Exam 1 Guide

Exam 1 Guide - CSF has same amount of sodium. It is more...

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CSF has same amount of sodium. It is more acidic. It has less potassium, glucose, calcium and bicarbonate. -Because it has same Na it has the same rising phase of the action potential depolarization. Since there is less potassium, you hyperpolarize the neuron a little. -More acidic “bad things happen”- effects are mediated by a state of ionization. -Less calcium. Normally outside is less negative because the calcium binds to some of the negative charge on the outside and neutralizes it. If you have too little calcium, then there is less calcium bound to the outside, causing the outside to be more negative, which depolarizes. -If hypercalcemic, the external environment is more neutral, which hyperpolarizes the cell. -Potential across the membrane is way more negative when concentrated near the -membrane than in more interior or exterior portions of the cell Lecture 2 Transport Across Membranes Diffusion: increases with concentration, increases with temperature, decreases with distance, increases with surface area, decreases with molecular size, and increases with solubility. Facilitated Diffusion Active Transport Osmosis Exo/Endocytosis Primary Active Transport The energy to push molecules against their concentration gradient from the high energy phosphate bond of ATP. ADP is hydrolyzed to ATP. (secondary uses potential energy) Na+,K+, ATPase- single most important protein because it maintains concentration gradient. Na/K pump pumps 3Na+ out while pumping 2K+ in Secondary Active Transport Uses potential energy gradient. Solute moving down its concentration. Example is Sodium Glucose Symporter: local in the apical membrane. GLUT transporter is in the baso-lateral membrane. Transepithelial Glucose Transport Glucose moving across the epithelia from the apical (facing lumen) to the basal lateral (away). 1. SGLT brings Na+ and glucose into the cell. SGLT relies on low Na+ ICF. High Na+ levels in ICF would disrupt this transporter. a. Na+ binds to SGLT carrier b. Causes conformational change allowing glucose to fit c. Glucose binding changes carrier conformation d. The Na+ is released into cytosol with glucose. 2. GLUT transporter then moves glucose via facilitated diffusion into basal lateral membrane.
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3. Na+/K+ ATPase pumps Na+ to ECF of basal lateral side. The K+ does not accumulate because of the high concentration of leaky potassium concentrations that allow for its diffusion out of the lumen. 4. Glucose then diffuse to E.C. then diffuses to blood NaCl and H20 Transport in Lung 1. CFTR opens when phosphorylated. The phosphorylation is caused by protein kinase-A, which is cyclic AMP dependent. Cl- leaves the cell 2. Na+ moves out to the mucous via the ENac epithelium Na+ channel, which is always open, because of the negative electrical gradient that is established in the mucous. 3.
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This note was uploaded on 05/03/2010 for the course BISC 307L taught by Professor Herrera during the Spring '08 term at USC.

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Exam 1 Guide - CSF has same amount of sodium. It is more...

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