L3 - Dyspepsia Flashcards
Location of myenteric plexus
between longitudinal and circular muscle
Location of submucousal plexus
lumenal side of circular muscle
Sympathetic fibres will terminate in…
- Meyenteric and submucousal plexus
- will inhibit ACH secretion.
Neuron’s within the myenteric and submucousal plexus constitute the enteric nervous system which involves what chemicals
- ACH
- Noradrenaline
- 5-Hydroxytrytamine (G-coupled receptor)
Chief cells release
Prorenin
Pepsingogen
Oxyntic cells (parietal cells) release
HCl
Intrinsic factor
Role of prostaglandins
e. g. PGE2 & I2
- cytoprotective role
- Increased bicarb secretion (act on EP1/2 receptor)
- Increase mucin secretion (EP4 receptor)
- Decrease H+ (EP2/3 on ECL)
- Prevents vasoconstriction, dilating BV
What is the process of acid output from parietal cell
- Cl- Actively transported into canaliculi in the cells which communicate with the lumen of the gastric gland.
- Accompanied by K+ secretion
- K+ exchanged for H+ within the cell via proton pump K+H+ATPase
- Carbonic anhydrase - carbonic acid - dissociation
- Bicarbonate exchanged from across basal membrane of parietal cell for Cl-
Gastrin binds to which receptors
CCK2 receptors on ECL.
ECL then releases histamine.
HIstamine binds to H2 receptor on parietal cell.
Parietal cell releases HCl
Gastrin produced?
- G cells in gastric antrum.
- Secreted into portal blood.
- Acts on gastrin / CCk receptors.
- Stimulates H+ secretion
- Stimulates histamine synthesis
ACH stimulates what receptor
- M3 receptor on parietal cells.
- Increases intracellular Ca2+
- stimulates H+ secretion.
- Inhibits somatostatin release from D-cells
Zollinger Ellison syndrome
Rare hypersecretory condition caused by gastrin producing tumour.
If untreated
- dysplasia of oesophagus epithelium which may progress to a pre-cancerous maybe dangerous Barret Oesophagus
How might NSAIDS contribute to GI problems?
May cause gastric bleeding, erosion.
- Inhibiting cyclooxygenase I which is key in the synthesis of protective prostaglandins.
Give an example of a cyclo-oxygenase II inhibitor causing less stomach damage
Celecoxib
Describe use and example of Histamine H2 receptor antagonists
- Inhibits histamine action at all H2 receptors
- Inhibits gastric acid secretion
Example
- Ranitidine
Use and example of PPI
- Peptic ulcer, reflux oesophagitis, ZE syndrome, part of therapy for H.Pylori
Example
- Omeprazole
- Lansoprazole
Antacids
Magnesium Trisilicate
Aluminium hydroxide
- used in dyspepsia