3-Membrane Dynamics Figs BW Corrected

Alternately in the fast state glycogen that is stored

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Unformatted text preview: e of body. alternately In the Fast state, glycogen that is stored in the liver is broken down in liver cells into glucose, by a process of ***glycogenolysis***. that glucose exit the cell through transporters (GLUT).***glut 2 also act as glucose sensor in pancreatic beta cell, which release insulin when plasma glucose concentration is too high GLUT3 is the main glucose transporter in neurons. neurons have high metabolic rate, and do not store glucose as glycogen so neurons are very dependent on continuous transport of glucose into the cell via GLUT3 transporters GLUT4 is the insulin-responsive GLUCOSE specific transporter. it is responsible for the action of insulin in stimulating glucose uptake in muscle and fat cells (defects possible) GLUT5 is a fractose specific transporter. it helps carry out fractose absorption in the intestine for nutrient and sperm cell (need energy source) Facilitated Diffusion GLUT1 ++ + - + + High capacity; small Many cells Glucose GLUT2 + intestine, liver, “glucose sensor” in pancreatic β-cells GLUT3 ++ + - Main glucose transporter in neurons GLUT4 ++ - - Insulin-responsive, in skeletal & cardiac muscle, adipocytes GLUT5 ICF ECF - - ++ = high affinity + = low affinity + Many cells, especially in small intestine & sperm Primary Active Transport Antiports Na+/K+ ATPase H+/K+ ATPase ECF all primary active transport are pump or ATPase. all 4 are important in moving ions across membranes.2 of the transporters are antiports (carry ions in 2 opposite direction). 2 active transporters are uniports (carry one one ion): calcium and proton. sodium potassium ATPase is most ubiquitous. -3 sodium ion pump out of cell for every 2 potassium ion pump in. t...
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This document was uploaded on 03/09/2014 for the course EXSC 301 at USC.

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