GIT Flashcards
Stimulus, mechanical and chemical properties of digestion
Stimulus: Acid and Enzymes are released
Mechanical: Churning or crushing of food
Chemical:
- Stomach acid to breakdown food particles and protect against food pathogens
- Enzyme such as pepsin breaks-down ingested protein into amino acids
covers upper abdominal pain, fullness, early satiety, bloating and nausea. It can occur with gastric and duodenal ulceration
Dyspepsia
is associated with heartburn, acid regurgitation and sometime difficulty in swallowing.
Gastro-oesophageal reflux disease
chemicals associated with stomach acid secretion
Histamine (chemical mediator of allergic reactions such as airway obstruction) via H2 receptors
Acetylcholine (neurotransmitter responsible for autonomic response) via M3 receptors
Gastrin (peptide hormone responsible for enhancing gastric mucosal growth and motility in the stomach) via CCK1 receptors
medications that inhibits the gateways of acid secretions
proton pump inhibitors
proton pump inhibitors meds
omeprazole
pantoprazole
lanzoprazole
MoA of PPIs or proton pump inhibitors
irreversibly inhibit the H+K+ ATPase or hydrogen potassium ATPase pump (an enzyme that acidifies the stomach) causing the reduction of acid production.
PPIs adverse effects
risk of GI infection
vitamin B12 (responsible for making new RBCs) deficiency leading to pernicious anaemia
diarrhoea
headache
CAN CAUSE REBOUND GASTRITIS (since receptors were up-regulated enabling them to stimulate acids even more due to prolonged inhibition) is stopped after a long treatment
Meds only blocks H2 receptors. prevents stimulation of acid secretion caused by histamine via H2 receptors
Histamine H2 receptor antagonists
H2 receptor antagonist meds
Famotidine
H2 receptor antagonist adverse effects
diarrhoea
headaches
rashes
medication that does not work as proton pump inhibitor however, works with actual present acids in the stomach lumen neutralising it by releasing alkaline salts to buffer pH in the stomach. Usually prevents heartburn
Antacids
Antacids meds
Alginates such as Gaviscon
Aluminium
Magnesium
Calcium carbonate
Antacids adverse effects
Aluminium - constipation
Magnesium - diarrhoea
as food moves through the colon, the ________ absorbs water from the food while it forms _____________. Muscle contraction in the colon then push the stool toward the _____________. Stool is solid by the time it reaches the rectum as most water was absorbed.
colon
stool
rectum
occurs when the colon absorbs too much water, muscle contractions in the colon are too slow or sluggish which causes the stool to move slowly resulting to become dry and hard.
Constipation
Common cause of constipation
dehydration
low fibre diet
immobility (weakened abdominal walls)
neurological disorders
refusal to open bowels
most susceptible to vulnerable groups such as disabled, older adults and pregnant women
medications that causes constipation
opioids
Anticholinergics - TCAs, clozapine
Diuretics
Iron
complications of constipation
haemorrhoids
anal fissures
bowel obstruction
rectal prolapse
Bulk laxatives MoA
create bulk through addition of non-absorbable matter to faecal contents
it requires large intake of water since minimal osmotic action
Meds - psyllium
adv effects - decrease appetite
faecal softeners MoA
acts as a surface detergent allowing fat and water to enter and soften the stool
meds - sodium docustate, poloxamer, sodium citrate (rectal)
osmotic laxatives MoA
osmotic gradient for movement of water into the small or large intestines
increases bulk and soften faecal mass
promotes peristalsis (stretching of digestive tract)
meds - lactulose, magnesium, glycerol (rectal)
adv effects - abdominal cramps and flatulence
stimulant laxatives MoA
direct stimulant of myenteric plexus (responsible for peristalsis of bowel movement)
increases peristalsis
meds - senna, bisacodyl (rectal)
adv effects - stomach cramps, dependency when long-term use
occurs from overstimulation of muscle and nerves where there is less reabsorption of water in the body causing too much water in the stool
diarrhoea
diarrhoea treatment
REHYDRATE
anti-motility agents - opioid agonists (loperamide and codeine phosphate)
antidiahhroeal (loperamide) pharmacodynamics
binds to GI receptors to inhibit the release of acetylcholine via MU receptor > decrease peristalsis and increase transit time
