gastrointestinal_week_2_20190518174132 Flashcards
what is jaundice (icterus)
yellowing of sclera (white of eyes) and skin
what causes jaundice
increase in blood levels of bilirubin
what is bilirubin
normal by-product of breakdown of RBC which occurs in spleen and is used to form bile in liver
what is the role of biliary tree
connects liver to 2nd part duodenum
what is the role of gallbladder
storage and concentration of bile
what is role of bile
normal absorption of fats from small intestine
what is role of pancreas
excretes digestive enzymes into 2nd part of duodenum - necessary for digestion of food
what is functions of liver (largest organ)
glycogen storage, bile secretion and other metabolic functions
what is the surface anatomy of the liver
mainly in RUQ, protected by ribs 7-11 and location changes in breathing
where is gallbladder in relation to liver
posterior and inferior
where is hepatic flexure in relation to liver
inferior
where is right kidney, right adrenal gland, IVC and abdominal aorta in relation to liver
posterior
where is stomach in relation to liver
posterior at mid/left side
what are the 4 anatomical lobes of liver
right lobe and left lobe (seen anterior)quadrate lobe and caudate lobe (seen posteriorly)
there are 8 functional segments which allow for segmentectomy. What does each segment contain
branch of hepatic artery, branch of hepatic portal vein, bile drainage (to bile duct) and venous drainage (to IVC)
IVC and hepatic veins lack valves - what is the consequence of this
increase in central venous pressure is directed to liver
what happens to the hepatic veins directing deoxygenated blood from liver before entering IVC
come together as 3 veins
what is contents of the portal triad
hepatic portal veinhepatic artery properbile duct
the structures of the portal triad run within which ligament
heptaduodenal
what is the coeliac trunk
first of 3 midline branches of aorta - leaves aorta at T12 and supples organs of foregut
the coeliac trunk trifurcates into 3 branches - what are these
splenic artery, left gastric artery and common hepatic artery
when does common hepatic artery become hepatic artery proper
when it gives off the gastroduodenal artery
where does the splenic artery run
superior to border of pancreas
where is spleen located
it is an intraperitoneal organ within left hypochondrium
what is the spleen anatomically related to
posteriorly to diaphragm anteriorly to stomachinferiorly to splenic flexuremedially to left kidney
what ribs protect spleen
9-11
what is the major blood supply to stomach
right and left gastric arteries and right and left gastro-omental arteries
where do right and left gastric arteries run
along junction of lesser curvature and lesser omentum - anastomose together
where do right and left gastro-omental arteries run
along junction of greater curvature and greater omentum - anastomose together
where does majority of blood received by liver come from
hepatic portal vein
where is the rest of blood supply to liver from
right and left hepatic arteries and branches of hepatic proper
what are the 2 clinically important areas of peritoneal cavity related to liver
hepatorenal recess (morisons pounch) and sub-phrenic processboth within greater sac
what can peritonitis result in in relational to these areas
collection of pus in recesses leading to abscess formation
which recess is one of lowest parts of cavity when patient supine and thus pus will drain if patient bedridden
hepatorenal recess
what is the role of hepatic portal vein (HPV)
drains blood from foregut, midgut and hindgut to liver for first pass metabolism
what forms the HPV
splenic vein (drains foregut) and superior mensenteric vein (drains midgut)
how does the HPV drain blood from hindgut then
because inferior mensenteric vein drains blood from hindgut to splenic vein
what is the role of interior vena cava in relation to HPV
drains cleaned blood from hepatic vein into right atrium
what structures are within portal triad
bile ducthepatic artery proper hepatic portal vein
where does the gallbladder lie
on the posterior aspect of liver and anterior to duodenum
what is function of gallbladder
stores and concentrates bile in between meals
bile flows in and out of gallbladder via what
cystic duct
what is three sections of gallbladder
neck (at cystic duct), body and fundus
what is the blood supply to gallbladder
cystic artery - branch of right hepatic artery an located in cystohepatic triangle (of calot)
what is the consequence of a gallstone
inflammation of gallbladder or cystic duct
gallblader is foregut - where does visceral afferents enter spinal cord and where is pain felt
T6-T9pain felt in epigastric region
where is can gallbladder pain present
hypochrondrium (top left and right)with or without pain referral to right shoulder as result of anterior diaphragmatic irritation
what is cholecystectomy
surgical removal of gall bladder
the common hepatic duct (combination of right and left hepatic) unites with cystic duct to form what
bile duct (common bile duct)
what is the 4 parts of duodenum
superior (duodenal cap - intraperitoneal), descending, horizontal and ascending
what is pyloric sphincter (where flow of chyme begins)
controls flow of chyme from stomach to duodenum
where does flow of chyme end
duodenojejunal flexure
what peptide hormones does duodenum secrete into blood
gastrin, CCK
where is pain from duodenal ulcer felt
epigastric region
where is pancreas located
retroperitoneal organ that lies transversely across te posterior abdomen
what is 4 parts of pancreas
head (with uncinate process), neck, body, tail
what lies posteriorly to pancreas
right kidney and adrenal gland, IVC, bile duct, abdominal aorta, superior mesenteric vessels, left kidney and adrenal gland, part of portal venous system
what lies anterior to pancreas
stomach
what lies superoposteriorly to pancreas
splenic vessels
what is exocrine function of pancreas
acinar cell (pancreatic digestive enzymes into main pancreatic duct)
what is endocrine function of pancreas
islets of langerhans (insulin and glucagon into bloodstream)
how does the biliary system drain
bile duct descends posteriorly to 1st part of duodenum, travels into groove onto posterior aspect of pancreasthen joints with main pancreatic duct forming ampulla of vaterboth then drain into 2nd part of duodenum
what smooth muscle sphincters are present in biliary system
bile duct sphincter pancreatic duct sphincter sphincter of Oddi
what is ERCP (endoscopic retrograde cholangiopancreatography)
investigation used to study biliary tree and pancreas and treat some pathologies associated with it
what are 2 main causes of jaundice
gall stones carcinoma at head of pancreas
how does this cause jaundice
flow of bile back up to the liver results in overspill into the blood of its constituents (including bilirubin)
what is one of the reasons for pain arising from pancreas
secondary to inflammation - pancreatitis
what is one cause of pancreatitis
blockage of ampulla by gallstone - bile is then diverted into pancreas leading to irritation and inflammationin more advanced cases, vascular haemorrhage can occur leading to blood/fluid accumulation in retroperitoneal space
where is pancreatic pain felt
foregut and midgut organ - presents in epigastric region and/or umbilical region can also radiate to back
where is grey-turners sign (in pancreatitis)
right or left flanks
where is cullens sign (in pancreatitis)
around umbilicus via falciform ligament
where are parts of small intestine located
1st and 2nd part of duodenum are foregut organs the rest of SI are midgut organs
where is jejunum and ileum found (make up most of SI)
all 4 quadrants jejunum begins at duodenaljejunal flexureileum ends at ileocaecal junction
what is colour difference between jejunum and ileum
jejunum is deep red, ileum is lighter pink
what is wall difference
jejunum is thicker and heavy, ileum thinner and lighter
what is vascularity difference
jejunum more vascular, ileum less vascular
what is difference in mesenteric fat
jejunum has less, ileum has more
what is difference in circular folds (L, plicae circularis)
jejunum has large, tall and closely packed fold ileum has low and sparse folds (absent distally)
what is different in lymphoid tissue (peyers patches)
present in ileum
what is arterial blood supply of jejunum and ileum
superior mesenteric arteries via jejunal and ileal arteries
what is course of superior mesenteric vessels
leaves aorta at L1 vertebral level, posterior to neck of pancreastravels inferiorly, anterior to uncinate process of pancreas to enter the mesentery proper
how is fat absorbed
bile absorbs fats from GI tract lumen into intestinal cellsfats (within chylomicrons) then absorbed from intestinal cells into specialised lymphatic vessels of SI called lactealsthey travel via lymphatic system to eventually drain into venous system at left venous angle
what are the main groups of lymph nodes draining abdominal organs
celiac (forgut organs)superior mesenteric (midgut organs)inferior mesenteric (hindgut organs)lumbar (kidneys, posterior abdo wall, pelvis and lower limbs)
what are peyers patches
distinctive structures within specialised epithelial lining, containing B and T lymphocytes and antigen presenting cells
where are peyers patches most numerous
terminal ileum
which specialised epithelial cells do peyers patches contain
M cells - lack microvilli and contain membranous folds enclosing lymphocytes, macrophages and dendritic cells these trap antigens and transport them across epithelium to interact with immune cells
what is the function of M cells
transport intact peptides, viruses and bacteria across epithelium and pass them on to antigen-processing and antigen-presenting cells
what mediates homing to the mucosa
cell surface molecules that interact with receptors on blood vessels in GI tract
what molecule does lymphocytes homing to the intestine express
a4B7 which interacts with MAD-CAM (mucosal addressin cell adhesion molecule)
what is an example of specific cytokines (chemokines) attracting subsets of lymphocytes to different parts of intestine
thymus and epithelial expressed chemokine (TECK) attracts cells to intestine via surface receptor CCR9
what is the most abundant immunoglobulin in bronchial, reproductive tract and intestinal secretions
IgA
how is secretory dimeric immunoglobulin A (sIgA) created and released
two IgA, joined to form polymeric IgA, binds to receptor called secretory component (SC) on basolateral surfaces of epitheliaThe complex is transported across cytoplasm and sIgA is released at luminal surface by proteolytic cleavage of SC
which prions, viruses and pathogenic bacteria (respectively) are taken up by M cells allowing spread of infection
bovine spongiform encephalopathy (BSE) agentHIVShigella
selective IgA deficiency affects how many people, without much effect on enteric immunity
1 in 500
which diseases cause chronic immune stimulation which can lead to excess proliferation of immune cells, neoplastic change and intestinal lymphoma
helicobacter pylori or coeliac disease
what occurs when IgA binds to poly-Ig receptors
endocytosis
what is the role of poly-Ig receptors
allows IgA replacement by IgM as it recognises any polymers
death caused by T cells causes flattened epithelial cell in coeliacs - what is consequence of this
decreased absorption -malabsorption is key symptom
what happens when mucosal immunity becomes dysregulated
infected dendritic cells shuttle virus from the site of exposure to the regional lymph nodes where they concentrate virus particles and infect CD4+ T cells
what is selective IgA deficiency
2/3 asymptomatic remainder recurrent sinopulmonary infections (coeliac disease 10x)
what is CVID
failure to differentiate into Ig secreting cellsrecurrent sinopulmonary and GI infections
what is XLA
no B cellssinopulmonary and GI infections plus devastating systemic manifestations
what is CGD
failure of phagocyte respiratory burststaphylococcus aureus/inflammatory granulomas
what is SCID
profound defect in T and B cell immunity oral candidiasis, chronic diarrhoea, interstitial pneumonitis
how is a food allergy caused
type 1 hypersensitivity reaction initiated by crosslinking of allergen specific IgE on surface of mast cells with specific allergen
how is coeliac disease diagnosed
biopsy serology useful as screening test
what is crohns disease
focal and discontinous inflammation with deep and eroding fissures +/- granulomas commonly affects distal ileum and colon
what is the immunology of crohns disease
mediated by Th1 CD4+ T cells / gamma interferon / IL-12 / TNF alpha
what is ulcerative colitis
restricted to rectum and colon -distortion of crypts with infiltration of monocytes / neutrophils and plasma cells
what is the cause of ischaemia of small bowel
mesenteric arterial occlusion (atheroscleorisis or thromboembolism from heart)non occlusive perfusion insufficiency (shock, strangulation eg hernia, drugs eg cocaine and hyperviscosity)
which is most metabolically active part of bowel wall
mucosa - most sensitive to effects of hypoxia
what is the complications of ischaemia of small bowel
resolutionfibrosis, structure, chronic ischaemia, mesenteric angina and obstruction gangrene, perforation, peritonitis, sepsis and death
what is meckels diverticulum
small bulge in SI - result of incomplete regression of vitello-intestinal duct
what is consequence of meckels diverticulum
bleeding, perforation or diverticulitis which mimics appendicitis
what is incidence of tumours in small bowel
primary tumours raresecondary tumours (metastases) much more common eg in ovary, colon or stomach
what primary tumours found in small bowel
lymphomas, carcinoid tumours, carcinomas
characteristics of lymphomas of small bowel
rare, maltomas (b cell) derivedenteropathy associated T cell lymphomas (associated with coeliac disease)treated by surgery and chemo
characteristics of carcinoid tumours
rare, common site is appendixsmall, yellow, slow growing tumourslocally invasive
what is complication of carcinoid tumour
can cause intussusception, obstructionif metastases to liver occur, a carcinoid syndrome occurs producing flushing and diarrhoea
characteristics of carcinoma of small bowel
rare, associated with crohns and coeliacsidentical to colorectal carcinoma in appearance presents late metastases to lymph nodes and liver
what are symptoms of appendicitis
vomiting, abdominal pain, RIF tenderness and increased WCC
what is that pathology of acute appendicitis
acute inflammation (neutrophils - must involve muscle coat), mucosal ulceration, serosal congestion - exudate - and pus in lumen
what are complications of appendicitis
peritonitis, rupture, abscess, fistula, sepsis and liver abscess
what is coeliac disease
abnormal reaction to constituent of wheat flour, gluten, which damages enterocytes and reduces absorptive capacity
what does coeliac disease have strong associations with
HLA-B8, dermatitis herpetiformis and childhood diabetes
what is cause of coeliac disease
gliadin in gluten - tissue injury may be bystander effect mediated by T cells which exist within SI epithelium (making them IELS)
what happens to enterocytes in coeliac disease
increasing loss of them due to IEL mediated damage - leads to loss of villous structure, loss of surface area, reduction in absorption and flat duodenal mucosa
what is the morphology of coeliac disease
increased inflammation in lamina propriaincreased intraepithelial lymphocytes
biopsy results of coeliac disease
mucosa may be endoscopically normal or appear attenuated lesion worse in proximal bowel so duodenal biopsy very sensitive
serology results of coeliac disease
antibodiesanti TTG, anti endomesial and anti gliaidin
what is the metabolic effects of coeliac disease
malabsorption of sugars, fats, amino acids, water and electrolytes - leads to steatorrheareduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (CCK) leading to gallstones
what is the effects of malabsorption (can be managed by diet)
loss of weight, anaemia (Fe, Vit B12, folate), abdominal bloating, failure to thrive, vitamin deficiences
what are other complications of coeliac disease
T cell lymphomas of GI tract, increased risk of small bowel carcinoma, gall stones, ulcerative - jejenoilleitis
what is intestinal failure
inability to maintain adequate nutrition or fluid status via intestines
what causes intestinal failure
obstruction, dysmotility, surgical resection, congenital defect or disease associated loss of absorption
what is intestinal failure characterised by
inability to maintain protein-energy, fluid, electrolyte or micronutrient balace
what are the different kinds of intestinal failure
acute (type 1&2 - 2 weeks) - eg mucositis post chemotherapychronic long term (type 3) - eg short gut syndrome
how is type 1 intestinal failure treated
replace fluid, correct electrolytesparenteral nutrition if unable to tolerate oral food/fluids >7 days post opacid suppression - proton pump inhibitorsoctreotide alpha hydroxycholecalciferol to preserve Mg
what is parenteral nutrition
provision of nutrients by IV route - ultrasound guided
what is complications of parenteral nutrition
pneumothorax / arterial puncture / misplacementsepsis, SVC thrombosis, metabolic bone disease, liver disease
what is type 2 IF
occurs in septic patients, abdominal fistulae and perioperative who may develop complication of feeding
what is treatment for type 2 IF
weeks/months of care (ICU/HDU)Parenteral +/- some enteral feeding
what is the treatment options for type 3 IF
home parenteral nutrition (treatment of choice, esp in SBS), intestinal transplantation, GLP2 (teduglutide) treatment for SBS or bowel lengthening
what is malabsorption
defective mucosal absorption caused by defective luminal digestion, mucosal disease and structural disorders
what are common causes of malabsorption
coeliac disease, crohns disease, post infectious, biliary obstruction, cirrhosis
what are uncommon causes of malabsorption
pancreatic cancer, parasites, bacterial overgrowth, drugs, short bowel
E/O of coeliac disease
intestinal antigen-presenting cells in people expressing HLA-DQ2, or HLA-DQ8, bind with dietary gluten peptides in their antigen binding grooves activate specific mucosal T lymphocytes cytokines mucosal damage
symptoms of coeliac disease
spectrum asymptomatic to nutritional deficiencies - weight loss, diarrhoea, excess flatus and abdominal discomfort
how is coeliac disease diagnosed
IgA anti-tissue transglutaminase test (tTGA)biopsy confirmative
treatment for coeliac disease
gluten free diet
E/O of lactose malabsorption
deficiency of lactase
symptoms of lactose malabsorption
history of induction of diarrhoea, abdominal discomfort and flatulence following ingestion of dairy product
how is lactose malabsorption diagnosed
the diagnosis is confirmed by lactose breath hydrogen test alternative is oral lactose intolerance test
treatment for lactose malabsorption
lactose free diet
E/O of tropical sprue
colonisation of the intestine by an infectious agent or alterations in the intestinal bacterial flora induced by exposure to another environmental agent
what is symptoms of tropical sprue
diarrhoea, steatorrhea, weight loss, nausea and anorexia, anaemia
how is tropical sprue diagnosed
biopsy
what is treatment of tropical sprue
tetracycline and folic acid
E/O of whipple’s disease
tropheryma whippleimultisystem involvement increase in frequency of HLA-B27
symptoms of whipple’s disease
weight loss, diarrhoea, steatorrhoea and absominal distention, arthritis, fever, nutritional defect symptoms
how is whipple’s disease diagnosed
diagnosis is established by demonstration of T.whipplei in involved tissues by microscopy
what is treatment of whipple’s disease
antimicrobial
what is E/O of crohns disease
crohns disease patients with extensive ileal involvement, extensive intestinal resections, enterocolic fistulas and structures leading to small intestinal bacterial overgrowth may develop significant and occasionally devastating malabsorption
what is symptoms of crohns disease
abdominal pain and diarrhoea, fever and weight loss, abdominal tenderness, most classically in right lower quadrant
how is crohns disease diagnosed
endoscopybarium imaging of small bowel mucosal disease, including strictures, ulcerations and fistulaeCT, MRIcolonoscopy - punched out lesions
what is treatment for crohns
steroids, immunosuppressants, azathioprine 6-MP, biological therapy (and TNF)
what is the risk factors for parasitic infections - giardia lamblia
travel to areas where water supply may be contaminated, swimming in ponds
what is symptoms of parasitic infections
diarrhoea, flatulence, abdominal cramps and epigastric pain and nauseasignificant malabsorption with steatorrhea and weight loss may develop
how is parasitic infections diagnosed
stool examination for ova and parasites
what is treatment for parasitic infection
metrondiazole - 1 week
what other parasites apart from giardia lambila can cause parasitic infection
coccidial, strongyloides
what bacteria is involved in small bowel bacterial overgrowth
E.coli or bacteroids
what is E/O of small bowel bacterial overgrowth
diverticula, fistulas and strictures related to crohns disease, bypass surgeries, functional stasis
how is small bowel bacterial overgrowth diagnosed
low cobalamin and high folate levels
what is treatment for small bowel bacterial overgrowth
surgical correction of anatomical blind looptetracyclines 2-3 weeks
what is malnurition
deficit of energy, protein, vitamins and minerals with measurable adverse effects on body
what are the disease related causes of malnutrition
decreased intake, impaired digestion/absorption, increased nutritional requirements, increased nutrient losses
what is consequences of malnutrition
increased infection rate decreased wound healing physical weakness
what acute events can cause GI dysfunction and malnutiriton
sepsis, pneumonia etc fever surgery trauma radiotherapy chemotherapy
what chronic events can cause GI dysfunction and malnurtrition
anorexiaasthenia, depressiondysphagia malabsorption, fistula, diarrhoeainfection (TB, HIV etc)immobility
what are the effects of starvation
decreased metabolic rateslow weight lossdecreased nitrogen lossesearly increases in catecholamines, cortisol, GH then slow fall - insulin decreasedinitial loss of water and sodium, late retention
what are the effects of injury
increased metabolic rate rapid weight loss increased nitrogen losses increase in catecholamines, cortisol, GH - insulin increasedretention
what is used to assess malnutrition
malnutrition universal screening tool (MUST) - look this up
how is anthropometry used to assess nutrition
mid-arm muscle circumference, triceps and grip strength
what biochemical assesments can be used o assess nutritional status
albumin (reduced), tansferrin (reduced), transthyretin (reduced), retinol binding protein, urinary creatinine, IGF-1 (reduced) and micronutrients
what biochemical measures are used in older people in community
vitamins A, C, D and E, albumin and zinc all statistically significantly lower in high risk group compared with low risk group
what is enteral tube feeding
the delivery of nutritionally complete feed directly into gut via tube (nasogastric NG or nasojejunal NJ)used if poor oral untake but functional, accessible GI tract
what is contradictions for ETF
lower GI obstruction, prolonged intestinal ileus, severe diarrhoea or vomiting, high enterocutaneous fistula, intestinal ischaemia
what are the indications for parenteral nurition
poor oral intake (or enteral nutritional intake) and non functional GI tract (eg by IBD, radiation enteritis, short bowel syndrome, motility disorders)
