生物转运与生物转化.ppt

卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * 卫生毒理学 * Toxicology - Chaper 3 * Transportation and Transformation of Xenobiotics Chapter 3 Toxicology - Chaper 3 * Absorption Section 1 Toxicology - Chaper 3 * Cell Membranes A phopholipid bilayer with polar head groups on both surfaces. Proteins or glycoproteins are inserted in or across the bilayer. The fluid character of membranes is determined largely by the structure and relative abundance of unsaturated fatty acids. Toxicology - Chaper 3 * Transport Passive transport: simple diffusion; filtration Special transport: active transport; facilitated diffusion; additional transport processes: phagocytosis and pinocytosis Toxicology - Chaper 3 * Absorption Absorption: Transfer of a chemical from the site of exposure into the systemic circulation by cross body membranes. The main sites of absorption are the GI tract, lung and skin, but there are other ways of administration including enteral and parenteral routes. Toxicology - Chaper 3 * Factors altering the GI absorption of toxicants pH of the GI Residency time of compounds Physical properties of chemicals First-pass effect Food: ion, milk Toxicology - Chaper 3 * Factors altering the lung absorption of toxicants Gases and vapors Blood-to-gas partition-coefficient Aerosols and particles Solubility Size: 2-5μmainly deposited in the tracheobronchium Toxicology - Chaper 3 * Factors altering the skin absorption of toxicants Molecular weight Lipid/water solubility Condition of the skin Cutaneous blood flow Solvents Toxicology - Chaper 3 * Distribution and Excretion Section 2 Toxicology - Chaper 3 * Distribution Plasma water Extracellular water Intracellular water Tissue binding Redistribution: organ affinity Toxicology - Chaper 3 * Storage of toxicant in tissues Plasma protein Liver and kidney Fat Bone Barrier: blood-brain, placenta Toxicology - Chaper 3 * Excretion Urinary excretion Fecal excretion Biliary excretion Intestina