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→Intrinsic protective factors
====Intrinsic protective factors====
====Intrinsic protective factors====
=====Glandular mucosal defence mechanisms<ref name="EGUC">The Equine Gastric Ulcer Council (1999) Tutorial Article: Recommendations for the diagnosis and treatment of equine gastric ulcer syndrome (EGUS). ''Equine Vet Educ'', 11(5):262-272.</ref>=====
=====Glandular mucosal defence mechanisms<ref name="EGUC">The Equine Gastric Ulcer Council (1999) Tutorial Article: Recommendations for the diagnosis and treatment of equine gastric ulcer syndrome (EGUS). ''Equine Vet Educ'', 11(5):262-272.</ref>=====
*'''Mucus:''' secreted by specialised mucous neck cells. A viscous, hydrophobic glycoproteinaceous gel that adheres to the mucosa and resists acid and pepsin contact. Also acts as a lubricant to minimise mechanical damage.
*'''Mucus:''' secreted by specialised mucous neck cells. This viscous, hydrophobic glycoproteinaceous gel adheres to the mucosa and resists acid and pepsin contact. Also acts as a lubricant to minimise mechanical damage.
*'''Bicarbonate:''' secreted by gastric mucosal cells. Secretion triggered by luminal acid concentrations, mechanical irritation, and release of endogenous prostaglandins. Bicarbonate trapped in the mucous layer forms a pH gradient allowing a physiological pH at the mucosal surface and a gastric acid pH at the luminal surface.
*'''Bicarbonate:''' secreted by gastric mucosal cells. Secretion triggered by luminal acid concentrations, mechanical irritation, and release of endogenous prostaglandins. Bicarbonate trapped in the mucous layer creates a pH gradient from physiological pH at the mucosal surface to a gastric acid pH at the luminal interface.
*'''Epidermal growth factors:''' found in salivary gland secretions, promote DNA synthesis and proliferation of gastric mucosal cells. Also play a role in prostaglandin synthesis and inhibit HCl secretion by the parietal glands.
*'''Epidermal growth factors:''' found in salivary gland secretions, promote DNA synthesis and proliferation of gastric mucosal cells. Also important in prostaglandin synthesis and inhibit hydrochloric (HCl) secretion by the parietal glands.
*'''Epithelial restitution mechanisms:''' important in the maintenance of gastric mucosal integrity (maintain tight junctions). Epithelial injury induces migration of adjacent cells to replace damaged cells within minutes without the need of new cell proliferation. Shear forces, induced by mixing of ingested material, are counteracted by epithlial restoration.
*'''Epithelial restitution mechanisms:''' important for gastric mucosal integrity. Epithelial injury induces migration of adjacent cells to replace damaged cells within minutes without the need of new cell proliferation. Shear forces, induced by mixing of ingesta, are counterbalanced by epithlial restoration.
*'''Adequate mucosal blood supply:''' required to provide the mucosa with oxygen and nutrients to produce the mucus-bicarbonate layer and to support rapid turnover of epithelial cells. Also required to remove acid that has diffused through the mucous layer to the mucosa. Mucosal perfusion may be important in the stress-related ulceration of neonates.<ref name="Sanchez">Sanchez, L.C (2010) 'Diseases Of The Stomach' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Saunders, Chapter 15.</ref>
*'''Adequate mucosal blood supply:''' required to provide the mucosa with oxygen and nutrients to produce the mucus-bicarbonate layer and to support rapid turnover of epithelial cells. Also required to remove acid that has diffused into the mucosa. Compromised mucosal perfusion may be important in the stress-related ulceration of neonates.<ref name="Sanchez">Sanchez, L.C (2010) 'Diseases Of The Stomach' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Saunders, Chapter 15.</ref>
*'''Prostaglandins:''' inhibit acid secretion, promote mucosal blood flow (through vasodilation), increase mucus and bicarbonate secretions and support mucosal cell repair. PGE2 is especially important in these functions.
*'''Prostaglandins:''' inhibit acid secretion, promote mucosal perfusion (through vasodilation), increase mucus and bicarbonate secretions and support mucosal cell repair. PGE2 is especially important in these functions.
=====Squamous mucosal defence mechanisms<ref name="EGUC">The Equine Gastric Ulcer Council (1999) Tutorial Article: Recommendations for the diagnosis and treatment of equine gastric ulcer syndrome (EGUS). ''Equine Vet Educ'', 11(5):262-272.</ref>=====
=====Squamous mucosal defence mechanisms<ref name="EGUC">The Equine Gastric Ulcer Council (1999) Tutorial Article: Recommendations for the diagnosis and treatment of equine gastric ulcer syndrome (EGUS). ''Equine Vet Educ'', 11(5):262-272.</ref>=====
The squamous mucosa has comparatively few defence mechansims:
The squamous mucosa has comparatively few defence mechansims:
*'''Intercellular tight junctions''' and '''intracellular buffering systems''' act as barriers
*'''Intercellular tight junctions''' and '''intracellular buffering systems''' act as barriers
*'''Epidermal growth factor''' has also been found to contribute to the healthy maintenance and repair of gastric squamous epithelium.<ref>Jeffrery, S.C, Murray, M.J, Eichorn, E.S (2001) Distribution of epidermal growth factor receptor (EGFr) in normal and acute peptic-injured equine gastric squaous epithelium. ''Equine Vet J'', 33:562-569. In: Martineau, H, Thompson, H, Taylor, D (2009) Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. ''Equine Vet J'', 41(7):638-644.</ref>
*'''Epidermal growth factor''' also contributes to the maintenance and repair of gastric squamous epithelium.<ref>Jeffrery, S.C, Murray, M.J, Eichorn, E.S (2001) Distribution of epidermal growth factor receptor (EGFr) in normal and acute peptic-injured equine gastric squaous epithelium. ''Equine Vet J'', 33:562-569. In: Martineau, H, Thompson, H, Taylor, D (2009) Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. ''Equine Vet J'', 41(7):638-644.</ref>
=====Other intrinsic defence mechanisms=====
=====Other intrinsic defence mechanisms=====