Gastric secretions

Question 1

What is a mucus neck cell?

Answer 1

stem cell compartment

Question 2

What to parietal cells produce?

Answer 2

HCL, Transcobalamine II, intrinsic factors

Question 3

what do ECL cells produce?

Answer 3

Histamines

Question 4

Where is the proton pump located in the gut? What drives it?

Answer 4

Apical membrane of parietal cells.
Driven by ATP
Electroneutral K passes the other way

Question 5

What are cells of the gastric pit?

Answer 5

Parietal cells located at base of gastric pits

Question 6

What happens when cells of the gastric pit are stimulated?

Answer 6

They insert H+-ATPase into the membrane

Question 7

What is the function of mucus cells?

What is the physical and chimerical barrier of mucus?

Answer 7

Mucus cells secrete mucus and bicarbonate to prevent the local low pH from damaging stomach lining

Physical-gel like
Chemical- biocarbonate

Question 8

What can disrupt the production of mucus?

Answer 8

Stress, chemicals, alcohol, NSAIDS

Question 9

Describe the feedback control of acid secretions when food is ingested

Answer 9

Distention of the stomach the the fundus causes parasympathetic stimulation of the parietal cells (vagus nerve, ACh) on M3 receptors which increases activity of the H+-K+ ATPase (proton pump) casuing secretions.
This innervation also stimulates Gastrin production which stimulates ECL cell to produce histamine which also stimulates H+- K+ ATPase in the parietal cells through H2 receptors (M3 mAChR)

Question 10

Which immune cell prduces histamine?

Which non immune cells secretes histamines?

Answer 10

Mast cells during allergic reactions

ECL cells

Question 11

Describe the feedback control of acid secretions - Which hormone inhibits acid secretions and how?

Answer 11

Somatostatin is released from from D cells in the mucosa. Somatostatin is a potent inhibitor of acid secretion; it inhibits gastrin secretion from G cells and histamine secretion from ECL cells.
Acts in a paracrine or endocrine (blood) manner

Question 12

what is Zollinger-Ellison syndrome?

Answer 12

Results in severe gastroesophageal peptic ulcer disease

Caused by gastric acid hyper secretions due to the ectopic secretion of gastrin by a neuroendocrine tumor (gastrinoma)

Question 13

Where is Zollinger-Ellison syndrome most likely to occur?

Answer 13

duodenum or pancreas

Question 14

Describe the cephalic phase of gastric secretions

Answer 14

Sight, smell, taste of food (cerebral cortex) stimulates the the Medullary nuclei
which stimulates the vagus nerve, which causes the secretion of HCL, mucus and pepsinogen.

Oral mechanoreceptors and chemoreceptors stimulate the medullary nuclei which stimulates the parasympathetic innervation of secretions

Question 15

Describe the Gastric phase of gastric secretions

Answer 15

Mechanical distension of
the stomach actiavtes stretch and chemoreceptors which trigger the submucosal and myenteric plexus to produce gut secretions, especially gastrine which increases HCL production.

Question 16

Which part of the brain does gastric distention secrete back to?

Answer 16

Medullary nuclei

Question 17

Describe the Intestinal phase of gastric secretions

Answer 17

During feeding, proteins in the chyme act to buffer the pH.
In an emptry stomach drops PH below 3. This causes the sympathetic inhibition of gastric secertions through acting on the medullary nuclei.

Also the activation of D cells to produce somatostatin to reduce production of gastrine

Question 18

Which hormones control bile secretions?

Answer 18

Cholecystokinin (CCK) (contracts gall bladder, sphincter of oddi relaxes)- production activated by fatty acids in duodenum
and
Secretin (stimulates biliary ductal cells)- acidic chyme stimulates secretin production

Question 19

What stimulates the production of Cholecystokinin (CCK)

Answer 19

Fatty acids in chyme

Question 20

What stimulates the production of Secretin

Answer 20

Acid in the chyme located in duodenum

Question 21

Where do Helicobacter pylori infections occur?

Answer 21

Duodenum and stomach

Question 22

what does Helicobacter pylori cause?

Answer 22

peptic ulcers (combined with stress, smoking,alcohol,NSAIDS)

Question 23

Describe the 4 stages of Helicobacter pylori infection

Answer 23

1. Tunnel through mucus layer
2. Secrete ammonia to neutralise
3. Recruit more H pylori
4. Mucosal damage

Question 24

How is Helicobacter pylori infection diagnosed?

Answer 24

1. Urea breath test: urea C14 is given to patient and H. Pylori converts urea C14 to ammonia (NH3) + C14O2
2. CLO test: biopsy placed in media with urea and pH indicator conversion of urea to ammonia raises pH ( if H. pylori present), which changes the colour of pH indicator.
3. Blood antibodies tests against H-pylori
4. Stool antigens test

Question 25

what is the treatment for H-pylori ?

Answer 25

2 antibiotics + 1 Proton pump inhibitor

Question 26

What are the treatment options for peptic ulcer disease?

Answer 26

Histamine (H2) antagonists- block H2 receptors on parietal cells to reduce acid secretion (famotideine) Proton pump inhibitors- (omeprazol) Prevent H+/K+ ATPase on parietal cell Reduce acid secretion Antibiotics- (Amoxycillin + Clarithomycin) Kill H Pylori bacteria Eradicate infection

Question 27

Which drugs make up the tripple treatment for H-pylori?

Answer 27

Amoxycillin + Clarithomycin+ omeprazol

Question 28

What is the common ending for protein pump inhibitors

Answer 28

prazol

Question 29

What is Gastroesophageal reflux disease?

Answer 29

When gastric contents flows back into oesophagus causing negative side effects

Question 30

What could possible cause Gastroesophageal reflux disease?

Answer 30

Weakened oesophageal epithelium Increased frequency Lower Oesophageal Sphincter Relaxation Hypersensitivity of oesophageal pain sensing nerves

Question 31

What are the treatment options for GORD and what do they effect?

Answer 31

``` Block M3 receptor with pirenzepine Block H2 receptor with H2RSs Activate prostoglandin receptor with misoprostol Inhibit H+/K+ pump with PPI's Neutralise acids (K+) with antacids ``` Fundoplication: standard surgical treatment for GORD. Tightens and reinforces the LOS. The upper part of the stomach is wrapped around the outside of the lower oesophagus to strengthen the sphincter

Question 32

What are the active ingrideints in gavison and how does it protect the stomach?

Answer 32

Active ingredients: Sodium alginate & Potassium hydrogen carbonate Formation of protective raft over acid pocket (Sodium alginate)

Question 33

Describe the surgical treatments for GORD

Answer 33

Fundoplication- Tightens and reinforces the LOS | The upper part of the stomach is wrapped around the lower oesophagus to strengthen the sphincter.

Question 34

Name the two types of Fundoplication

Answer 34

Laparoscopic Nissen fundoplication | LINX® magnetic anti-reflux device 

Question 35

What will you find in salivery secretions? What is the function of these components?

Answer 35

Amylase- Breaks down polysaccharides into disaccharides Lysozyme- Lyses (destroys) bacterial membranes Bicarbonate- Buffer, Neutralizes food and bacterial acids Growth factors- Signalling molecule which stimulates epithelial proliferation Transcobalamin II- Binds to vitamin B 12

Question 36

Describe the stages of B 12 absorption

Answer 36

Bind to Haptocorrin proteins produced in the salivary glands Must be complexed with stomach derived intrinsic pathway Absorbed in the terminal ileum Transported in portal circulation and transferred to transcobalamin II (TC-II/B12) Degraded in lysosome to allow function

Question 37

What do cheif cells produce?

Answer 37

Pepsinogen, chymosin, lipase

Question 38

What activates and inhibits ECL cells?

Answer 38

Gastrin activates ECL cell through CCK2 receptor, somatostatin inhibits ECL cell

Question 39

What percentage of the world has H-pylori infection?

Answer 39

over 50%