mouth (口), esophagus (食道), and stomach (胃).pdf

Exocrine pancreas (旁分泌胰臟) and Liver (肝臟) Overview The pancreas, gallbladder, and liver serve as accessory organs for the intestines, providing specialized secretions to digest carbohydrates, proteins, and lipids in the small intestine. Pancreatic secretions are highly regulated by neural and hormonal means both in anticipation of eating and in response to food in the gastrointestinal tract. Hepatobiliary secretions are steadily produced but then stored in the gallbladder for regulated secretion into the small intestine. Once digested and absorbed, most nutrients travel via the portal circulation to the liver to either be extracted and processed or to pass through to the systemic circulation. 旁分泌胰臟的分泌作用 (exocrine pancreatic secretions) 胰腺的囊泡細胞(acinar cell)分泌酶 原型式的消化酶及胰蛋白酶抑制劑, 可避免酶過早活化而破壞胰組織 導管細胞分泌含碳酸根離子(HCO3-) 及水份的鹼性消化液, HCO3- 能中和 胃酸, 保護十二指腸黏膜 主要的胰消化酶 胰澱粉酶(pancreatic amylase): - 將唾液澱粉酶未消化的澱粉、肝醣以 及大部份的醣類分解成雙醣類及少許的 三醣類, 如麥芽糖、麥芽三糖及α-糊精 等物質 胰脂肪酶(pancreatic lipase): - 將送入十二指腸的三酸甘油酯水解成 脂肪酸和單酸甘油酯 胰蛋白酶(trypsin): - 須先由腸激活酶(enterokinase) 活化,才具分解蛋白質的功能 胰凝乳蛋白酶(chymotrypsin): - 先由胰蛋白酶活化, 才具分解蛋 白質的功能 胰分泌的調節(regulation of pancreatic secretions 迷走神經: - 在胃液分泌的頭期,食糜尚未進入十二 指腸前,迷走神經即可刺激囊泡細胞分泌 大量的胰消化酶 胰泌素(secretin): - 酸性食糜可刺激十二指腸分泌胰泌素, - 胰泌素可促進鹼性胰消化液的分泌 膽囊收縮素(cholecystokinin; CCK): - 蛋白質消化產物(如: 生太、氨基酸 等及脂肪酸)可刺激十二指腸分泌 CCK, - CCK 促進胰消化酶的分泌, - 並刺激腸激酶(enterokinase)的分 泌, - 腸激酶可將胰蛋白酶原活化轉為胰 蛋白酶 肝臟膽汁的分泌(hepatobiliary secretion) 膽汁(bile)由肝臟細胞所製造分泌, - 其中含有水、鹽類及脂肪類物質, - 膽鹽為膽汁中含量最多的一種物質, - 膽鹽參與脂肪的消化與吸收, - 約97% 膽鹽可於迴腸再吸收, - 經由肝腸循環重返肝臟 膽汁呈黃褐色或橄欖綠, - pH值為7.6-8.6, - 膽紅素(bilirubin)為主要之膽色 素, - 由血紅素之基質代謝而來, - 膽紅素在腸內被轉變為尿膽素 (urobilinogen), 與糞便顏色有關 肝細胞每天分泌800-1000 ml 膽汁, -