Stomach And Gastric Disease Flashcards
What are the three main functions of the stomach?
Storage facility,
Start digestion of protein, carbohydrates and fat,
Destroy pathogens in food
What are the three anatomical divisions of the stomach from superior to inferior?
Fundus,
Body,
Antrum
What aids the function of the lower oesophageal sphincter?
Right crus of the diaphragm constricts in high IAP
Acute angle of entry
Intrinsic smooth muscle
What change in epithelium is seen between the oesophagus and the stomach?
What is Barrett’s oesophagus?
Stratified squamous to simple columnar
Metaplasia of stratified squamous oesophageal tissue to columnar gastric mucosa
What is receptive relaxation?
Peristalsis causes reflex relaxation of the proximal stomach, distending the fundus and allowing the stomach to fill without a significant rise in pressure
What types of cells reside within the gastric pits?
Gastric gland cells
Parietal cells
Chief cells
G cells near antrum
What protective mechanisms does the stomach have?
Stomach mucosa secretes bicarbonate ions to buffer acidic conditions in local environment.
High turnover of epithelial cells.
Prostaglandins increase blood flow and support mucus layer
How do parietal cells secrete stomach acid?
- Carbonic anhydrase catalyses breakdown of carbonic acid into hydrogen ions and bicarbonate ions.
- Chloride ions anti ported into the cell against bicarbonate ions
- Hydrogen and chloride ions facillitated diffusion out of the cell and combine to form HCl
What is alkaline tide?
Bicarbonate ion secretion into venous blood causing a detectable increase in pH
What characterises the resting state of a parietal cell?
Tubulovesicles containing proton pumps remain separate from the apical membrane
What characterises the active state of a parietal cell?
Tubulovesicles containing proton pumps fused to cannaliculi of the apical membrane, allowing hydrogen ion secretion
What stimulates the production of stomach acid?
Senses - smell, sight, taste.
Stretch receptors in stomach,
Presence of amino acids or peptides,
Chyme sensed in duodenum
What stimulates a parietal cell?
Gastrin receptors (G cells) Histamine receptors (enterochromaffin cells) Muscarinic receptors (acetylcholine)
How is acid secretion inhibited?
D cells secrete somatostatin as a result of a sensed decrease in pH.
These bind to somatostatin receptors and inhibit secretion of gastrin
What is dyspepsia?
A complex of upper GI tract symptoms which are typically present for four or more weeks, including upper abdominal discomfort, nausea, heartburn, acid reflux and/or vomiting
What characterises Gastro-oesophageal reflux disease?
Heartburn
Acidic taste
Cough
(Sometimes asymptomatic)