Exam _2 study guide - Exam #2 Study guide Chapter 6...

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Exam #2 Study guide Chapter 6 – Interactions Between Cells and the Extracellular Environment Body fluids are divided into two compartments: Intracellular compartment (inside cell): 67% of the total body H 2 O Extracellular compartment (outside of cell): 33% of the total body H 2 O Categories of transport across the plasma membrane Carrier mediated transport : facilitated diffusion and active transport Non-carrier mediated transport : diffusion and osmosis (or categorized by energy requirements) Passive transport : net movement down a concentration gradient (does not require metabolic energy; only thermal energy) Active transport : net movement against the concentration gradient (requires metabolic energy) Diffusion Brownian motion – random molecular movement (stops only at absolute zero) Diffusion through plasma membrane o Cell membrane is permeable to… Non-polar molecules (O 2 ) Lipid soluble molecules (steroids) Small polar covalent bonds (CO 2 ) H2O (small size, lack charge) o Cell membrane is impermeable to…. Large polar molecules (glucose) Charged inorganic ions (Na + ) ** Basically…. Non-polar & very small polar molecules get through; larger polar molecules and ions do not get through Rate of diffusion Speed at which diffusion occurs is dependent on The magnitude of the concentration gradient (Higher magnitude higher rate) The permeability of the membrane (More permeability higher rate) Temperature (Higher temperature higher rate) Surface area of the membrane (greater surface area higher rate) Osmosis : movement of water from higher concentration to lower concentration through a semi- permeable membrane (for osmosis to occur, the semi-permeable membrane must be more permeable to H 2 Osmotically active solutes : cannot pass freely through the semi-permeable membrane (which “drives” the water to move, since the solute cannot) Osmotically inactive solutes : can pass freely through the semi-permeable membrane (which “drives” the solute to move through the membrane to reach equilibrium) Page 1 of 18
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Exam #2 Study guide Osmotic pressure : the force that would have to be exerted to prevent osmosis Tonicity : the effect of a solution on the osmotic movement of H 2 O Isotonic : cell has equal tension to plasma – RBCs will not gain or lose water (approximately equal amount of water molecules inside the cell and outside the cell) Hypotonic : Osmotically active solutes in a lower osmolality & osmotic pressure than plasma – RBCs will hemolyse (RBC has less water than the pure water environment – water will “flood” into the RBC, exploding it) Hypertonic : Osmotically active solutes in a higher osmolality & osmotic pressure than plasma – RBCs will crenate (RBC has more water than the “sea water” environment – water will exit the RBC, causing it to “shrivel”)
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Exam _2 study guide - Exam #2 Study guide Chapter 6...

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