眼科学基础：眼生物化学细胞生物学.pdfVIP

七年制眼视光专业《眼科学基础》之 Biochemistry and Cell Biology Introduction  Biochemistry and Cell Biology  The rich variety of biochemical processes that occur within the eye encompasses many aspects of general physicochemical reactions Cornea  Functions Protection Refraction  Corneal transparency is a function of its normal biochemical reactions Cornea  Protein: 18%~20%  Soluble protein • Determination of antigen • Transparency of graft  Collagen: 15% • 75% dry weight • Type I, secreted by keratocyte • Type VII, composed anchoring fibres Cornea Cornea  Collagen in stroma  Type I • Main type • Fibrillar  Type V • Fibrillar • More complex than type I • Adjustable diameter • Transparency  Type VI • Nonfibrillar • Regulate interaction in extracell matrix Cornea Cornea  Glycosaminoglycan (GAG, 粘多糖) Keratin sulphate (硫酸角蛋白) 50%  Chondroitin (软骨素) 25%  Chondroitin sulphate (硫酸软骨素) 25%  Corneal edema and hazy Cornea  Proteoglycan  GAGs bound to core proteins Native state of corneal GAGs Oxygen handling by the cornea  Epithelium From the preocular tear film  Endothelium and the keratocytes in the deep stroma From the circulation via the aqueous humour  Limbus and palpebral conjunctiva Glucose metabolism  In the absence of oxygen  Glycolysis converts glucose to pyruvate 2 ATP  In the presence of oxygen  The citric acid cycle 36