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Weeks 1 and 2 Notes

Weeks 1 and 2 Notes - Diffussion Ion Pumps Resting...

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Diffussion, Ion Pumps Resting Potentials: Graded and Action Potentials I. Diffusion Exchange between intracellular and extracellular compartments is restricted by cell membrane. Selectively permeable: lipid and protein composition of cell membrane determines which molecules enter/leave Impermeable: doesn’t allow substance to pass through. Permeability can be changed by altering proteins, lipids of membrane Moves easily: oxygen, carbon dioxide, lipids Moves with difficulty: ions, most polar molecules, very large molecules Permeability influenced by: 1) size of molecule 2) lipid solubility - smaller molecules and lipid soluble crosses directly through phosolipid bilayer Membrane proteins are usually mediator cells used to transport molecules across membranes Passive transport: doesn’t require use of energy Active transport: required input of energy from outside source, high-energy phosphate bond of ATP Diffusion uses only the energy of molecular movement Passive transports required kinetic energy Diffusion: movement of molecules from an area of higher concentration to an area of lower concentration of molecules Seven properties of Diffusion: 1) passive process: a. doesn’t require the input of energy from outside source 2) molecules move from high concentration area to lower concentration area a. concentration gradient: difference in concentration of a substance between two places i. also known as chemical gradient b. down the gradient: from higher concentration to lower concentration c. rate of diffusion: depends on magnitude of concentration gradient i. larger concentration gradients differences- FASTER it takes place d. net movement of molecules occurs until concentration is equal everywhere: i. after molecules of substances have distributed evenly, system reaches equilibrium and diffusion stops ii. dynamic equilibrium state: concentration has equalized through system but molecules continue to move e. diffusion is rapid over short distances but much slower over longer distances f. diffusion is directly related to temperature
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i. diffusion results from molecular movement so rate of diffusion increases as temperature increases ii. in humans: no significant impact because maintain relatively constant body temperature g. diffusion rate is inversely related to molecular size
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Weeks 1 and 2 Notes - Diffussion Ion Pumps Resting...

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