Gastroenterology Flashcards
What are the sites of absorption in the intestine for iron,
IRON = proximal duodenum
-> needs acidic environment
FOLIC acid = first 1/3 small intestine (duodenum/jejunum)
VITAMIN B12 = ileum
-> needs intrinsic factor
Which part of the small intestine has maximal absorption of zinc?
Proximal jejunum
All three segments (duodenum, jejunum and ileum) have the ability to absorb zinc
What is the MoA of cholera in producing diarrhoea?
(1) Cholera enterotoxin -> activation of ADENYLATE CYCLASE -> increase cAMP in intestinal epithelial cells
(2) cAMP on intestinal epithelial transport -> stimulation of active Cl secretion (crypts) and inhibition of Na-Cl absorption (villi)
Why is ORS important in treating cholera?
Cholera enterotoxin (cAMP) does NOT inhibit glucose-stimulated Na (and thus fluid) absorption
What is the MoA of ORS?
Glucose to stimulate Na and fluid absorption in the small intestine via cyclic AMP-independent process
Glucose absorption requires luminal Na -> absorption markedly enhanced by the presence of luminal glucose
Which part of the small intestine (microscopic) does electrolyte absorption vs secretion take place?
Electrolyte ABSORPTION = villi (peaks)
SECRETION = crypts
What is the major site of the intestine for absorption?
Jejunum
Majority of nutrient absorption takes place in jejunum, EXCEPT:
Iron = duodenum Folate = duodenum and jejunum Calcium = duodenum and upper jejunum (transcellular active transport process); throughout length of intestine (paracellular, passive process) Vitamin B12 = terminal ileum Bile salts = terminal ileum
Name the disaccharides and their components (monosaccharides)
Maltose = glucose + glucose
Lactose = glucose + galactose
Sucrose = glucose + fructose
*Remember, glucose in all; two of the three monosaccharides start with ‘G’
What syndromes are associated with Hirschsprung disease?
Mowat Wilson syndrome Down syndrome (T21) Bardet-Biedl syndrome Smith-Lemli-Opitz syndrome Waardenburg syndrome
What are the symptoms caused by deficiency in the fat-soluble vitamins?
A = night blindness (late), scaly skin, infection susceptibility of epithelia (lung, GI, GU)
-> vitamin A involved in maintenance of epithelial functions
D = rickets, craniotabes (softening skull), rachitic rosary, growth plate widening
E = haemolysis (usually 2nd month life), neurologic manifestations (cerebellar disease, posterior column dysfunction, retinal disease)
-> vitamin E functions as in antioxidant
K = bleeding (GI, mucosal, cutaneous)
-> required for clotting factors
What is the initial finding (usually) in vitamin E deficiency?
Loss of deep tendon reflexes
-> limb ataxia, truncal ataxia, dysarthria, opthalmoplegia (limited UPward gaze), decreased proprioception
What is an example of diarrhoea getting worse with ORS instead of IVT?
Glucose-galactose malabsorption
Autosomal RECESSIVE disorder = inheritance of two defective copies of the SGLT1 gene (chromosome 22)
MoA = lack of transportation (the protein product of SGLT1) of the broken down lactose (into glucose and galactose by lactase) from the lumen into intestinal cells -> osmotic diarrhoea
What syndromes is coeliac disease associated with?
Down (T21)
Turner
William
What are the types of autoantibodies seen in autoimmune hepatitis type 1 vs. 2?
Type I
- Antinuclear (ANA) antibodies
- Anti-smooth muscle (anti-SMA) antibodies
Type II
- Antiliver-kidney microsomal-1 antibodies (anti-LKM-1)
- Antiliver cytosol-1 antibodies (anti-LC-1)
Both typically have hyPERGAMMAglobulinaemia (IgG levels >16g/L)
Type II > I in severity Type II (almost exclusively) female
What are the 3 Rome criteria functional disorders for abdominal pain?
FUNCTIONAL ABDOMINAL PAIN (school age) 1. Periumbilical pain 2. Normal growth 3. Appetite not usually affected 4. Symptoms better on weekend/vacation 5. Social stressors exacerbate
FUNCTIONAL DYSPEPSIA (school age/adolescent) 1. Midepigastric 2. Correlation to meals 3. Normal growth
IRRITABLE BOWEL
(adolescent)
1. Lower abdomen
2. Female
3. Pain improves with defacation
4. Frequent changes in stool caliber/frequency
5. Normal growth and appetite
What disease is abdominal pain that wakes from sleep typically seen in?
H. pylori infection
What are the major differences between omphalocele vs. gastroschisis?
OMPHALOCELE
- Central defect (umbilical ring)
- Covering membrane (peritoneal membrane internal, amniotic membrane external)
- Congenital anomalies (thoracoabdominal syndorme, BWS, lower midline syndrome, trisomies)
- Staged surgery
- +/- midgut volvulus
- Lower survival rate (affected by congenital)
GASTROSCHISIS
- Lateral (right) - accident involving right umbilical vein or omphalomesenteric artery
- No membrane
- Midgut volvulus
- Immediate surgery
Where are the two vomiting centers of the brain located?
Vomiting center (neural) = in the nucleus solitarius in MEDULLA
Chemoreceptor trigger zone (chemical) = floor of 4th ventricle
What is the best test for chronic vomiting?
Endoscopy
Main causes = oesophagitis, gastritis
Less common = duodenitis, giardiasis
What other disease is cyclic vomiting associated with?
Migraines
What is the treatment for cyclic vomiting?
Cyproheptadine (1st choice < 5 years)
Propanolol
Amitriptyline
Which grains contain gluten?
BRWS
B - barley
R - rye
W - wheat
S - spelt (a species of wheat)
Oats previously thought to be harmful - but appears to be from contamination with wheat flour
-> still included in gluten-free diet
Which patients are at high-risk for coeliacs?
- First and second-degree relatives with coeliacs
- Down syndrome (T21)
- T1DM
- Selective IgA deficiency
- Autoimmune thyroiditis
- Turner syndrome
- William syndrome
- Juvenile chronic arthritis
What is the best serologic test for diagnosis of coeliac disease?
IgA antibodies against tissue transglutaminase (tTG-IgA)
= highly specific, sensitive and cost-effective
OTHER
= IgA antibodies to endomysium (EMA)
-> as accurate as tTG-IgA, but more expensive and operator interpretation-dependent
