Bipn%20100%20Section%2012 - Open channels(aka leak...

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Bipn 100 Section 1/12/10 Homeostasis – Steady State – Equilibrium – Diffusion – Do ions move by diffusion? What two factors influence ion movement? 1. 2. Therefore ions move through a ______________ gradient not a concentration gradient. Fick’s Law of Diffusion: Rate of diffusion α (Surface Area x concentration gradient x permeability) Membrane thickness Since cells are selectively permeable. Permeability depends on: 1. 2. 3. How does water travel through the membrane? 1. 2. Simplified Fick’s Law of Diffusion: Temperature is directly related to diffusion rate in an open system. Why doesn’t Fick’s Law take temperature into consideration? Would the permeability of a cell increase or decrease with more cholesterol?
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Unformatted text preview: Open channels (aka leak channels/pores) – channels that are usually open Gated channels – channels that spend most their time closed Stimulus to open: 1. 2. 3. Drawing of enterocyte in intestine: During homeostasis where will you usually find Na+, K+ and Cl-? (intracellular or extracellular) If there were no glucose in the lumen, what would happen to the Na+/K+ ATPase? What would happen if you poison an enterocyte with ouabain? Equilibrium potential – Nernst equation: *Only applicable when a cell is permeable to one ion* What is the equilibrium potential for a cell with 5mM of Cl- on the inside and 100 mM of Cl- on the outside? What does this number represent?...
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Bipn%20100%20Section%2012 - Open channels(aka leak...

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