Gastroenterology

Question 1

Where and how is Vit b12 absorbed?

Answer 1

1. in the terminal ileum
2. Dietary vitamin B12 requires intrinsic factor, a glycoprotein secreted by the gastric parietal cells, for absorption in the terminal ileum. It is transported in the blood by haptocorrin and transcobalamin.

Question 2

The presence of hematochezia (bright red blood) is generally associated what?

Answer 2

with colonic bleeding, although it may result from a brisk upper bleed.

Question 3

The presence of melena—passage of black, tarry stools—generally results from what?

Answer 3

significant blood loss proximal to the ileocecal valve, including an upper gastrointestinal bleed. The color results from bacterial breakdown of the hemoglobin.

Question 4

most likely cause of painless rectal bleeding in children >1 year?

Answer 4

meckels polyps

diagnose with

Question 5

how does the addition of starch to ors help with water absorption?

Answer 5

fermentation to SCFA that can then be absorbed, yep its a thing. The addition of high-amylose maize starch (HAMS), a microbially-fermentable (or ‘resistant’) starch, to ORS results in delivery of non-absorbed carbohydrate to the colon where it is fermented to SCFA

Question 6

how is dietary iron absorbed?

Answer 6

duodenum and proximal jejunim

Question 7

where is calcium absorbed

Answer 7

predominantly absorbed in the duodenum and upper small intestine

Question 8

genetic causes of acute pancreatitis?

Answer 8

• Cationic trypsinogen gene (PRSS1)
• Chymotrypsin C gene (CTRC)
• Cystic fibrosis gene (CFTR)
• Trypsin inhibitor gene (SPINK1)

Question 9

what minimised trypsin activation in the pancreas?

Answer 9

the digestic proteases are stored in low calcium (6.3 pH secretory granules - zymogen), protease inhibitors in the cytoplasm also exist. this means they won’t get changed from pro-enzymes to super digesty enzymes.

Question 10

How do H2 blockers work?

Answer 10

they act on the H2 (histamine) for gastric acide secretion in the parietal cells on the GI system (from the enterochromaffin life cells)

Question 11

How do PPI’s work?

Answer 11

They do so by irreversibly inhibiting the stomach’s H⁺/K⁺ ATPase proton pump at the luminal membrane of the parietal cell in the GI tract

Question 12

why do you check total igA in coeliac screening?

Answer 12

if total iGa is low, you can’t count on the EMA anti igA to mean anything, must use other means

Question 13

what is the ddx for protein losing enteropathy and what would you look for?

Answer 13

IBD: symptoms
CHD: heart symptoms/signs
SLE: signs
coeliac: diarrhoea, weight loss, malabsoprtion, check igA and EMA IgA, iron deficiency and anaemia
CVID: check lymphocyte subsets and Ig
Primary intestinal telangectasia: liver function normal, loss of protein, ascites, chronic diarrhea, malabsorption

Question 14

what are the categories of disorders of malbsorption?

Answer 14

A) mucosal

Question 15

What lipid can be directly absorbed into the hepatic circulation?

Answer 15

medium chain fatty acids

Question 16

what are the extra gastrointestinal manifestations of IBD?

Answer 16

Uveitis
Orofacial granulomatosis
Pyodermis gangrnosum, erythema nodosum
Liver: overlap into autoummne hepatitis and primary sclerosing cholangitis

Question 17

what is the gene most highly associated with Crohn disease?

Answer 17

NOD2 - stricturing disease

Question 18

What is ABCB4 associated with?

Answer 18

progressive familial intrahepatic cholestasis (PFIC or MDR deficiency - high GGT, jaundice, itch).

Question 19

What is a mutation in JAG1 associated with?

Answer 19

allagille syndrome & tetralogy of fallot

Question 20

What is a mutation in MYOSB associated with?

Answer 20

microvillous inclusion disease (congenital diarrhoea, TPN, IF, SB transplant

Question 21

what is the best way to measure vitamin D and why?

Answer 21

of 25-D is the standard method for determining a patient’s vitamin D status.

Vitamin D is transported bound to vitamin D–binding protein to the liver, where 25-hydroxlase converts vitamin D into 25-hydroxyvitamin D (25-D), the most abundant circulating form of vitamin D. Because there is little regulation of this liver hydroxylation step,

Question 22

how does sunlight catalyse vitamin d reaction?>

Answer 22

Cutaneous synthesis is normally the most important source of vitamin D and depends on the conversion of 7-dehydrochlesterol to vitamin D 3 (3-cholecalciferol) by ultraviolet B (UVB) radiation from the sun.