secretion and histamine secretion 4) These increase gastric acid secretion from the parietal cells

Question 27

What happens in the gastric phase to turn on gastric acid secretion?

Answer 27

1) Gastric distention occurs and peptides and amino acids arrive in stomach 2) This increases gastrin secretion 3) gastrin secretion acts directly on parietal cells and increases histamine secretion 4) Overall increase in gastric acid secretion occurs

Question 28

What happens in the gastric phase to turn off gastric acid secretion?

Answer 28

1) Luminal pH falls 2) Gastric acid secretion is inhibited 3) Histamine secretion is therefore inhibited 4) Somatostatin secretion is stimulated 5) Parietal cells activity is inhibited and gastric acid secretions are reduced

Question 29

What factors are involved in the intestinal phase?

Answer 29

1) Duodenal distention 2) Low luminal pH 3) Hypertonic luminal contents 4) Presence of amino and fatty acids

Question 30

What is released in the intestinal phase in response to the factors in the duodenum?

Answer 30

Entergasterones

Question 31

What are the two enterogaterones?

Answer 31

1) Secretin | 2) Cholecystokinin (CCK)

Question 32

What is the role of secretin?

Answer 32

It inhibits gastrin release and promotes somatostatin release

Question 33

What is the role of CCK?

Answer 33

It is the major hormone responsible for gallbladder contraction and pancreatic enzyme secretion

Question 34

Proteins are involved in the gastric turning on phase, how does the mechanism work?

Answer 34

The proteins act directly on gastrin release but also act as buffers removing the H+ ions and thus increasing pH. The increase in pH therefore decreases somatostatin release which thus leads to lack of inhibition of the parietal cells

Question 35

What are the three types of solution that can occur inside the body in terms of solute concentration?

Answer 35

1) Isotonic 2) Hypotonic 3) Hypertonic

Question 36

What is meant by isotonic?

Answer 36

Where the concentration of the solute is the same both inside and outside the cell

Question 37

What is meant by hypotonic?

Answer 37

Where the concentration of the solute is greater inside the cell

Question 38

What is meant by hypertonic?

Answer 38

Where the concentration of the solute is greater outside the cell

Question 39

What is the parasympathetic neurotransmitter involved in gastric acid regulation? Does it increase or decrease production?

Answer 39

Acetylcholine - it increases production

Question 40

What is the hormone involved in gastric acid regulation? Does it increase

Answer 40

Gastrin - it increases it

Question 41

Whta are the two paracrine factors involved in gastric acid regulation? Do they increase or decrease the production?

Answer 41

1) Histamine - increase | 2) Somatostatin - decrease

Question 42

What are the three defence mechanisms in the mucosa of the stomach?

Answer 42

1) Alkaline mucus 2) Tight junctions between epithelial cells 3) Replacement of damaged mucosa cells

Question 43

What are the three main causes of peptic ulcers?

Answer 43

1) Helicobacter pyori 2) NSAIDs 3) Chemical irritants

Question 44

How does helicobacter pylori cause peptic ulcers?

Answer 44

1) Releases urease 2) Urease splits into CO2 and ammonia 3) Ammonia combines with H+ to form ammonium which damages the gastric epithelium

Question 45

How do NSAIDs cause peptic ulcers?

Answer 45

NSAIDs inhibit cyclo-oxygenase 1 which is needed for prostaglandin secretion. Prostaglandins are needed to stimulate mucus secretion thus there is decreased mucus

Question 46

What is a gastrinoma?

Answer 46

A tumour of the pancreas or duodenum that secretes excess gastrin

Question 47

What major structures pass through the diaphragm?

Answer 47

1) Inferior vena cava 2) Oesophagus 3) Aorta

Question 48

At what level does the Inferior vena cava pass through the thoracic diaphragm?

Answer 48

T8

Question 49

At what level does the oesophagus pass though the thoracic diaphragm?

Answer 49

T10

Question 50

At what level does the aorta pass through the thoracic diaphragm?

Answer 50

T12