Unit 2: GERD

Question 1

What are the three molecules that can stimulate parietal cells to secrete gastric acid?

Answer 1

Gastrin - binds to CCK2 receptors
Acetylcholine - binds to M3 receptors
Histamine - binds to H2 receptors

Question 2

What are the mechanisms of inhibiting acid secretion from the parietal cell?

Answer 2

Low pH stimulates D cells to produce somatastatin
This inhibits G cells from producing gastrin, gastrin can not act on parietal cells, neither can act on ECL cells to cause acid secretion.

Question 3

What is the mechanism behind acetylcholine and gastrin causing gastric acid secretion?

Answer 3

Activates phospholipase C
Formation of IP3
Cause an increase in calcium ions
Activates calmodulin kinase
Phosphorylation signalling cascade activates acid secretion

Question 4

What is the mechanism behind histamine causing acid secretion?

Answer 4

Activates adenylate cyclase
Increase levels of cAMP
Activates protein kinase A
Phosphorylation signalling cascade leads to activation of acid secretion

Question 5

What is the normal epithelial type found in the oesophagus?

Answer 5

Stratified sqaoumous epithelium

Question 6

What are the cellular mechanism by which H+ is transported into the stomach lining by parietal cells?

Answer 6

Water enters the pariteal cell from the blood by osmosis
Dissociates to give H+ ions
H+ ions are activly transported into the lumen by the proton pump in exchange for potassium ions
(K+ is recycled back into the lumen of the stomach down a concentratoin gradient)

Question 7

What are the cellular mechanisms by which Cl- is secreted out of parietal cells?

Answer 7

Chloride bicarbonate antiporter transports Cl- from the blood to the cytoplasm of the parietal cell.
Leaves the parietal cell to enter the lumen of the stomach by facilitated difussion thorugh chloride ion channels.

Question 8

What is the mechanism of action of lanzoprazole?

Answer 8

Is a proton pump inhibitor
Taken orally absorbed into the blood stream, is basic in nature so is attracted to the acidic environment surrounding the parietal cell.
In the acidic environment changes from a sulfoxide to a sulfenic acid
Forms a sulfide bond with a cystene amino acid in the proton pump
Conformational change in the proton pump inhibits H+ secretion
increases pH of the stomach

Question 9

When might lanzopraole be prescribed?

Answer 9

Treat GERD
Prevent peptic ulcers

Question 10

What are the common mechanism of action of over the counter indigestion tablets?

Answer 10

Antacids - bicarbonates neutralise the stomach acid
Sodium alginates - form a polysaccharide like mesh over the stomach contents, help to reduce reflux.

Question 11

How does acid reflux cause cell damage and throat scarring?

Answer 11

Ulcers - erodes through epithelium and mucosa
Repeated damage results in scar tissue as increased collagen content and cell numbers when heals.
Acid attacks and widens the tight junctions between cells
DAMPs and bradykinis release can cause chronic irritation and inflammation

Question 12

What are the consequences of peristent cell damage from acid reflux in GERD?

Answer 12

Develop Barrets Oesophagus
Histoligical changes from stratified sqaoumous to simple columnar - to better adapt to acidic environment
Oesophagus looses its pink squighy appearance, more hollow and dark red.
Dyspagia

Question 13

What are the rates of disease progression from GERD onwards?

Answer 13

5-15% of adults with GERD develop Barrets oesophagus
0.5% of Barrets oesophagus develop oesophageal cancer

Question 14

What are the symptoms of GERD?

Answer 14

heart burn like sensation
Sore throat
Belching and bloating
Pain and difficulty when swallowing
Chronic dry cough
Bad breath
Vomitting and nausea
In babies - poor feeding and weight gain

Question 15

How is GERD different to acid reflux?

Answer 15

GERD is persistent acid reflux from the stomach into the oesophagus throught he lower oesophageal sphincter
2-3 times a week

Question 16

What are the treatments for GERD?

Answer 16

Lifestyle modification - mainly diet orientated, alter sleep position, avoid tight clohting, reduce stress.
Encouraged to eat foods that are high in fibre and non-citrus e.g ginger
Medication - PPIs

Question 17

How do GPs perform throat examinations?

Answer 17

Observation from external - swelling, injury, bruising, ask about pain, ask to swallow or cough
Look inside the throat - changes in colour, collection of pus etc
Palpate the lymph nodes and outside of throat to identify any swelling or tenderness
Check ulva, cheeks, tongue, under the tongue, gums and tonsils

Question 18

What specialist diagnositic tools may be used in diagnosing GERD or Barrets oesophagus?

Answer 18

Endoscopy - camera on the end of tube down throat
- pH probe on the end of tube
mammometry - probe to measure pressure at the sphincter and contraction of muscles during peristalisis
Barium meal and x-ray to identify any structral abnormalities in the digestive tract.

Question 19

Why can BMI be less acurate in elderly people?

Answer 19

Lost muscle mass but gain fat mass

Question 20

What are some of the roles of professional chaperones in a GP surgery?

Answer 20

Translator
Witnesses to procedure - legal support for the GP
Carers to aid with mobility or communication

Question 21

What are the treatment options for Barrets oesophagus?

Answer 21

Endoscopic resection - endoscopy and removal of damaged cells by scraping from the surface
Radiofrequency ablation - radiowaves to removes damaged cells
Cryotherapy - repeated heating and freezing to remove damaged cells

Question 22

What are the risk factors for developing GERD?

Answer 22

Lifestyle - spicy foods, alcohol and smoking, obesity - increase pressure on the lower oesophageal sphincter
Genetic risk
Age - increased risk, peaks around 75 to 79yrs
Surgery or congenital condition causing faults in the lower oesophageal sphincter
Pregnancy - increased pressure on the lower oesophageal sphincter
Medications: NSAIDs, calcium ion blocjers,