Lower GI Disorders Flashcards

1
Q

Which artery supplies the proximal colon?

A

Superior mesenteric artery

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2
Q

Which artery supplies the distal colon?

A

Inferior mesenteric artery

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3
Q

Which venous vessels drain the colon?

A

Inferior and superior mesenteric veins draining into the portal vein

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4
Q

What structures reside within the submucosal space?

A

Submucosal glands and Meissner’s plexus

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5
Q

Which molecule is secreted by the submucosal glands, lubricating the mucosal surface?

A

Mucin

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6
Q

Between which two layers does the myenteric plexus reside?

A

Intermediate between the circular and longitudinal muscles within the muscularis layer

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7
Q

Where are the myenteric plexus ganglia located in relation to the taenia coli?

A

Concentrated deep to the taenia coli

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8
Q

Which nerve provides the parasympathetic supply to the ascending and proximal transverse colon?

A

Vagus nerve

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9
Q

Which nerves provides parasympathetic supply to the distal transverse and descending colon?

A

Pelvic nerves

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10
Q

What is the sympathetic supply of the colon?

A

Pre-ganglionic fibres arise from the thoracolumbar spinal cord

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11
Q

Which nerve controls the external anal sphincter?

A

Pudenal nerves

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12
Q

What are the nerve roots of the pudenal nerves?

A

S1-S3

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13
Q

What is Hirschprung;s disease?

A

Characterised by a congenial absence of myenteric and Meissner’s ganglion.
• Peristalsis is impaired due to unstimulated muscular contractions within the muscularis layer.
• Obstruction  Constipation.
• There is an absence of propulsive peristalsis and mass contraction in the aganglionic segment.

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14
Q

What are the inflammatory causes of lower GI tract disorders?

A

IBD and microscopic colitis

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15
Q

What are the infective causes of lower GI tract disorders?

A

C. difficile

E. coli

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16
Q

What are the structural causes of lower GI tract disorders?

A

Diverticular disease
Haemorrhoids
Fissures

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17
Q

What are the functional causes of lower GI tract diosrders?

A

IBS

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18
Q

What are the neoplastic causes of lower GI tract disorders?

A

Colonic polyps

Colon cancer

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19
Q

What are the two causes of IBD?

A

Ulcerative colitis

Crohn’s disease

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20
Q

What is ulcerative colitis?

A

Inflammatory disorder characterised by diffuse inflammation of colonic superficial mucosa.

No granulomas

Extends continuously and proximally from the rectum

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21
Q

Which GI organ is always concerned with ulcerative colitis?

A

Rectum

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22
Q

What is proctitis?

A

Inflammation of the rectum

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23
Q

What is pancolitis?

A

Inflammation of the entire colon

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24
Q

What term describes ulcerative colitis of the rectum and sigmoid colon?

A

Proctosigmoiditis

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25
Q

What is distal colitis?

A

Diffuse continuous inflammation from the rectum to the ascending colon

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26
Q

What are the symptoms concerned with ulcerative colitis?

A

Patients present with severe and frequent rectal bleeding, diarrhoea, and blood in stool (detected on digital rectal examination)

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27
Q

What is Crohn’s disease?

A

Characterised by transmural inflammation of the gastrointestinal tract, predominantly in the terminal ileum and perianal locations

Skip lesions

inflammation can penetrate through the serosa, giving rise to perforations and fistulae

Inflammatory infiltrate initially begins around intestinal crypts, developing into ulcerations of the superficial mucosa.
• Inflammation progresses to involve non-caseating granulomas (all layers of the intestinal wall and the mesentery are affected).
• Granulomatous inflammation is characteristic of CD.
• Strictures are narrowing of the bowel due to inflammation.
N.B: Involvement of the terminal ileum will disrupt bile acid absorption  Steatorrhea and fat-soluble vitamin deficiency.

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28
Q

Which areas of the GI tract does Crohn’s disease predominantly affect?

A

Terminal ileum and perianal locations

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29
Q

What are the characteristic features of Crohn’s disease?

A
Skip lesions
Fistulae
Transmural inflammation 
Strictures
Non-caseating granulomas
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30
Q

What is a fistula?

A

Inflammation can penetrate through the serosa giving rise to perforation and fistulae

31
Q

What type of granulomas form in Crohn’s disease?

A

Non-caseating granulomas

32
Q

What is a stricture?

A

Narrowing of the bowel due to inflammation

33
Q

What are the side effects concerned with Crohn’s disease of the terminal ileum?

A

Disrupts bile reabsorption, manifesting as steatorrhea

34
Q

Which gender is most likely to be affected by Crohn’s disease?

A

Females (1.5:1)

35
Q

What are the symptoms of Crohn’s disease?

A
  • Abdominal pain (Right lower quadrant and peri-umbilical regions common – ileitis).
  • Prolonged diarrhoea
  • Perianal lesions (skin tags, fistulae, abscesses, scarring or sinuses)
  • Bowel obstruction – strictures  Manifests as bloating, vomiting and constipation.
  • Fever
  • Abdominal tenderness
36
Q

What are the symptoms concerned with colitis?

A
  • Bleeding
  • Mucus
  • Urgency- hallmark of lower-rectal disorder due to sensory changes. Urgency occurs when the arrival faeces in the rectum causes strong contractions and precipitate anal relaxation.
  • Diarrhoea
37
Q

What is urgency?

A

occurs when the arrival of faeces in rectum results in strong contractions and precipitate anal relaxation

38
Q

What are the symptoms of perianal inflammation?

A
  • Anal pain
  • Leakage
  • Crohn’s disease is fistulating and associated with deep ulcerations.
39
Q

What are the symptoms associated with small bowel disease?

A
  • Abdominal pain
  • Weight loss (Inadequate absorption  Anaemic).
  • Tiredness/lethargy
  • Diarrhoea
  • Abdominal mass
40
Q

What extra-intestinal manifestations are linked with IBD?

A

Arthritis
• Axial- Ankylosing spondylitis
• Peripheral

Skin
• Erythema nodosum
• Pyoderma gangrenosum

Eyes
• Anterior uveitis
• Episcleritis/iritis

Liver
• Primary sclerosing cholangitis (PSC) – Inflammation and scarring of the bile ducts.
• Autoimmune hepatitis

41
Q

Which genes lead to a genetic predisposition of IBD?

A

NOD2
HLA
ATG
IL23-R

42
Q

Which specific auto-antibodies are concerned with Crohn’s disease?

A

ASCA

43
Q

Which specific auto-antibodies are associated with ulcerative colitis?

A

pANCA

44
Q

Which bacteria has a possible relationship with IBD?

A

Mycobacterium paratuberculosis

45
Q

What is dysbiosis?

A

: In Crohn’s disease there is dysbiosis, as the gut microbiota is disrupted – lipopolysaccharides enter into systemic circulation.
• Loss of peripheral tolerance.

46
Q

What are the three management strategies for the treatment of IBD?

A
  1. Induce clinical remission
  2. Maintain clinical remission  Decrease hospitalisation/surgery & overall cost.
  3. Improve quality of life.
47
Q

What is the first line of treatment for IBD?

A

Short-acting steroids (as a bridge to other interventions + used in acute unwell patients).

48
Q

How do steroids work in IBD?

A

Diffuse into the nucleus, and bind onto glucocorticoid responsive elements (GRE)

GRE interacts with specific DNA sequences

Increase expression anti-inflammatory gene products

Block pro-infammatory genes

49
Q

Which immunmodulators are used in the treatment of IBD?

A

Azathioprine

Methotrexate and folic acid

50
Q

What is the mechanism of immunomodulators?

A

Immunomodulators help induce remission in active CD, downregulating DNA & RNA synthesis (causing cell proliferation to arrest).

51
Q

What is the mechanism of action of Azathioprine?

A

6-TGN interferes with adenine and guanine ribonucleotide production, inhibiting DNA synthesis within B- and T-lymphocytes (apoptosis of WBCs)

Decreased Ig and IL production

52
Q

Which ribonucleotides are affected by 6-TGN in azathioprine?

A

Adenine and guanine

53
Q

What type of drug is azathioprine?

A

Prodrug (That is activated into TGNs)

54
Q

What is the active metabolite of azathioprine?

A

6-TGN

55
Q

Which enzyme inactivates TGNs?

A

Thiopurine methyltransferase (TPMT)

56
Q

What is the risk in individuals with reduced activity of TPMT?

A

Thus, individuals with reduced activity of TMPT are exposed to higher levels of thioguanine – high risk of toxicity (including myelosuppression).
-Reduce dose in those with low TPMT.

57
Q

What are the side effects associated with azathioprine?

A
  • Bone marrow suppression
  • Lymphoma
  • Pancreatitis
  • Infection
  • Nodular regenerative hyperplasia/hepatotoxicity
  • GI-disturbances
  • Allergic reaction: Fever, rash, arthralgias, myalgias, fatigue.
58
Q

What is the mechanism of action of methotrexate?

A

Interferes with DNA synthesis and reproduction

  • Increased adenosine levels (anti-inflammatory)
  • Increased apoptosis of peripheral T cells
59
Q

What are the side effects associated with methotrexate?

A
•	Rash
•	Nausea, mucositis, diarrhoea
•	Bone marrow suppression 
•	Hypersensitivity pneumonitis 
•	Increased liver enzymes 
•	Hepatic fibrosis/cirrhosis
•	Abortifacient 
N.B: There is no documented increased risk of lymphoma or skin cancer.
60
Q

What is the mechanism of 5 ASA?

A

• Inhibition of lipo-oxygenase pathway (Prostaglandin and leukotrienes).
• Inhibition of pro-inflammatory cytokines (IL-1 and TNF-alpha).
• Scavenging of free radicals
• Inhibition of NF-kB/TLR via PPAR-gamma induction (peroxisome proliferator activated receptor-gamma).
N.B: Expresses immunosuppressive activity through inhibiting T-cell proliferation and differentiation. In addition to impairing neutrophil chemotaxis and activation.

61
Q

Which pro-inflammatory cytokines are inhibited by 5 ASA?

A

IL-1 and TNF-alpha

62
Q

Which pathway is inhibited by 5 ASA?

A

• Inhibition of lipo-oxygenase pathway (Prostaglandin and leukotrienes).

63
Q

How is 5 ASA delivered?

A

Mode of delivery: Orally & Rectal

64
Q

What are the side effects with using 5 ASA?

A
  • Diarrhoea
  • Renal impairment
  • Headache
  • Malaise
  • Pancreatitis
  • Pneumonitis
  • Intolerance
65
Q

How do biologics work?

A

Anti TNF-alpha

Infliximab and adalimumab

66
Q

What is infliximab?

A

A biologic - anti-TNF alpha

67
Q

How is Infliximab administered?

A

IV infliximab  8 weekly maintenance, induction 0,2,6 weeks, in hospital – less frequent.

68
Q

What is the effect of TNF-alpha on macrophages?

A

Increased release of pro-inflammatory cytokines and chemokines

69
Q

What is the effect of TNF-alpha on the endothelium?

A

Increased expression of adhesion molecules (increased cell infiltration)

70
Q

What is the effect of TNF-alpha on fibroblasts?

A

Increased acute phase response and metalloproteinase synthesis

Decreased collagen production (Tissue remodelling)

Increased CRP in serum

71
Q

What is the effect of TNF-alpha on the epithelium?

A

Increased ion transport
Increased permeability

This compromises barrier function

72
Q

What are the side effects with using biologics in IBD?

A
vSide effects: 
•	Opportunistic infections
•	Infusion or site reactions
•	Infusion reactions
•	Neutropenia
•	Infections
•	Demyelinating disease
•	Heart failure (HF)
•	Cutaneous reactions, including psoriasis
•	Malignancy
•	Induction of autoimmunity
73
Q

Which two drugs are used as a combination therapy in the treatment of IBD?

A

AZA/6MP and an anti-TNFA work synergistically, thus combination therapy improves patient outcomes and recovery.
• Reduces the rate of antibody formation.