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Flashcards in GI Session 7 Deck (109):
1

What are the innate physical defences against toxins?

Sight
Smell
Memory
Saliva
Gastric acid
Small intestinal secretions
Colonic mucus
Anaerobic conditions in small bowel and colon
Peristalsis and segmentation

2

What components of saliva allow it to be an effective defence when dealing with toxins?

Lysozymes for G+ve
Lactoperoxidase for G-ve
Complement
IgA
Polymorphs

3

What are the innate cellular defences against toxins in the GI tract?

Neutrophils
Eosinophils
Basophils
Macrophages
Natural killer cells

4

When is eosinophilia seen?

Asthma
Hay fever
Parasitic infection

5

What are the captive immune defences against toxin insult in the GI tract?

B lymphocytes release IgA and IgE for extracellular microbes
T lymphocytes act against intracellular microbes in MALT

6

What is xerostomia?

Decreased salivary flow due to severe illness and/or dehydration

7

How does xerostomia lead to parotitis?

S.aureus overgrowth in mouth --> dental caries --> microbes up Warton's duct --> parotitis

8

What does xerostomia predispose to in the mouth?

Candida albicans (thrush) and lingua villosa nigra (black hairy tongue) due to fungal overgrowth

9

What defences does the oesophagus have against toxins?

Flow of liquids
Peristalsis

10

What defences does the stomach have against toxins?

2.5 l of gastric juice with pH as low as 0.87

11

Does the gastric juice in the stomach kill all bacteria and viruses?

No

12

What defences does the small intestine have against toxins?

Bile acting as a detergent so normally sterile
Proteolytic emzymes
Anaerobic environment
Shedding of epithelial cells
Peristalsis

13

What defences does the colon have against toxins?

Anaerobic environment for water recovery --> faeces 40% bacteria
Mucous layer

14

Why are early morning gastric washings used to diagnose TB?

M.tuberculosis is resistant to gastric acid

15

What viruses are resistant to gastric acid?

Enteroviruses e.g. Hep A, polio, coxsackie and norovirus

16

What effect does achlorhydia have on susceptibility to infection?

Increases

17

What can cause achlorhydia?

Pernicious anaemia
H2 antagonists
PPIs

18

What infections can achlorhydia lead to?

Shigellosis
Cholera
Salmonella

19

What causes pseudomembranous colitis in hospital pts taking PPIs?

C.diff

20

What can lead to loss of mucosa and other colonic defences causing overwhelming sepsis and rapid death?

Intestinal or hepatic ischaemia due to arterial disease, systemic hypotension or intestinal venous thrombosis

21

What toxins can the GI tract be exposed to?

Chemical
Bacterial
Viruses
Protozoa
Nematodes (roundworms)
Cestodes (tapeworms)
Trematodes (flukes)

22

What is a portal blood system?

2 capillary systems in series

23

What are the two capillary systems involved in the hepatic portal system?

Feedin arteriole and draining venule of a villus
Hepatic lobule capillary system

24

What is the purpose of the hepatic lobule capillary system?

Provides bloodflow for highly active cells surrounding bile canaliculi to transport waste materials out of hepatic sinusoids

25

What can cause liver failure?

Viral hepatitis
Alcohol
Drugs
Industrial solvents
Mushroom poisoning

26

What are the consequences of liver failure?

Increased susceptibility to infections, esp bacterial but also fungal
Increased susceptibility to toxins, drugs and hormones
Increased blood ammonia

27

Why do blood ammonia levels rise in liver failure?

Production by colonic bacteria and deamination of a.a. not cleared

28

What is cirrhosis?

Hepatic fibrosis

29

What are the consequences of portosystemic shunting due to portal venous hypertension?

Toxin shunting
Oesophageal Varices
Haemorrhoids
Caput medusae

30

What movement of veins occurs at the oesophogastric and anorectal junctions?

Cross from siting in the serosa to below mucosa

31

What is Caput medusa?

Pressure changes in portal venous hypertension --> bloodflow into obliterated L umbilical vein as the porta hepatis drains into it

32

What does the bloodflow of the tortuous veins in Caput medusa indicate?

Whether they are due to SVC obstruction, IVC obstruction or portal venous hypertension

33

What is Harvey's test?

Assess cause of Caput medusa
Empty veins by applying pressure and observe refill speed: travelling upwards is faster than travelling downwards
Repeat in opposite direction to check

34

Where is GALT found?

Diffusely distributed and nodular in tonsils, Peyer's patches and appendix

35

What are the three sets of tonsils?

Palatine
Lingual
Nasopharyngeal (adenoids)

36

Where do the tonsils drain?

Cervical LN associated with deep jugular vein

37

What is the purpose of iliocaecal lymphatic tissue?

Protect against bacterial reflux from the colon as mucosa here is not sufficient

38

What can cause appendicitis?

Lymphoid hyperplasia at appendix base
Faecolith
Chicken pox --> purulent appendicitis in children

39

What is the pathogenesis of typhoid fever?

Causes inflammation of Peyer's patches in terminal ileum --> perforation --> death

40

What is the pathogenesis of mesenteric adenitis?

RIF pain in children due to adenovirus/coxsackie virus invading LN at terminal ileum

41

Why do chemical toxins such as metals/metaloids/solvents/drugs lead to multi organ failure?

They have developed quicker than our defences to them

42

Which enzyme conjugates bilirubin in the liver?

Glucuronyltransferase

43

Why does urobilinogen not colour urine?

It is soluble

44

What is prehepatic jaundice?

Excessive haemolysis and the liver cannot cope with the excess bilirubin

45

What can cause inherited prehepatic jaundice?

RBC membrane defects
Hb abnormalities
Metabolic defects
Congenital hyperbilirubinaemia
Gilbert's syndrome
Dublin-Johnson syndrome (affected transporter protein)

46

What can cause acquired prehepatic jaundice?

Immune disease
Infection
Drugs
Burns

47

Why are the lab findings in prehepatic jaundice?

Unconjugated hyperbilirubinaemia
Reticulocytosis
Anaemia
Increased LDH
Decreased haptoglobin

48

What causes decreased haptoglobin in prehepatic jaundice?

Binding with Hb

49

What is hepatic jaundice?

Deranged hepatocytes function and swelling of hepatocytes

50

What are congenital causes of hepatic jaundice?

Gilbert's or Crigler-Najjor syndromes

51

What are acquired causes of hepatic jaundice?

Hep viruses
EBV
Autoimmune disease
Alcohol
Haemachromatosis
Wilson's disease
Drugs
Cirrhosis
Widespread hepatic tumours

52

What are the lab findings in hepatic jaundice?

Mixed unconjugated/conjugated hyperbilirubinaemia
Raised AST/ALT
Normal or raised ALP
Abnormal clotting: raised INR and decreased platelets

53

Why might ALP be raised in hepatic jaundice?

Due to cholestasis from swollen cells

54

What is post-hepatic jaundice?

Intra/extrahepatic obstruction of the biliary system blocking passage of conjugate bilirubin

55

What can cause post-healthcare jaundice?

Intrahepatic: hepatitis, drugs, cirrhosis, primary biliary cirrhosis
Extrahepatic (distal to bile canaliculi): gallstones, biliary stricture, carcinoma, pancreatitis, sclerosing cholangitis

56

What are the lab findings in post-hepatic jaundice?

Conjugated hyperbilirubinaemia
Dark urine
Lack of urobilinogen
Raised canalicular enzymes
Normal or increased AST and ALT

57

Why is there no urobilinogen in post-hepatic jaundice?

No bilirubin in bowel so none formed

58

Why might AST and ALT be raised in post-hepatic jaundice?

Mild hepatocyte damage due to build up of pressure

59

What LFTs indicate hepatocellular damage?

Raised aminotransferases (AST and ALT)
Increased gamma-glutamyl transpeptide

60

What LFTs indicate cholestasis?

Raised bilirubin
Raised alkaline phosphatase (ALP)

61

What LFTs indicate impaired synthetic function of the liver?

Decreased albumin
Increased prothrombin (raised INF and decreased platelets)

62

What is the pathogenesis of acute/chronic hepatitis?

Virus, autoimmune, drug or herditary cause --> acute hepatocyte breakdown --> increased aminotransferases and jaundice --> decreased albumin and clotting factors

63

What is alpha-1-antitrypsin disease?

Autosomal recessive condition causing hepatitis and emphysema in bases of lungs

64

What is the Tx for hepatitis caused by alpha-1-antitrypsin deficiency?

Transplant

65

What is Wilson's disease?

Autosomal recessive condition causing copper deposition in liver, basal ganglia, kidney and eyes

66

What is the Tx for hepatitis caused by Wilson's disease?

Penecillamine (chelating agent)

67

What is the pathogenesis of alcoholic liver disease?

Alcohol consumption and probable genetic factors --> fatty change --> alcoholi helatitis --> cirrhosis

68

What are the consequence of alcoholic cirrhosis?

Epilepsy
Hepatocellular carcinoma
Liver failure
Wernicke-Korsakoff syndrome
Encephalopathy
Cerebral atrophy --> dementia

69

What is the pathogenesis of liver cirrhosis?

Chronic inflammation --> liver cell necrosis --> nodular regeneration and fibrosis --> increased bloodflow resistance and deranged liver function

70

What is the pathogenesis of biliary cirrhosis?

Autoimmune chronic destruction of bile ducts --> jaundice, pruritis, xanthelasma and hepatosplenomegaly

71

What is Haemachromatosis?

Autosomal recessive condition causing deposition of iron in heart, pancreas, pituitary, liver and skin

72

What is the Tx haemachromatosis?

Venesection

73

What are the consequences of liver cirrhosis?

Spontaneous bacterial peritonitis
Jaundice
Anaemia
Brushing
Palmar erythema
Dupuytren's contracture
Portal hypertension

74

What can cause obstruction of the portal vein leading to portal hypertension?

Congenital
Thrombosis
Extrinsic compression

75

What can cause obstruction of bloodflow in the liver leading to portal hypertension?

Cirrhosis
Hepatoportal sclerosis
Schistosomiasis
Sarcoidosis

76

What are the consequences of portal hypertension?

Splenomegaly
Ascites
Spider naevi
Caput medusa
Oesophageal/rectal Varices

77

What causes spider naevi in portal hypertension?

Resp ducked oestrogen removal by the liver

78

What is fulminant hepatic failure?

An acute and/or severe decompensation of hepatic function with onset of hepatic encephalopathy within 2 months of liver disease diagnosis

79

What is seen in fulminant hepatic failure before supportive treatment +/- transplant?

Jaundice
Encephalopathy
Decreased level of consciousness
Hypoglycaemia
Decreased K+/Ca2+
Haemorrhage

80

What indicates urgent transplant in fulminant hepatic failure?

Hypoglycaemia

81

What can cause fulminant hepatic failure?

Hep A,D,E
Drugs
Reye's syndrome
Alcohol
Pregnancy

82

What is hepatic encephalopathy?

Reversible neuropsychiatric deficit caused by raised toxin levels in the blood

83

Why does ammonia especially cause hepatic encephalopathy?

Urea cycle function impaired --> small ammonia can pass through the BBB causing toxicity and brain swelling

84

What are the S/S of hepatic encephalopathy?

Flapping tremor
Decreased level of consciousness
Personality changes
Constructional apraxia
Slow, slurred speech

85

What can a liver failure pt experience that leads to development of hepatic encephalopathy?

Sepsis
Infection
Constipation
Diuretic Tx
Alcohol withdrawal

86

What are the majority of liver metastases due to?

50% from colorectal tumours metastasising via portal venous drainage

87

How does the incidence of primary liver tumours compare to the incidence of liver metastases?

20x more metastases

88

What type of benign tumour can develop in the liver?

Haemangioma
Focal nodular hyperplasia
Polycystic liver disease

89

How does the gallbladder change depending on how long it takes a gallstone to form?

Long time --> shrunken, fibrotic gallbladder
Short time --> large gallbladder

90

What can prevent passage of bile from the liver to the duodenum?

Gallstones
Gallbladder structures
Gallbladder atresia in neonates
Infection
Inflammation
Neoplasia

91

What are the risk factors for developing cholelithiasis (gallstones)?

Female
Age
Obesity with rapid weight loss
Diet
Multiparity
Ileal disease
Resection --> interruption of enterohepatic circulation
Haemolytic disease

92

What three type of gallstones can develop?

Mixed
Pure cholesterol
Pigment stones

93

What is the most common type of gallstone?

Mixed

94

What is found in mixed gallstones?

Cholesterol
Calcium
Pigment

95

What is the pathogenesis of biliary colic?

Impaction of stone in Hartman's pouch --> gallbladder contraction--> post prandial pain

96

What is the pathogenesis of cholecystitis?

Stones --> localised oedema --> mucosa ulceration --> fibropurulent exudate --> pain, SIRS, pyrexia, sepsis

97

What is ascending cholangitis?

Where stone blocks common bile duct and causes inflammation proximal to blockage

98

What is Charcot's triad?

RUQ pain + jaundice + fever
Indicates life threatening condition requiring urgent Abx

99

How do gallstones lead to biliary enteric fistula and gallstone ileus?

Fistula eroded between gallbladder and duodenum --> large stone obstructs ileum

100

What are 90% of pancreatic cancers?

Ductal adenocarcinoma

101

What are the causes of acute pancreatitis?

Gallstones
Ethanol
Trauma
Steroids
Mumps
Autoimmune
Scorpion bite (Trinidad)
Hyperlipidaemia
ERCP/iatrogenic
Drugs

102

What happens in acute pancreatitis?

Duct obstruction --> juice and bile reflux
Acinar damage --> reflux
Protease--> tissue destruction
Lipase--> fat necrosis
Elastase--> BV destruction

103

What are the S/S of acute pancreatitis?

Severe pain
Vomiting
Dehydration
Shock
Ecchymosis
Raised amylase, ALP, bilirubin and reduced calcium
Glycaemia

104

What is the pathogenesis of chronic pancreatitis?

Chronic alcoholism/CF/inherited/biliary disease --> chronic inflammatory condition --> parenchymal destruction, fibrosis, loss of acini, duct stenosis

105

What are the S/S of chronic pancreatitis?

Pain
Malabsorption--> steatorrhoea
Decreased albumin
Weight loss
DM
Jaundice

106

What Tx can be used in acute pancreatitis?

Supportive: ITU, fluids ?Abx

107

What Tx can be used in chronic pancreatitis?

Lifestyle changes
Steroids
Supportive

108

What is a Whipple procedure?

Surgical procedure which removes gallbladder and uses Y loop to reroute small intestine around pancreas to treat S/S of pancreatic disease

109

What S/S indicate use of Whipple procedure?

Palpable gallbladder
Pain due to coeliac trunk compression
Vomiting
Carcinomatosis
Malabsorption
DM