生理学第二章细胞.ppt

Outline Part 1. Transport across cell membrane Part 2. Trans-membrane signal transduction Part 3. Cellular bioelectricity Part 4. Contraction of muscle cell Essential role of cell membrane: Action of outpost Exchange of material Accept signal Distinguish mark Programming reactions 3. Active transport Characteristics of the Transport by Na+ pump Directional transport Coupling process ATP is directly required Electrogenic process Importance of the Na+-K+ Pump Maintain high intracellular K+ concentration gradients across the membrane. Control cell volume and phase Maintain normal pH inside cell Develop and Maintain Na+ and K+ concentration gradients across the membrane Electrogenic action influences membrane potential Provides energy for secondary active transport Secondary Active Transport Coupled transport. Energy needed for “uphill” movement obtained from “downhill” transport of Na+. Hydrolysis of ATP by Na+/K+ pump required indirectly to maintain [Na+] gradient. 4.Bulk Transport (Endocytosis and Excytosis) Movement of many large molecules, that cannot be transported by carriers. Exocytosis: A process in which some large particles move from inside to outside of the cell by a specialized function of the cell membrane Endocytosis: Exocytosis in reverse. Specific molecules can be taken into the cell because of the interaction of the molecule and protein receptor. Part 2. Trans-membrane signal transduction Receptor-gated channel Receptor-GTP binding protein-effecter enzyme system: CA→cAMP; CG →cGMP; PLC →IP3,DG Tyrosine protein kinase (TPK) receptor Part 3.Cellular Bioelectricity 1.Conception about stimulus and excitability Excitation: an action potential occurs after a effective stimulus acting on cell. Excitability: cell’s ability to genesis action potential after being stimulated. Excitable cells: cells which are easy to genesis action potential under stimulus. Essential element of stimulus: intensity ,duration,changing rate. 11. Propagation of the Acti