Mam Fizz Notes Through 1-18

Mam Fizz Notes Through 1-18 - Mam Fizz 1 Teaching Assistant...

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Unformatted text preview: Mam Fizz 1 Teaching Assistant Chris Childers Table of Contents Lecture 2 of 11 Lecture 1 / January 4 th , 2010 Intro & Overview Diffusion (pp 133-141) Osmosis (pp 158-163) Transporters, Channels, Pumps (pp 141-151, 154-157) Membrane Potentials (pp 164-171, 255-258) 2 Midterm Exams (20% each, short answer): Friday, January 29 th , 2-2:50p Friday, February 26 th , 2-2:50p Final (60%, multiple choice): Monday, March 15 th , 3-6p -- Figure 5-1 Steady State vs. Equilibrium - In both a steady state and equilibrium, things are moving - In equilibrium, nothing changes with time (reactions and products are still being formed and broken, but there is no net change in the concentration) o Zero free energy o Animals and their cells (living organisms) are not in equilibrium - A steady state has a constant input and constant output, maintaining a fairly consistent concentration o Free energy is not zero o Also called mass balance o Animals (and living cells) do have steady state parameters o Examples: pH and temperature are both within very narrow ranges; glucose has a larger range Membrane Physiology - Lipid Bilayer o Hydrophobic o Barrier against anything charged/polar (hydrophilic molecules - water, ions, glucose, amino acids etc.) o Does NOT block lipophilic (hydrophobic) molecules (gases O2, CO2, CO, N2O; alcohol, drugs opiates, aspirin; steroid hormones, thyroid hormones, fat-soluble vitamins) - So how do hydrophilic molecules cross the membrane? Need a hole o Pores are not very common (dont allow steady states) o Channels are much more common small pathways filled with water, selective for different molecules (typically ions) ion channels When the channel is selective for water by itself aquaporins Leak channels always open Gated channels only open upon stimulus (electrical voltage gated, mechanical sensory [touch, pressure, vibration, acceleration, hearing etc.], temperature [cold and hot], chemical [NTs]) o Transporters proteins with binding sites for the transported molecule; upon binding conformational change translocate molecule from one side of the membrane to the other) GLUT transporters o Pumps active transport systems using ATP to transport ions (most famous Na+/K+ ATPase; others Ca2+-ATPase) 3 of 11 Lecture 2 / January 6 th , 2010 Mechanisms of Ion Pumps Diffusion: Ohms Law, Ficks Law Symports & Antiports, Secondary Active Transport Osmosis & Tonicity Electrochemical Gradients Nernst Equation Goldman Hodgkin Katz Equation Ion Pumps: - Probably the most famous is the Na+/K+ ATPase, located within the plasma membrane; also, Ca2+ ATP-ases located in the endoplasmic reticulum - They break a phosphate bond in ATP and use the free energy to pump ions across the membrane - 70% of the energy in the brain is used to create ATP which is used by the Na+/K+ pump - Over 99% of the energy in the kidney - Enzymes are self regulated o...
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Mam Fizz Notes Through 1-18 - Mam Fizz 1 Teaching Assistant...

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