Physiology 206 Lecture 2 Outline of Last Lecture I Physiology II Homeostasis Outline of Current Lecture I Cell Physiology II Fluid in body III Diffusion IV Facilitated Diffusion V Active Transport Current Lecture Cell physiology under general physiology how messages are transmitted along nerves Fluid in body o Intracellular fluid ICF inside cells o Extracellular fluid ECF outside cells ICF ECF K k Na Na Simple diffusion o Random movement of molecules under the influence of heat o 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 movement o Size of molecules influences diffusion Small molecules diffuse at a greater rate requires less energy to move o Surface area influences diffusion These 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 o o o Greater area greater diffusion rate Length of diffusion path influences diffusion Greater length decreased diffusion Viscosity resistance of liquid to flow Greater viscosity decreased diffusion Water has a high viscosity Temperature influences diffusion Increased temperature increased diffusion more rapid diffusion We usually have very little temperature change in our bodies Diffusion Rate concentration difference x surface area x temperature Molecule size x length x viscosity o Sodium and potassium can both diffuse across membranes Facilitated Diffusion o Mechanism for providing a pathway across a membrane that a cell wouldn t otherwise have o Membranes have layers of lipids and aqueous channels o Molecules that are lipid soluble can dissolve right through the lipids o Water soluble molecules small can go through aqueous pores o 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 molecules o No energy required Active transport o Requires energy input to occur o ATP ADP energy o ATPase enzyme coverts ATP to ADP with the release of energy o Also called a sodium pump Na P ATPase pump Located in membrane Uses ATP to pump potassium in diffuses out and sodium out diffuses in
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