Physiology 206 Lecture 2 Outline of Last Lecture I. PhysiologyII. HomeostasisOutline of Current Lecture I. Cell PhysiologyII. Fluid in bodyIII. DiffusionIV. Facilitated DiffusionV. Active TransportCurrent Lecture- Cell physiology (under ‘general physiology’)-how messages are transmitted along nerves- Fluid in bodyo Intracellular fluid (ICF)-inside cellso Extracellular fluid (ECF)-outside cellsICF ECFK+ k+Na+ Na+- Simple diffusiono Random movement of molecules under the influence of heato Diffusion rate-net movement of some molecules across a barrier (membrane) Increased amount of molecules moving = increased diffusion rate Influenced by differences in concentrations on either side of the membrane The greater concentration difference the greater net movemento Size of molecules influences diffusion Small molecules diffuse at a greater rate, requires less energy to moveo Surface area influences diffusionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Greater area = greater diffusion rateo Length of diffusion path influences diffusion Greater length = decreased diffusiono Viscosity-resistance of liquid to flow Greater viscosity = decreased diffusion Water has a high viscosityo Temperature influences diffusion Increased temperature = increased diffusion (more rapid diffusion) We usually have very little temperature change in our bodiesDiffusion Rate = concentration difference x surface area x temperatureMolecule size x length x viscosityo Sodium and potassium can both diffuse across membranes- Facilitated Diffusiono Mechanism for providing a pathway across a membrane that a cell wouldn’t otherwise haveo Membranes have layers of lipids and aqueous channelso Molecules that are lipid soluble can dissolve right through the lipidso Water soluble molecules (small) can go through aqueous poreso Specific proteins (carrier proteins) are embedded in lipid membrane Parts of proteins flip flop back and forth to transport molecules across the membrane Reversibly bind and release molecules- Where concentration of molecules is high, they bind more moleculeso No energy required!- Active transporto Requires energy input to occuro ATP --> ADP + energyo ATPase-enzyme, coverts ATP to ADP with the release of energyo Also called a sodium pump; Na, P, ATPase pump Located in membrane Uses ATP to pump potassium in (diffuses out) and sodium out (diffuses
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