营养性维生素D缺乏性佝偻病ppt课件

ix to fetus)? 食物中的维生素D? 天然食物(Most foods of infants contain small amounts of vitamin D)? 强化维生素D的食物(Foods are fortified with vitamin D)? 皮肤的光照合成(Skin’s exposure to ultraviolet irradiation)**? 皮肤7-脱氢胆骨化醇Р胆骨化醇VitD3?(内源性)Р紫外线Р维生素D的体内活化РVitDР25-(OH)D3 *Р1,25-(OH)2D3**Р25-羟化酶(肝脏)Р1-a羟化酶(肾脏)Р维生素D代谢的调节Р肝Р肾Р1,25-(OH)2D3Р低血磷Р高血磷Р甲状旁腺素Р降钙素Р低血钙Р(+)Р(+)Р(+)Р(-)Р(-)РVitDР25-(OH)D3Р高血钙Р(+)Р(-)Р自?身?反?馈Р促进小肠粘膜对钙磷的吸收? 增加肾小管对钙磷的重吸收? 促进破骨细胞成熟,旧骨中钙盐释放入血;刺激成骨细胞促进骨样组织成熟和钙盐沉积Р1,25-(OH)2D3的生理功能Р病因 EtiologyР围生期维生素D不足Inadequate store in perinatal stage ?日照不足** Inadequate exposure to sunlight ?维生素D摄入不足Inadequate intake of vitamin D ?生长速度快Rapid growth ?疾病与药物影响Influence by disease and drugР机制 MechanismРVitD缺乏Р吸收钙、磷减少Р血钙降低Р甲状旁腺Р肾小管重吸收?磷减少尿磷增加РPTH分泌不足Р低血磷Р破骨细胞作用加强Р血钙不能恢复正常Р细胞外液钙磷?沉积降低Р骨重吸收增加Р手足搐搦症Р钙正常或偏低Р骨矿化受阻Р佝偻病РPTH分泌增加