GASTROINTESTINAL TRACT Flashcards

Question

Briefly explain the MOA of PPIs and H2 antagonists. Which one is more potent and why?

Answer 1

``` CO2 + H2O ⇋ H2CO3. ⇋ HCO3 + H+ - Bicarbonate is exchanged for chloride CO2 and H2O from blood converted for carbonic acid and then broken down into bicarbonate and hydrogen ion. - Process mediated by CA. - Proton comes from this equation ``` H+K ATPase pump out Protons (H+) and Chloride channels pump out Chloride ions: H+ + Cl- → HCl - Proton goes into the stomach lumen - PPIs work at this point to block HCl production When we eat, distention → Gastrin → Stimulate enterochromaffin-like cells release histamine → Stimulates acid secretion (fuels H+K ATPase pump) - H2 antagonists block histamine activity and therefore less acid - Not as potent as shutting down the entire pump (ie. PPIs)

Answer 2

D is false. Antibiotics only used for H.Pylori associated dyspepsia

Answer 3

Age >/= 60 | Alarm features

Answer 4

PPO, clarithromycin, amoxicillin - 7 day regimen.

Answer 5

1. Goblet cells - mucous secretion 2. Paneth cells - antimicrobial peptide production - producing defensins which limit microbial load in the lumin, ther are alpha (in small intestine) and beta (in colon) subtypes 3. Microfold cells - transcellular transport from the lumen to APC's in the Peyers Patches 4. Tight Junctions - forming the physical barrier

Answer 6

Answer D. Induction of T-regulatory cells is via the conversion of vitamin A to retinoic acid (via dendritic cells). The retinoic acid then binds to TGF-beta for induce the naiive T-cells into T-regulatory cells

Answer 7

1. Inflammatory bowel diseases - abnormal Th1 and Th17 responses, defective function of Tregs, defective defensins or inability of innate cells 2. Coeliac Disease - abnormal CD4+ response to gliadin - leading to an inflammation in the small intestine 3. Food allergies - abnormal Th2 immune response to food antigens 4. Tumours - due to prolonged immune response to commensal bacteria

Answer 8

C is correct A - Cl- channels are CFTR, mediated by cAMP B - DRA is a Cl-, HCO-3 exchanger D - Distal colon and rectal epithelium have electrically tight junctions therefore have 0 ion flow paracellularly

Answer 9

1. Cephalic phase - the thought, taste, smell, chewing and/or swallowing of food stimulates the vagus nerve to activate parietal and G-cells via ACh and Gastrin 2. Gastric phase - distension of the stomach stimulates local enteric and vasovagal reflexes to secrete ACh and Gastrin which activate parietal and G-cells 3. Intestinal Phase - protein digestion products in the duodenum and duodenal distension stimulate enteroendocrine cells via CCK and then inhibit secretion via the vasovagal path using secretin, GLP-1 and PYY

Answer 10

Frequent stools (>3/day) and/or Altered/decreased consistency of stools

Answer 11

B is correct A - this is mostly correct except it DOES resolve on fasting C - small bowel diarrhoea does NOT have blood and mucous, this would be more likely found in large bowel diarrhoea D - this is mostly correct except that its a smaller volume not a large volume

Answer 12

``` IBS Bile acid Dietary (FODMAP, lactase deficiency, excess alcohol etc.) Colonic neoplasia IBD Coealiac disease Drugs (AB's, NSAIDs, Magnesium etc.) Overflow diarrhoea ```

Answer 13

Coeliac disease is an immunologically mediated disorder of the small intestine caused by dietary exposure to triggering proteins in wheat, barley and rye

Answer 14

D is incorrect - incomplete digestion of gliadins and then concurrent gliadin-tTG complex presentation to CD4+ T cells that plays a role in the pathogenesis

Answer 15

Antibody testing Small bowel biopsy HLA testing (adjunct)

Answer 16

IBS is a functional disorder of the GIT characterised by chronic abdominal pain and altered bowel habits Clinical Features - abdominal pain - altered bowel habits (diarrhoea, constipation or alternating) - bloating - flatulence

Answer 17

Absolute - attained growth where weight is <3rd centile, height <5th centile and/or weight is <20% of the ideal height:weight ratio Relative - relative rate of growth Where there is a fall from the previous growth curve of equal to or more than 2 centiles

Answer 18

Answer - E It isnt a decreased need but rather an increased need e.g. due to neoplasms, congenital heart disease or chronic illness causing an imbalance of requirement/expenditure that leads to the failure to thrive

Answer 19

Any of the below; 1. carer preoccupation with own issues (post natal depression) 2. carer external demands (large families) 3. drug/alcohol abuse 4. poverty 5. domestic violence 6. absence of support 7. lack of parenting support 8. parental intellectual disability

Answer 20

Rotavirus, cytomegalocirus (CMV), norovirus

Answer 21

Answer - A Giardia is a parasitic infection of the GIT

Answer 22

Faecal-oral, waterbourne/contaminated water, person-person

Answer 23

- Attack by gastric lipase and bile emulsifies large fat droplets - Pancreatic enzymes (pancreatic lipase - require colipase) breakdown TAGs to monoglycerides and FFA - Bile salts form micells = Hydrophobic core and hydrophillic surface - Micelles fuse with the enterocytes - Brush border enzymes (phospholipase, sphingomyelinase) break down micelle - Monoglycerides and FFA reconsittutded into chylomicrons for transport to lymphatic system for circulation OR small chain TAGS can bypass system and enter portal venous system

Answer 24

B. Iron absorption occurs in duodenum

Answer 25

``` 1. Basal secretion → Interdigestive period Maximal during MMC 2. Cephalic phase → Sight, smell, taste of food 20-25% maximal Mainly acinar in origin Mediated by vagus → Ach (+VIP) 3. Gastric phase → Antral distension 10% maximal Mainly acinar in origin Mediated by vagus → Ach 4. Intestinal phase → Presence of H+, aromatic L-amino acids, peptides and fatty acids in lumen 50-80% maximal Ductal and acinar in origin Mediated by Secretin (H+) and CCK ```

Answer 26

Maltase → Breaks down maltose to glucose Lactase → Breaks down lactose to glucose and galactose Sucrase → Breaks down sucrose to glucose and fructose

Answer 27

C. Gastrin stimulate PARIETAL cells to release HCl which CHIEF cells release pepsinogen

Answer 28

Fat malabsorption = Polarising crystals | Fat maldigestion = Globules of fat

Answer 29

UC = Confined to the colon, begins in rectum and travels upwards. - Mucosa and submucosa inflammation that is CONTINUOUS - Superficial ulcers - Rarely strictures and no granulomas CD = Entire GIT can be affected - Transmural inflammation that is DISCONTINUOUS - Deep ulcers and fissures - Strictures and granulomas - Fistulae - Cobblestone mucosa

Answer 30

B is true. A. UC commonly associated with bleeding C. False as shown to be ineffective in CD (used in UC instead) D. False as non-smokers showed higher risk than ex-smokers for UC

Answer 31

 Infection/destruction of villi tips  Repopulated by immature secretory cells = Decreased functional capacity (lack of absorption in small intestine)  Osmotic diarrhoea from incompletely absorbed nutrients

Answer 32

o Bile production and excretion o Metabolism of fats, proteins, and carbohydrates o Glycogen synthesis and storage o Synthesis of clotting factors and plasma proteins (prothrombin is ONLY produced in liver) o Blood detoxification

Answer 33

C is false as diaphragmatic surface only contacts diaphragm

Answer 34

• Kupffer Cells: o Phagocytic cells that form lining of sinusoids in liver o Function – Phagocytosis of bacteria/virus, debris, RBCs, protein complexes • Ito Cells: o Also called Perisinusoidal cells or Hepatic stellate cells o Found in perisinusoidal space (just outside sinusoids) o Function – Secrete collagen in response to tissue damage, leading to fibrotic cirrhosis • Pit Cells: o Found in perisinusoidal space o Function – Natural killer cells of liver

Answer 35

D is true. The below are false due to A. ALP is also contained in the bone and intestine. Elevated GGT in combination with elevated ALP can indicate liver disease. B. Serum albumin produced in liver and therefore decreased in chronic liver disease C. Vitamin K is low due to low bile (produced by liver) which is required for absorption of Vitamin K from diet (Vit. K is fat soluble)

Answer 36

o Central adiposity o Dyslipidaemia o Abnormal blood glucose OR insulin resistance (i.e. Pre-diabetes) o Hypertension

Answer 37

Non-alcoholic Fatty Liver (NAFL) = Hepatic steatosis with NO hepatocyte injury. (nil inflammation). Also called “Simple Steatosis” Non-alcoholic Steatohepatitis (NASH) = Hepatic steatosis with hepatocyte ballooning, inflammation, and fibrosis → May progress to cirrhosis

Answer 38

- Excessive alcohol consumption - Hepatitis C - Medications (e.g. methotrexate, corticosteroids) - Starvation - Lipodystrophy

Answer 39

Respiration - tachypnoea Capillary refill - prolonged (>2seconds) Skin turgor - recoil 2 seconds or greater

Answer 40

Answer D --> this is an antihistamine MOA of anti-diarrhoeals: activating opioid receptors on the GI wall decreases motility and hence increases fluid absorption.

Answer 41

Acute: food poisoning, motion sickness, alcohol excess, pregnancy, chemo, post-operation, head injury, acute abdominal injury, diabetic ketoacidosis Chronic: mechanical obstruction, untreated reflux, peritoneal inflammation, cancer, metabolic/endocrine disorder (diabetes, thyroid), medications, gastroparesis, neurological disorder (migraine, parkinsons), anxiety/depression

Answer 42

Answer B Incorrect A - the best route is to try another antiemetic with a different MOA C - there are numerous different causes of nausea and vomiting, all havying varying effects on DA, 5HT, H1, cholinergic and NK1 pathways (hence why the above is effective) D - antiemetics can be given orally, rectally or parenterally

Answer 43

Answer - D Incorrect A - E can have lead to chronic infection in immunosuppressed patients but A is only ever an acute infection B - No, Hep B is a partially dsDNA virus C - Hep D does require Hep B but this is to form the envelope, not the surface antigens

Answer 44

Where the HBsAg (surface antigen) is +ve, the patient may have an acute or chronic infection - If its acute they will also have the presence of IgM - If its chronic they will not be +ve for IgM ``` Where HBsAg (surface antigen) is -ve the patient could be susceptible, recovered/resolved HepB or vaccinated - If they are succeptible they will be -ve for both anti-HBs and anti-HBc ``` * HBc - core antigen and HBs - surface antigen - If they are +ve for both anti-HBs and anti-HBc, this means they have a resolved HepB infection * they have antibodies to both the surface and the core antigens - If they are +ve for only the anti-HBs the patient has been vaccinated * as the vaccine is an inactive form there was no replication and therefore no exposure of the core antigen - hence the vaccinated are only immunised against the surface antigen

Answer 45

``` Malnutrition (muscle wasting, loss of fat deposits, thinning of the skin) Spider Naevi Palmar Erythema Scratch Marks Hyperpigmentation Feminisation in males ``` Decompensation Fluid retention --> ascites, peripheral oedema Jaundice & excessive bruising

Answer 46

3 components 1. portal hypertension leads to splanchnic vasodilation --> decreased blood vol --> RAAS --> Na and H20 retention--> inadequate compensation --> more Na and H20 retention --> ascites 2. portal hypertension leading to splanchnic vasodilation --> increases splanchnic capillary pressires --> lymph production outweighs return --> fluid build up --> ascites 3. decreased albumin --> ascites

Answer 47

progressive renal failure assoc. w/ advanced cirrhosis and ascites - gradual rise in creatinine, and urine output failure - NIL intrinsic renal disease - exclusion of other causes

Answer 48

Answer - C Incorrect A. only 50% of those with a GI bleed and cirrhosis are due to varices, may others can be related to peptic ulcer gisease, coagulopathies etc. B. this is mostly correct though the thin walled vasculature does not cause obstruction but rather expands and ruptures --> variceal bleeding D. These are good predictors of risk

Answer 49

``` platelet disorders decreased synthesis of coagulation factors vit-K deficiency-related coagulopathy dysfibrinogenaemia fibrinolysis DIC ```

Answer 50

Answer D - an accurate assessment is difficult to make in these patients because of fluid retention and hypoproteinaemia

Answer 51

o Pre-Hepatic = Pathology occurring prior to liver (with normal liver function)  Increased haemolysis  Neonatal jaundice – Due to breakdown of foetal Hb for replacement, and immature liver metabolism ``` o Hepatocellular = Pathology occurring within liver due to diseased hepatocytes, resulting in cell necrosis or defective bilirubin metabolism  Acute • Viral hepatitis • Hepatoxic drugs – e.g. alcohol, paracetamol  Chronic • Viral hepatitis • Autoimmune hepatitis • Wilson’s disease • ALD and NAFLD ``` o Post-Hepatic = Pathology occurring after conjugation of bilirubin in liver, due to obstruction of bile duct and canaliculi  Malignancy  Gallstone

Answer 52

D. Require HCV-RNA Acute = Positive Past = Negative Chronic = Positive - can look at erratic elevations of ALT and signs of liver failure to distinguish from acute

Answer 53

1. Oxidising ethanol to acetaldehyde --> Mediated by alcohol dehydrogenase (MEOS - CYP450 mainly in chronic high consumption) 2. Aldehyde dehydrogenase oxidising acetaldehyde to acetic acid 3. Acetic acid converted to acetyl coa and into citric acid cycle

Answer 54

Cirrhosis = Extensive fibrosis and regenerative nodules disrupt the normal architecture of liver Pathogenesis: 1. Hepatotoxins or Immune response (e.g. HBV) 2. Hepatocyte and connective tissue destruction 3. Activation of Ito cells 4. Fibrosis of ECM 5. Nodular regeneration of remaining liver parenchyma

Answer 55

C. is false. | HBV and HCV are the most common viral hepatitis to result in cirrhosis and HCC

Answer 56

1. Liver metabolism --> impairment will affect the clearance of medications, also best to decrease doses of hepatotoxic medications 2. Bleeding tendencies --> there is a likelihood that a patient with liver disease will also have coagulopathies or thrombocytopaenia 3. Transmission of hepatitis viruses (most specifically HCV as there is no immunisation for this) --> adequate sterilisation protocols MUST be implemented and followed

Answer 57

C is correct A - this is almost true, though it results in downregualtion of the receptors B and D- withdrawal is not really associated with the receptors but rather with counteradaptive changes, ie. upregulation of cAMP in benzodiazepine use so that when the drug is ceased a higher than normal level of cAMP is still produced and the patient then suffers the effects (anxiety, insomnia etc. - opposite effects to the drug)

Answer 58

as per DSM-V 11 criteria, should you fulfil 2-3 (mild), 4-5 (moderate) or 6-7 (severe) criteria included; ``` large amounts/longer time used inability to quit increased time obtaining substance craving tolerance withdrawal recurrent/consistent use decreases in social activity unable to carry out obligations due to use continued use in the face of persistent social problems caused by use ```