4 main layers of intestine
1) Serosa
2) Muscularis externa (composed of longitudinal and circular muscle)
3) Submucosa
4) Mucosa (composed of epithelium, lamina propria, and muscularis mucosa)
Fx of submucosa
The submucosa is the layer of dense irregular connective tissue or loose connective tissue that supports the mucosa, as well as joins the mucosa to the bulk of underlying smooth muscle.
Fx of mucosa
The mucosa is the innermost tissue layer of the small intestines, and is a mucous membrane that secretes digestive enzymes and hormones. The intestinal villi are part of the mucosa.
Review structural organization of alimentary canal
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What is diverticular disease?
How does its incidence relate to age?
Etiology/risks for diverticular disease?
1) Poor DIET (low fibre) → constipation causes accumulation in lumen, pressure on lumen increases (which has already been weakened by process of aging), causing out-pouchings
2) With AGE, diet becomes imbalanced because of changed dentition, cannot be hard things, degenerative changes of tissue
3) INACTIVITY – activity enhances perfusion of GI tract
4) POOR BOWEL HABITS (constipation) – does not as regularly evacuate bowels will contribute to constipation
Patho of Diverticular Disease
Where (in the GI tract) do the out-pouchings in diverticular disease usually occur? Just one or multiple?
Mostly within sigmoid colon (but can occur in most places in digestive tract) – mostly in large intestine because this is where problem of constipation is
• Multiple sites (usually have several outpouchings…not one single)
2 types of diverticular disease?
1) Diverticulosis
2) Diverticulitis
Difference between two types of diverticular disease?
1) Diverticulosis = non-inflamed out-pouchings (d/t injury or infection)
- Asymptomatic
2) Diverticulitis = inflamed out-pouchings
- Symptomatic
Symptoms of diverticulitis?
o Dull pain, nausea, vomiting, low grade fever
o Aching type of pain
Tx of diverticular disease?
* Address complications → sx for obstruction or perforation
Why does fever occur in absence of infection?
Damaged cells produce endogenous pyrogens
rest of mechanism is the same
What is IBS?
What is the problem?
Etiology of IBS?
* Linked to diet, stress, smoking, lactose intolerance
Why is smoking associated with IBS?
Smoking has series of noxious components that circulate within body, can cause intestinal cancers, etc….
What is thought to be the pathology of IBS?
Patho not apparent but are speculated ideas:
1) Malabsorption of fermentable CHO and polyols- suggests we have fermentable CHOs (ex: fructose) and polyols (sugar alcohols, ex: sorbitol) then when ingested by those with IBS, are not properly processed (in small intestine or stomach?) - in colon the bacteria process these sugars and produced gas → end up with flatulence → Gas distends the intestine, presents with pain
2) Altered CNS regulation of GI motor and sensory fx?
know CNS innervates digestive tract and is largely involved in regulating motility of the gut (also perfusion, secretion, etc.)…suggestion of theory is that there’s a problem either in CNS or where neurons meet digestive tract (such as synapse) that effects
3) Molecular signaling defect of serotonin
(is produced in mucosa of gut…thought that process of synthesis, release, storage, action, and/or degredation is defective
Functions of Serotonin:
1) Mediates motility in the gut
2) Involved in sensation/pain
3) Involved in secretion
4) Involved in perfusion (vasodilation/constriction)
What main pieces of evidence show that a seronin defect may be involved in IBS?
1) Site of synthesis - produced in mucosa
2) Serotonin action & IBS manifestations
- Fxs of serotonin very much linked to symptoms of IBS
- If serotonin is functioning normally, should not feel sensation/pain of peristalsis…IBS do
Symptoms of IBS
Dx of IBS?
• Problem because no obvious pathology
• Work through process of exclusion (excluding organic disease…such as infection of the gut, which would present with very similar symptoms)
o Various labs (cbc, stool exam looking for ova of parasites, likely barium swallow [to see structural defects such as ulcers]
• Scopes: endoscopy, colonoscopy
• Presentation: what food causes it, how it presents
What prep does endoscopy and colonoscopy require?
- prep for colonoscopy is over 2 days, need clean lower bowel)
Tx of IBS?
• Very difficult • Based on severity and type • Avoid offending foods • Reduce stress • Drugs (if moderate to severe) --> Often have sposmatic pain → antispasmodics prn (reduce motility), ex: modulon --> Antidiarrheals ---> Constipation drugs ---> Antibiotics used with caution → to maintain normal flora in check
What is peritonitis?
What is the peritoneum?
Inflm of peritoneum
The peritoneum is a membrane made up of two layers. One layer lines the cavity and the other layer lines the organs. The peritoneum helps support the organs in the abdominal cavity and also allows nerves, blood vessels, and lymph vessels to pass through to the organs. The parietal peritoneum lines the abdominal wall and extends to the organs, whereas the visceral peritoneum covers the organs. The peritoneal cavity lies between these two peritoneal layers. It contains a thin layer of fluid that lubricates the peritoneal surfaces.