alimentary immune functions Flashcards
immunological disorders: identify the symptoms, mechanisms, diagnosis and treatment/management associated with cholera infection, Crohn's disease, coeliac disease, irritable bowel syndrome, ulcerative colitis and infectious diarrhoea
3 symptoms of irritable bowel syndrome
recurrent abdominal pain, abnormal bowel motility, constipation/diarrhoea
how is irritable bowel syndrome (functional disorder) different to inflammatory bowel disease
inflammatory bowel disease also contains inflammation, ulcers and other damage
what type of abdominal pain is experienced in irritable bowel syndrome
visceral hypersensitivity
what is visceral hypersensitivity
sensory nerve endings in intestinal wall have abnormally strong response to stimuli (e.g. stetching after meal)
why do sufferers of irritable bowel syndrome have abnormal bowel motility
unabsorbed short-chain carbohydrates (lactose, fructose) act as solutes, drawing water into lumen, triggering visceral hypersensitivity and causing smooth muscles to spasm, creating diarrhoea if excess water not reabsorbed
how else might spasms or pain be caused in irritable bowel syndrome
unabsorbed short-chain carbohydrates metabolised by gastrointestinal bacterial flora, creating gas which causes spasms or pain
2 risk factors of irritable bowel syndrome
having had gastroenteritis (norovirus, rotavirus), stress
4 treatments of irritable bowel syndrome
diet modification, constipation, spasms and pain, management of stress, anxiety, depression
how is diet modified in irritable bowel syndrome
avoid certain foods with short-chain carbohydrates e.g. apples, beans, cauliflowers
how is constipation treated in irritable bowel syndrome
soluble fiber, stool softeners, osmotic laxatives
how are spasms and pain treated in irritable bowel syndrome
anti-diarrhoeals (serotonin antagonists), anti-muscarinic
3 symptoms of coeliac disease
abdominal distension (bloating), diarrhoea, sometimes dermititis herpetiformis
in coeliac disease, what is not broken down in the stomach
gliadin (33 amino acid peptide component of gluten)
fate of gliadin in coeliac disease
reaches small intestine and binds to secretory IgA in mucosal membrane
fate of gliadin-secretory IgA complex
binds to transferrin receptor (TFR) and transferred to lamina propria
what cuts of the amide group from the protein
enzyme tissue transglutaminase (tTG)
fate of deamidated gliadin
phagocytosed by macrophages and presented by MHC class II, causing destruction of epithelial cells due to activation of immune system
2 methods of diagnosis of coeliac disease
antibody blood tests (anti-gliadin, anti-tTG, anti-endomysial (EMAs)); biopsy test of duodenum
2 methods of dietary management of coeliac disease
gluten-free diet (wheat, barley, rye exclusion), medication
what are factors affecting compliance in coeliac disease
lifestyle, eating out, cross contamination
2 symptoms of Crohn’s disease
pain in affected area (normally right lower quadrant); diarrhoea and blood in stool
what pathogens trigger Crohn’s disease
mycobacterium paratuberculosis, pseudomonas, listeria
what does unregulated immune response in Crohn’s disease cause
destruction of cells in GIT
what are responsible for development of Crohn’s disease
gene mutations e.g. frame-shift mutations in NOD2 gene
what medications can be used to treat Crohn’s disease
anti-inflammatory drugs, antibiotics
what medication can be prescribed in severe Crohn’s disease
immunosuppressants e.g. corticosteroids
if other medical therapies are contraindicated, or surgery is used (remove tissue but not curing disease), what is recommended in Crohn’s disease
liquid diet (nutritionally complete liquid feeds) along with corticosteroids
what needs to be considered if using a liquid diet to treat Crohn’s disease
type of feed, route, compliance, monitoring, assessment, refeeding syndrome risk
progression from liquid diet in Crohn’s disease
liquid diet to low fibre/low residue, then food reintroduction
how to manage strictures in Crohn’s disease to decrease obstruction, pain and gas production
change diet so that food can get through the stricture; as fibre can block the intestines, avoid fibrous parts of fruit and vegetables (skins, seeds, woody stalks), wholegrains, nuts, seeds, gristle and skin from meat and fish
what can food intolerance test result in in Crohn’s disease
food exclusion and nutritionally inadequate diets, as no evidence for intolerance
2 symptoms of ulcerative colitis
pain in left lower quarant (due to ulcers along inner surface of large intestine); severe and frequent diarrhoea, sometimes with blood in stool
mechanism of ulcerative colitis
autoimmune disorder whereby T cells destroy cells lining walls of large intestine
secondary cause of ulcerative colitis
diet and stress
what anti-inflammatory drugs are used to treat ulcerative colitis
sulfasalazine, mesalamine
immunosuppressant drugs prescribed if ulcerative colitis is severe
corticosteroids, azathioprine, cyclosporine
what can cure ulcerative colitis
colectomy (surgical removal of colon)
what is used to minimise exacerbation of diarrhoea in ulcerative colitis
dietary manipulation
why are pre/probiotics used in ulcerative colitis
treat and prevent pouchitis (when colon removed, leaving a pouch that becomes inflamed); help remission
what may prebiotics cause in ulcerative colitis
abdominal pain, bloating, diarrhoea, flatulence
dietary manipulation involved in treating diarrhoea in ulcerative colitis
drink fluid, nutritious drinks, replace salt; consume soluble fibre to help gut absorb more water from stool; avoid gas producing foods, high fibre or wholegrain cereals, alcohol (which worsens dehydration), caffeine and personal triggers
3 symptoms of cholera infection
vomiting, nausea; abdominal pain; severe dehydration and diarrhoea (watery)
how is Vibrio cholerae transmitted
through foecal-oral route through contaminated water and food
mechanism of cholera getting into body if unvaccinated
bacteria reaches small intestine from stomach, where flagellum propels it towards epithelial cell; on making close contact it releases cholera toxin
what does cholera toxin do in epithelial cell
starts a series of biochemical reactions resulting in exit of ions such as Na+, K+, Cl- and water
diagnosis of cholera infection
stool test, to detect bacteria or antigen for the bacteria
main treatment for cholera infection
drink lots of clean fluids and eat clean flood
treatment for severe cholera infection
IV fluids, antibiotics
