协和基础医学院-肝胆生理(考试部分仅限于中文幻灯)

Excretory Functions:
The principal excretory product of the liver is bile, an aqueous mixture of
•conjugated bilirubin, •bile acids, phospholipids, •cholesterol •electrolytes. Bile not only provides a repository for the products of heme catabolism but is also vital for fat absorption in the small intestine.
• It performs an astonishingly large number of tasks that impact all body systems:
– catabolizing dietary amino acids , carbohydrates, lipids, and vitamins; – synthesizing and secreting serum proteins; – detoxifying the endogenous waste products and xenobiotics and
particularly with advancing age. Uninucleate,
Hepatic Parenchyma-2
• Between the cords of hepatocytes are vascular sinusoids. Blood traverses the sinusoids and exits into the terminal hepatic vein through orifices of vein wall. Hepatocytes are bathed on 2 sides by well-mixed portal venous and hepatic arterial blood.
• Portal tracts are at periphery of lobule • Hepatocytes present at
– Centrilobular around central vein (Hepatic – Periportal near the portal tract
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Hepatic Parenchyma-1
Micro architecture
• Classically, the liver has been divided into 1- to 2-mm diameter hexagonal lobules
• Lobule oriented around terminal hepatic veins tributaries
• Hepatocytes in the intermediate zone II and pericentral hepatocytes located near the terminal hepatic venule (zone III ) are exposed to progressively lower concentrations of nutrients and oxygen.
Liver- Functions
• Vascular functions, including formation of lymph and the hepatic phagocytic system.
• Metabolic achievements in control of synthesis and utilization of carbohydrates, lipids and proteins.
Periportal Hepatocytes Specialize In Oxidative Metabolism; Pericentral Hepatocytes Detoxify Drugs
• Periportal hepatocytes (zone I) are the most resistant to the effects of circulatory compromise, nutritional deficiency and other forms of cell injury and are the first to regenerate.
➢促脂肪消化：乳化脂肪、增加酶作用面积; ➢促脂肪吸收：与脂肪形成水溶性复合物; ➢促脂溶性维生素（A、D、E、K）吸收; ➢促胆汁的自身分泌：肠 - 肝循环。
The Secretion of Canalicular Bile Is Active and Isotonic
胆盐进入小肠后， 约 95% 被 回 肠 末 端 黏 膜吸收，通过门V又回 到肝脏，再成为合成胆 汁的原料，然后胆汁又 分泌入肠，这一过程称 为胆盐的肠肝循环。
glycogenolysis and gluconeogenesis.
Synthetic functions
Most serum proteins, including •Albumin •Blood coagulation factors •Complement, •Acute phase reactants • binding proteins for iron, copper, and vitamin A
excrete into bile. – secreting bile
• The liver is vulnerable to a wide variety of metabolic, toxic, microbial, and circulatory insults
• It has tremendous regeneration capacity
Plasma Proteins synthesized
Storage Functions
The liver is an important storage site for •Glycogen, •Triglycerides, •Iron, copper, •Lipid-soluble vitamins.
• Outgoing Blood- collected into ramifications of
the hepatic vein, which exits by the "back door" of the liver into the closely apposed inferior vena cava.
• The hepatic parenchyma is organized into cribiform (pierced with holes as in a sieve ), anastomosing sheets or "plates" of hepatocytes
• Hepatocytes immediately abutting the portal tract are referred to as the limiting plate, forming a rim around the mesenchyme of the portal tract.
• There is a radial orientation of the hepatocyte cords around the terminal hepatic vein.
• Hepatocytes exhibit variation in size, • Nuclei may vary in size, number, and ploidy,
• There are scattered fat-containing perisinusoidal stellate cells in the space of Disse. They stellate cells play a role in metabolism of vitamin A and are transformed into collagen-producing myofibroblasts in inflammation
肝胆生理
协和基础医学院生理系
二、胆汁 (bile)
（一）性质
➢ 浓稠、味苦、有色液体。 800～1000ml/day
➢ 肝胆汁—金黄色、枯棕 色，弱碱性，pH 7.4
➢ 胆囊胆汁—黄绿色、弱 酸性，pH 6.8
➢ 持续分泌、间歇排放，不 含消化酶。
（二）成分和作用
1. 胆盐 (bile salt)
Blood Supply
• Incoming blood-
• 25% of cardiac output—arrives via the Portal vein it is 60% to 70% of hepatic blood flow
• 30% to 40% from hepatic artery through the hilum, the "gateway" of the liver (porta hepatis).
• These blood vessels subdivide in the liver repeatedly, terminating in very small capillaries.
• Each capillary leads to a lobule.
Zonal Flow of Blood
1.神经调节
食物(蛋白分解产物＞脂肪酸＞糖) →条件与非条件反射（①纯神经机 制②迷走-促胃液素机制）→肝脏→ 胆汁分泌和排放。
2.体液调节 ① 缩胆囊素 ② 促胰液素 ③ 促胃液素 ④ 胆盐
Introduction