Sandbox cerebral palsy: Difference between revisions
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*The bicarbonate ions act to neutralize harsh acids. | *The bicarbonate ions act to neutralize harsh acids. | ||
*If the balance of gastric acid secretion and mucosal defenses is disrupted, acid interacts with the epithelium to cause damage | *If the balance of gastric acid secretion and mucosal defenses is disrupted, acid interacts with the epithelium to cause damage | ||
===Pathogenesis=== | |||
*Regardless of etiology, if the balance of gastric acid secretion and mucosal defenses is disrupted, acid interacts with the epithelium to cause damage. | |||
**Helicobacter pylori disrupts the mucosal barrier and causes inflammation of the mucosa of the stomach and duodenum. | |||
**As the ulcer progresses beyond the mucosa to the submucosa the inflammation causes weakening and necrosis of arterial walls, leading to pseudoaneurysm formation followed by rupture and hemorrhage. | |||
**NSAIDs inhibit cyclooxygenase, leading to impaired mucosal defenses by decreasing mucosal prostaglandin synthesis. | |||
**During stress, there is acid hypersecretion; therefore, the breakdown of mucosal defenses leads to injury of the mucosa and subsequent bleeding. | |||
**Mucosal defects along with dilated and tortuous vessels in dieulafoy lesion put them at risk for rupture because of necrosis of the arterial wall from exposure to gastric acid. | |||
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{{familytree | | | | | | | | | | A01 | | | | | |A01=Inhibits cycloxygenase pathway}} | |||
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{{familytree | C01 | | C02 | | C03 | | C04 | | | | | C05 | |C01=Reduced<br>mucosal blood flow|C02=Reduced<br> mucosal and<br> bicarbonate secreation|C03=Impaired<br>platelet aggregation|C04=Reduced<br>angiogenesis|C05=Increased<br>leucocyte adherence|}} | |||
{{familytree | |!| | | |!| | | |!| | | |!| | | | | | |!| | | }} | |||
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{{familytree | | | | | | | | | E01 | | | | | | | | | | | | |E01=Impaired defence<br>Impaired healing}} | |||
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{{familytree | | | | | | | | | F01 | | | | | | | | | | | | |F01=Mucosal Injury}} | |||
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Revision as of 18:23, 26 October 2017
Pathophysiology
Mucosal barrier
- The gastric mucosa is protected from the acidic environment by mucus, bicarbonate, prostaglandins, and blood flow.
- This mucosal barrier consists of three protective components which include:
- Layer of epithelial cells lining.
- Layer of mucus, secreted by surface epithelial cells and Foveolar cells.
- Bicarbonate ions, secreted by the surface epithelial cells.
Mechanism of Action
- The insoluble mucus forms a protective gel-like coating over the entire surface of the gastric mucosa.
- The mucus protects the gastric mucosa from autodigestion by e.g. pepsin and from erosion by acids and other caustic materials that are ingested.
- The bicarbonate ions act to neutralize harsh acids.
- If the balance of gastric acid secretion and mucosal defenses is disrupted, acid interacts with the epithelium to cause damage
Pathogenesis
- Regardless of etiology, if the balance of gastric acid secretion and mucosal defenses is disrupted, acid interacts with the epithelium to cause damage.
- Helicobacter pylori disrupts the mucosal barrier and causes inflammation of the mucosa of the stomach and duodenum.
- As the ulcer progresses beyond the mucosa to the submucosa the inflammation causes weakening and necrosis of arterial walls, leading to pseudoaneurysm formation followed by rupture and hemorrhage.
- NSAIDs inhibit cyclooxygenase, leading to impaired mucosal defenses by decreasing mucosal prostaglandin synthesis.
- During stress, there is acid hypersecretion; therefore, the breakdown of mucosal defenses leads to injury of the mucosa and subsequent bleeding.
- Mucosal defects along with dilated and tortuous vessels in dieulafoy lesion put them at risk for rupture because of necrosis of the arterial wall from exposure to gastric acid.
| NSAIDS | |||||||||||||||||||||||||||||||||||||||||||||||
| Inhibits cycloxygenase pathway | |||||||||||||||||||||||||||||||||||||||||||||||
| COX-1 | COX-2 | ||||||||||||||||||||||||||||||||||||||||||||||
| Reduced mucosal blood flow | Reduced mucosal and bicarbonate secreation | Impaired platelet aggregation | Reduced angiogenesis | Increased leucocyte adherence | |||||||||||||||||||||||||||||||||||||||||||
| Impaired defence Impaired healing | |||||||||||||||||||||||||||||||||||||||||||||||
| Mucosal Injury | |||||||||||||||||||||||||||||||||||||||||||||||