GI pharmacology Flashcards
what do PPIs do
irreversible inhibition by covalent modification of the gastric gland, parietal cell H+/K+ atp ase
where is the h+/K+ ATPase present
on the apical canalicular membrane
what is the H+/K+ atpase
the final pathway by which gastrin, ach and histamine increase gastric acid production, therefore blocking the h/k ATPase is more effective than h2 antagonists which is a competitive antagonist of H2 receptor and only blocks the action of histamine
when are PPIs used
in the treatment of GU, DU and GORD
what are some of the side effect to PPIs
are thought to increase the risk of clostridium difficile if used for long term, may disguise gastric cancer, diarrhoea, headache, abdo pain ,nausea and fatigue
what does the PPI interact with that can affect the absorption of other drugs
P450
what does interaction with P450 do
decrease platelet activity of clopidogrel
increase the effect of phenytoin and warfarin
describe the 4 parts to the structure of the internal alimentary canal
most inner layer is the muscosa which is made up of epithelium, lamina propria, a thin layer of looseconnective tissue and the muscularis mucosa-thin layer of smooth muscle
submucosa-loose connective tissue
muscularis externa-circular muscle then longitudinal muscle
serosa or adventitia-outer layer of connective tissue
what structures are found in the stomach
gastric pits and at the bottom of the gastric pit are 1-7 gastric glands
what is contained within the isthmus of the gastric pit
mostly parietal cells
what mutation is present in the HNPCC gene
mutation in DNA mismatch repair gene
what cells are present in the neck of the gastric pit
mucous and stem
what cells are present in the base of the gastric pit
mostly chief a few parietal and neuroendocrine cells
where are parietal cells found
in the isthmus of the gastric pit
where are mucous and stem cells found
neck
where are chief cells a few parietal and neuroendocrine cells found
base of the gastric pit
what layer is increased to form the pyloric sphincter
the inner circular layer is increased to form the pyloric sphincter
what does the cardia have
deep gastric pits, that branch into loosely packed tortuous glands
what does the body of the stomach have
shallow pits
what does the pylorus have
deep gastric pits with branched coiled gastric glands at a higher density than in the cardia
what des the small intestine contain
crypts of lieberkuhn
what does the duodenum contain and what is so unique about their location
brunners glands in the submucosa, this is unusual as it is the only part of the GI tract with glands in the submucosa
where are the plicae circularis located
in the mucosa and submucosa
what is located in the mucosa and submucosa of the jejunum
plicae circularis
what is contained within the ileum and where
lymphoid follicles called payers patches in the submucosa and often extending into the lamina propria
what are enterocytes made of
tall columnar epithelium cells with a brush border
what do goblet cells produce and what does this cause
goblet cells produce mucin and this protects the epithelium and lubricates the passagage of material
what are the two types of cell in the large intestine
absorptive cells which remove salts and thereby water and goblet cells which serete mucus to lubricate the colon
describe some features of the appendix
a blind ending hollow extension of the caecum
less crypts than in the colon
circular arrangement of lymphoid tissue in submucosa and often lamina propria
lymphoid tissue declines with age
what is there between the rectum and anal canal
a distinct junction between the mucosa of the rectum and stratified squamous epithelium of anal canal
2-3 cm long canal is then continuous with stratified squamous epithelium of the surrounging skin
where is auerbachs myenteric plexus
in between the longitudinal and circular muscle layer
where is meissners submucosal plexus
in the submucosa
name the 2 parts of the ENS
auerbachs myenteric plexus and meissners submucosal plexus
what si the first line investiagation for biliary colic
ultrasound
what is the first line investigation for diverticulitis
CT
what is the first line investigation for pancreatitis
ultrasouns to exclue gallstones or biliary obstruction and then CT to evaluate complications eg necrosis
what is first line investigation for appendicitis
ultrasound
what is the first line investigation for a distended abdomen
depends what you think the cause is
fluid-ultra sound
bowel source-AXR
what si the first line investigation for a distended abdomen thought to be caused by bowel
AXR
first line investigation for distended abdomen caused by fluid
ultrasound
if suspect perforation what investigation do you do
erect CXR
what is the first line investigation for jaundice
ultrasound
if a post hepatic cause of jaundice was identified on ultrasound what would be the next investigation
ERCP/MRCP
if an intrahepatic cause of jaundice was found on ultrasound what investigation would you do next
CT
if cirrhosis was seen on ultrasound what investigation would you do next
Biopsy (guided by ultrasound)
when are fluoroscopic contrast studies used
if small bowel disease is suspected with strictures wall thickening, fistulation
how does plummer vinson present
patient being investigated for anaemia and then complains of dysphagia
what can long term oesophageal reflux cause that is benign
a stricture
