浙江大学医学院：细胞生理学 Cell Physiology（Anatomy & physiology of cells）

Anatomy physiology feely Huan ma(马欢),PhD Department of physiology Room 515. block c. Research building School of Medicine, Zijingang Campus Email:mah@zju.edu.cn Tel:88208068

Anatomy & physiology of cells Huan Ma（马欢），PhD Department of Physiology Room 515, Block C, Research Building School of Medicine, Zijingang Campus Email: mah@zju.edu.cn Tel: 88208068

Sectional view Figure 3-1 Anatomy and Physiology: From Science to Life 9 2006 John Wiley Sons

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Structure of cell membrane Fluid Mosaic Model(Singer Nicholson, 1972) Proteins Carbohydrate Lipids 6

Structure of cell membrane: Fluid Mosaic Model (Singer & Nicholson, 1972)

Compartment 1 Compartment 2 High solute concentration Low solute concentration One-way flux∴∴∴∵ One-way flux Net flux Note: the partition between the two com partments is a membrane that allows this solute to move through it. Net flux accounts for solute movements in both directions

Note: the partition between the two compartments is a membrane that allows this solute to move through it. Net flux accounts for solute movements in both directions

Simple Diffusion单纯扩散 Relative to the concentration gradient movement is down the concentration gradient ONLY (higher concentration to lower concentration) (outside) lipid- soluble molecules Rate of diffusion depends on O2, CO2, H2O The concentration gradient Charge on the molecule Size Lipid solubility 0888 ° Temperature (inside)

Simple Diffusion 单纯扩散 Relative to the concentration gradient movement is DOWN the concentration gradient ONLY (higher concentration to lower concentration) Rate of diffusion depends on • The concentration gradient • Charge on the molecule • Size • Lipid solubility • Temperature

In sim ple diffusion, flux rate is lim ited nly by the Copyright o The McGraw-Hill Companies, Inc. Permission required for reproduction or display concentration gradient Diffusion In carrier. mediated transport, the num ber Maximal flt LL of available carriers places an Mediated transport upper limit on the flux rate Extracellular solute concentration

In simple diffusion, flux rate is limited only by the concentration gradient. In carrier￾mediated transport, the number of available carriers places an upper limit on the flux rate

Outside Gate Na Na closed Gate open Characteristics of ion channels Inside 口 Specificity gAting Outside w Gate open Gate K closed K- Inside

Characteristics of ion channels ❑Specificity ❑Gating

Three types of passive, non-coupled transport through integral membrane proteins A PORE(NON-GATED CHANNEL) B CHANNEL (GATED PORE) J Channels are conduits that Pores are conduits are gated by a"door. that are always open 8 Channel is closed Channel is Extracellular Cytosol space

Three types of passive, non-coupled transport through integral membrane proteins

C CARRIER 2 The carrier is open X enters from outside and to the outside binds at a binding site Carriers are conduits that are ated by two 8 "doors that are never open at the same time. Binding site The outer gate closes and X becomes occluded, still attached to its binding site 6 The outer gate closes, occluding an empty cycle can also flow in reverse order 4 X exits and enters th The inner gate opens nside of the cell with X still bound

Low concentration High concentration 41024489:982:::0 8431130:185 In both simple and facilitated diffusion;∷∴…∴ solutes move in the direction predicted Diffusion by the concentration gradient , Facilitated diffusion Active transport In active transport, solutes move opposite to the direction predicted by the concentration gradient

In both simple and facilitated diffusion, solutes move in the direction predicted by the concentration gradient. In active transport, solutes move opposite to the direction predicted by the concentration gradient. membrane