week 6 Flashcards
where are parietal cells absent from?
the antrum
what controls saliva secretion?
reflexes mediated by the ANS
What causes increase in watery saliva, rich in amylase and mucous.
parasympathetic nervous system
What causes increase in thicker mucous and reduction in saliva glands?
Sympathetic nervous system
What is logD a measure of?
lipophilicity in all states
Agonists that stimulate acid secretion
Histamine, gastrin, acetylcholine.
Histamine receptor antagonist
Racecadotril
Dyspepsia symptoms
upper abdominal pain/discomfort, heartburn, gastric reflux, nausea, vomiting.
Peptic ulcers; what are they, where are they found?
sores that develop in the lining of the stomach, lower oesophagus or small intestine (duodenum). Duodenum ulcers are most common
What is peritonitis?
When peptic ulcers perforate, and bacteria that live in the stomach are able to escape and infect the lining of the abdomen. Can rapidly spread to sepsis, symptoms including sudden sudden, intense steady abdominal pain.
__ ulcer pain is classically aggravated by meals whereas, __ ulcer is relived.
gastric, duodenal
Factors that protect the walls of the stomach from being digested - Alkaline mucus
1- Alkaline mucus ; mucosa surface lined with secretory cells that release alkaline mucus that forms a thin layer over the luminal surface. Protein content of mucus and its alkaline nature, neutralize H+ in the immediate area of the epithelium. Mucus forms a chemical barrier between the highly acidic contents of the lumen and the cell surface.
Factors that protect the walls of the stomach from being digested - tight junctions between epithelial cells
these tight junctions between the epithelial cells lining of the stomach limit the diffusion of H+ into the underlying tissues.
Factors that protect the walls of the stomach from being digested - replacement of damaged cells every few days
damaged epithelial cells are replaced every few days by new cells arising by the division of cells within gastric pits.
Describe ulcer formation.
involves breaking down the mucosal barrier and exposing the underlying tissue to the corrosive action of acid and pepsin.
Factors affecting acid and pepsin levels, therefore increased chance of peptic ulcer disease.
smoking, genetic factors, stress and helicobacter pylori.
How do NSAIDs increase risk of peptic ulcer disease?
can impair mucosal defence and therefore also increase peptic ulcer formation. They allow back diffusion of hydrogen ions
Duodenal ulceration associated with
excess acid secretion
Gastric ulceration associated with
breakdown of the protective function of the gastric mucosa
H.Pylori stimulates increased __ release thereby increased acid secretion.
gastrin
How does H.Pylori act?
It causes inflammation of the gastric mucosa and infects the lower part of the stomach. It uses chemotaxis to avoid areas of low pH, and also neutralizes the acid in the environment by producing large amounts of urease, which breaks down the urea present in the stomach to carbon dioxide and ammonia. This ammonia neutralizes stomach acid.
How can H.Pylori be tested for?
urea breath test, stool antigen test to detect antigens in an active infection
What is secreted in the stomach body?
mucus pepsinogen and HCl
What is secreted in the antrum?
mucus pepsinogen and gastrin
Treatment of peptic ulcer disease
Antacids, Antisecretory agents (Histamine receptor H2 antagonists, Proton pump inhibitors), Eradication of H.Pylori infection.
Antacids
neutralise free acids in the stomach and stimulate mucosal repair around ulcers. Symptomatic relief
Antisecretory agents - Histamine receptor H2 antagonists examples and their side effects
cimetidine, nizatidine, famotidine, ranitidine reduce acid secretion.
diarrhoea, headache, confusion in the elderly, gynaecomastia with cimetidine. Potential interactions between cimetidine and warfarin, phenytoin and theophylline
Proton Pump Inhibitors examples and method of action.
omeprazole, lansoprazole, pantoprazole, esomeprazole.
Inhibition of the pump almost completely blocks acid secretion, irreversible. Acid secretion is inhibited by around 90% for around 24 hours with a single dose.
When are PPIs most effective? Why is this?
More effective when taken at meals times as they only bind to active pumps.