1. TOPICS Review of major compartments/fluids Movement among compartments Review of Plasma Membrane permeability Passive Transport –Diffusion Simple diffusion Facilitated diffusion –Osmosis –Filtration Active Transport –Ion pumps –Secondary active transport –Endocytosis –exocytosis

2. Body-Fluid Compartments Intracellular (67% of total body fluids) Extracellular (33% of total body fluids) –blood plasma (6.6% of total body fluids) –interstitial fluid or tissue fluid (26.4% of total body fluids) 1-45 A B C

3. ECF ICF

4. Solution = solvent + solutes water non-water

5. Extracellular (outside cell) Intracellular (inside cell) Lipid bilayer Non-polar tail region Prevents passage of ions and polar molecules (except water) Water and lipid soluble substances pass through

6. 6

7. or channel Membrane permeability summary TransportproteinTransportprotein

8. TRANSPORT PROTIENS OF THE PLASMA MEMBRANE Have binding sites -- specific -- competition -- saturation -- facilitate diffusion Facilitated Diffusion Ion Pumps Always open -- ions -- some specificity facilitated diffusion Open and Close --ions -- some specificity -- condition specific facilitated diffusion

9. All matter is in motion  diffusion

10. Diffusion: movement (inherent in all chemicals) results in substances spreading from where they are more highly concentrated to where they are less concentrated Resulting in uniformly distributed substances that are still in motion (but evenly spread out)* *at least in the absence of other factors/influences

11. Diffusion Across a Membrane: Results in a net change in concentrations, but movement never stops  dynamic equilibrium

12. Diffusion Times Time it takes the “average” molecule to diffuse a given distance. DistanceTime 1 ųm0.5 msec 10 ųm50 msec 100 ųm5 sec 1 mm8.3 min 1 cm14 hr ųm = 1/1000 of a millimeter msec = 1/1000 of a second too slow; if a substance had to diffuse this distance the cell would die waiting for needed materials size range of “typical” cells and typical distance from a blood vessel

13. DIFFUSION RELATED TOPICS Random movement of all matter is why/how –substrates find/bind enzymes –chemical signals find/bind receptors Concentrations power the net movement of these substances onto and off of the chemicals they bind –Higher concentrations drive substances to bind receptors/enzymes –Low concentrations will drive substances off receports/enzymes (or at least slow binding) Concentration gradient influences rate of interactions

14. Fig. 6.2 Diffusion subtypes and classes of molecules transported Simple Diffusion Through lipids: nonpolar molecules—O2, CO2, fatty acids, steroid hormones Water Facilitated diffusion Through channel proteins: ions water (through aquaporins) Facilitated Diffusion through carrier proteins: e.g., glucose, amino acids

15. Example of Simple Diffusion through membrane lipids

16. Fig. 6.6 Gated Channels: open and close under different conditons/stimuli Ligand Gate, voltage gated, mechanically gated, etc….

17. Fig. 6.16 Facilitated Diffusion through a carrier protein

18. Different Carriers for different substances

20. expandsshrinks No change

21. Fig. 6.13

22. Issues in Osmosis: glycogen is the stored form of glucose diarrhea

23. glucose glycogen A B

24. Filtration pressure

25. Filtration: -- Size determines what passes through membrane --more pressure  more filtration

26. Fig. 6.18 Active Transport: ion pumps pump

27. Fig. 6.19 Active Transport: sodium/potassium pump (exchange)

29. Carrier-Mediated Transport : facilitate transport and primary active transport/pumps Protein carriers exhibit: –Specificity for specific (sometimes single) molecules NOTE: specificity can also be true of ion channels –Competition among compatible substrates for transport Competition reduces the transport rate of any single substance –Saturation when all carriers are occupied There is a maximum transport rate 6-24

30. Fig. 6.15 Saturation, competition, and maximum transport

32. Fig. 6.20 Cotransport/symport: Diffusion of one substance powers uphill movement of another

33. Fig. 6.20 Cotransport/symport: Diffusion of one substance powers uphill movement of another

39. Fig. 6.23

41. Receptor mediated endocytosis

42. Fig. 6.21