Upper GI Disorders: Mouth + Oesophagus Flashcards
What is the GI tract made up of?
Mouth
Oesophagus
Stomach
Pancreas
Small intestine
Large intestine
Liver
What are the main GI disorders?
Gastro oesophageal reflux disease (GORD)
Peptic ulcer disease (PUD)
What is an oral ulceration?
Break in oral epithelium
What is oral ulceration caused by?
Physical or chemical injury
Drugs
What is stomatitis?
Inflammation of lining of any of soft-tissues of mouth
What is stomatitis caused by?
Poor oral hygiene
Poorly fitted dentures
What is leukoplakia?
Painless white patches on side of tongue/cheek
What is oesophagus made up of?
Upper oesophageal sphincter
Oesophageal body
Lower oesophageal sphincter
Diaphragm
What does the UOS prevent?
Air entering oesophagus + reflux
What does LOS prevent?
Reflux
What is GORD?
Exposure of unprotected oesophageal epithelium to acid
What is the stomach made up of?
Fundus
Body
Pylorus
What is present at body of stomach?
Parietal cells (HCl)
Mucous cells
Chief cells
What is present at pylorus of stomach?
Mucous cells
G cells
D cells
NO ACID SECRETING CELLS
What is aspirin used for?
Pain killer
Blood thinner
Describe how parietal cells secrete acid
Resting cell H+/K+-ATPase in cytoplasmic vesicles
Stimulated cell H+/K+-ATPase membrane fused
Increase SA + membrane pumps
What are the positive regulators of parietal cell?
(Stimulate to release acid)
Acetylcholine
Histamine
Gastrin
What is the negative regulator of parietal cell?
Somatostatin
Describe acetylcholine positive regulator
Enteric neurons released from
Direct parietal cell stimulation
Describe histamine positive regulator
ECL cells
Direct parietal cell stimulation
Paracrine activity
Describe gastrin positive regulator
G cells
Endocrine action
Stimulate histamine release
Directly stimulates parietal cell proliferation
Describe somatostatin negative regulator
D cells
Directly inhibits parietal cell secretion
Inhibits gastrin + histamine release
What is the Ach receptor in acid secretion pathway?
Muscarinic M3 receptor
What is the histamine receptor in acid secretion pathway?
H2
What is gastrin receptor in acid secretion pathway?
CKKB/CCK2 receptor
What does Ach + gastrin act through in acid secretion pathway?
G-coupled receptors
Increase Ca2+ + diacylglycerol
Through PLC-inositol 1,4,5-triphosphate (IP3) pathway
What does histamine act through in acid secretion pathway?
G-coupled receptors
Increase cAMP
What gastrin + Ach dependent on?
Ca2+
What is histamine dependent on?
cAMP
What are the 3 stages of acid secretion stimulation?
Cephalic phase
Gastric phase
Intestinal phase
Describe cephalic phase
1
Sight/smell/ thought food
Describe gastric phase
2
Food in stomach
Mechanoreceptor neural reflex
Peptides in food stimulate G cells = gastrin
Food increase pH = prevent D cell activity
Describe intestinal phase
3
Chyme enter duodenum
Feedback prevent chyme acidity
Duodenal stimulation of hormones
Decrease food, decrease pH = stimulates D cell activity
What happens to gastric secretion following food?
Food in stomach buffers acid + raises pH
Suppresses D cells
Gastrin + HCl released
Stomach distention, digestion triggers secretion vol + HCl
Food leaves stomach = acid increases = pH falls
= D cells stimulated = somatostatin inhibits HCl production
How is HCl secretion controlled?
Direct stimulation of ECL
Direct stimulation of G cells
Inhibition of somatostatin
Pyloric antrum exposure to peptides
Describe the mechanism of HCl secretion
CO2 diffuses into parietal cell
Hydrated to carbonic acid by carbonic hydrase
H2CO3 dissociated to H+ + H2CO3-
H+/K+-ATPase actively transport H+ out, K+ in
Na+ actively reabsorbed
K+ recycles to gastric lumen via K+ channel
Cl- exits passively from cells via Cl- channel
What are the protective functions of prostaglandin acid regulation?
Increase mucus secretion
Increase cell regeneration
Increase HCO3- release
Increase H+ secretion
Increase blood flow
What is present to protect against acid?
Intrinsic mucosal protection
