Lower GI Tract Flashcards
What nerve innervates the ascending colon and most of the transverse colon in terms of parasympathetic supply?
Vagus nerve
What is distal parasympathetic supply from?
Pelvic nerves
What nerves give sympathetic supply to the lower GI tract
Lower thoracic and upper lumbar spinal cord
What is the external anal sphincter controlled by?
Somatic motor fibres in the pudendal nerves
What disease occurs when theres no enteric nervous system?
Hirschsprung’s
Where is the myenteric plexus ganglia concentrated?
Below the tenia coli
What are the 4 layers of the colon
Mucosa
Submucosa
Muscularis (made of 2 layers circular and longitudinal layers)
Serosa
Where does nerve supply to the lower GI tract come from?
Centrally AND from the submucosal and myenteric plexus (they are like localised pacemakers)
What does the mucosa layer contain? Why is this useful?
Lots of mucin producing glands to allow easy passage of stool and lubrications
What are the inflammatory lower GI tract disorders?
IBD and microscopic colitis
What are the infective lower GI tract disorders?
C diff
E coli
What are the structural lower GI tract disorders?
Diverticular disease
Haemorrhoids
Fissures
What are the functional lower GI tract disorders?
Irritable bowel syndrome
What are the neoplastic lower GI tract disorders?
Colonic polyps
Colon cancer
Who does IBD often affect?
Young people
What type of condition is IBD?
Lifelong, chronic and autoimmune
What is ulcerative colitis?
Inflammatory disorder limited to the colonic mucosa
What is the pattern of inflammation in UC?
Continuous
What anatomical area is always involved in UC?
Rectum
Does UC affect males or females more?
Effects both equally
What is NOT present in UC?
Granulomas
What anatomical area does Crohn’s effect?
Any part of the GI tract
What is the pattern of inflammation in Crohn’s?
Patchy chronic transmural granulomatous inflammation
What structures may be formed in Crohn’s and why?
Tendency to form fistula (penetration between 2 walls) or strictures (narrowing of the lumen, there is non expansive fibrous tissue). They form because deeper layers are affected in Crohn’s compared to UC
Out of UC and Crohn’s which are painful and why?
Crohn’s is more
Generally UC is not
This is because deeper areas are affected in Crohn’s
What do IBD symptoms depend on?
Site of bleeding
What symptoms will colitis present with?
Bleeding
Mucus
Urgency
Diarrhoea
What symptoms will perianal areas being affected present with?
Anal pain
Leakage
Difficulty passing stool
What symptoms will small bowel disease present with?
Abdominal pain Weight loss (due to less absorption) Tiredness/lethargy (less absorption causes anaemia) Diarrhoea Abdominal mass
What are some extra intestinal manifestations of IBD?
Arthritis (axial – Ankylosing spondylitis) Peripheral Skin (Erythema nodosum Pyoderma gangrenosum Eyes (Anterior uveitis Episcleritis/Iritis) Liver (Primary Sclerosing Cholangitis (PSC) Autoimmune hepatitis)
What are the 3 biggest influencers in the development of IBD?
Environmental factors like luminal microbes
Genetic susceptibility
Immune response
What does immune response in Crohn’s involve?
Anti-saccaromyces cervisiae (ASCA)
What does immune response in UC involve?
pANCA
In terms of urination/bowel movements what does urgency mean?
You have control but you have to go
In terms of urination/bowel movements what does incontinence mean?
You don’t have control over what you pass and when
What IBD is perianal disease associated with?
Crohn’s only
Why do strictures and fistulations form in Crohn’s?
Due to deeper areas being affected whereas UC is superficial
Define dysbiosis
Microbial imbalance or impaired microbiota
What does poor bacterial community in the microbiota cause?
Inflammation
What are the 3 main goals when treating IBD?
Induce clinical remission
Maintain clinical remission
Improve patient quality of life
What is the main action of steroids for IBD?
Diffuses and bind in nucleus to Glucocorticoid Responsive Elements (GRE) which increases anti-inflammatory gene products blocks pro-inflammatory genes
How are steroids for IBD administered?
IV, oral or rectal enema
How long can steroids be used? Why?
Only short term for acutely unwell patients as they cause lots of side effects and become less effective long term
What is the main action of 5 ASA for IBD?
Reduces inflammation via methods such as
Inhibition of pro-inflammatory cytokines (IL-1 and TNF-a )
Inhibition of the lipo-oxygenase pathway i.e. prostaglandin and leukotrienes
Scavenging of free radicals
What is the main action of azathioprine for IBD?
Results in reduced number of B and T lymphocytes, immunoglobulins and interleukins with the overall aim of reducing inflammation
What things do we need to monitor/check when giving immunosupressants?
Thiopurine TPMT Hep B/C HIV Chickenpox If they gave had all their vaccinations TB Frequently check bloods when starting and also regularly afterwards
What are some side effects of biologic therapies?
Opportunistic infections Infusion or site reactions Neutropenia Demyelinating disease Heart failure (HF) Cutaneous reactions, including psoriasis Malignancy Induction of autoimmunity
