Gastric Secretion LAB

Question 1

what is the main diagnosis for H.pylori

Answer 1

C-urea breath test

Question 2

describe the sequence of events which occur to C-urea once it enters the patients stomach

Answer 2

normal carbon- 12
breath test- enriched Carbon 14

If H.pylori present in stomach, urease enzyme secreted which then reacts with C and causes CO2 and ammonia production.

enriched CO2 = H.pylori present
not enriched CO2 = H.pylori not present

Question 3

what are the other diagnosis techniques available

Answer 3

Blood test (serology for antibody IgG)
Stool test
Histological Biopsy
Endoscopy

Question 4

what are the contents of gastric juice

Answer 4

Hydrochloric acid
Pepsin
Mucin
Intrinsic factor

Question 5

what controls gastric acid secretion

Answer 5

Acetylcholine (neuronal – parasympathetic)
cephalic phase
Histamine (ECL cell – paracrine)

Gastrin (G cell – endocrine)
in response to high pH-gastric phase
Somatostatin (D cell – endocrine)
IN RESPONSE TO LOW pH – INTESTINAL PHASE

Question 6

Describe gastric secretion

Answer 6

ACh stimulates G cell to produce gastrin
ACh stimulates parietal cell to produce acid

Gastrin stimulates ECL cell to produce histamine
Gastrin stimulates parietal cell to produce acid

Somatostatin inhibits parietal cell acid secretion
Somatostatin inhibits ECL cell histamine secretion

Histamine stimulates acid secretion by acting on parietal cell via H2 receptor
Histamine stimulates acid secretion by acting on D cell via H3 receptor to inhibit somatostatin production

Question 7

list 3 physiological functions of gastric acid

Answer 7

Digestion (pepsinogen -> pepsin)
Absorption (Fe, Ca2+, viatmin B12)
Antimicrobial

Question 8

what is the pH of HCl in gastric acid

Answer 8

pH 0.8

Question 9

What protects gastric epithelium from damage by gastric acid

Answer 9

Mucous neck cells

produce mucous that protects the stomach from HCl

Question 10

describe Zollinger Ellison Syndrome

Answer 10

Disease in which tumors cause the stomach to produce too much acid, resulting in peptic ulcers.

Question 11

What is the main cause of peptic ulcer disease

Answer 11

H.Pylori

Question 12

What are the adverse effect of PPI

Answer 12

Reduction in Gastric Acid Output
- Reduced nutrient absorption (iron, calcium and vit B12)
- Reduced gastric antimicrobial function (risk of enteric infections)
Increase in serum gastrin Levels (osteoporosis)

Question 13

what normally prevents gastric acid from refluxing into oesophagus

Answer 13

lower oesophageal sphincter

Question 14

what is the normal resting pressure of the LOS and how do u measure that

Answer 14

2-3 mmHg

manometry

Question 15

what lifestyle factors may produce GORD and what is the mechanism of the effect

Answer 15

increased BMI, obesity
pregnancy
–> increased pressure on stomach so weakens the LOS muscles

smoking
alcohol
coffee/chocolate
stress
--> may relax LOS muscles

Question 16

what drugs can be used for management of GORD and how do they work

Answer 16

1) Histamine 2- receptor antagonist (e.g. Zantac)
competitively inhibits the H2 receptor on the parietal cell -> inhibiting acid secretion
2) PPIs- weak bases (e.g. Lansoprazole)
Acts on the final common pathway- irreversibly binds to and blocks the proton pump  inhibiting acid secretion from the parietal cells

Question 17

What is the role of surgery in the management of reflux disease

Answer 17

Vagotomy: (surgery uncommon nowadays)
This was the treatment before drugs were introduced
involves cutting the vagus nerve. Thus, ennervating the stomach-> no peristalsis so food is emptied very slowly after the surgery.
High risk of gastric cancer after surgery

Question 18

what is the treatment for peptic ulcers

Answer 18

• triple therapy involving proton pump inhibitors and two of the three antibiotics (Amoxycillin, Clarithromycin and Metronidazole).

The triple therapy is taken for a week.