PS111A Lecture 1 color.ppt

PS111A Lecture 1 color.ppt - PHYSIOLOGICAL SCIENCE 111A...

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PHYSIOLOGICAL SCIENCE 111A Professor Peter Narins Winter 2010 Lecture 1- Introduction
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Peter Narins Office: LS 4835 E-mail: [email protected] Office Hours: M,W 1-2 pm LS 4835
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This course will focus on excitable cells [e.g. neurons and muscle cells (myocytes)] which have a membrane potential (V m ) that can be modified and and in that way, signal information
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O - The membrane is a highly selective filter that: – maintains unequal concentrations of ions across it – allows nutrients to enter and waste to leave the cell Also responsible for Vm, membrane potential. It has two main components: 1) Phospholipid bilayer (3 classes) a)Phosphoglycerides – most abundant of phospholipids; have glycerine backbone; amphipatic molecules - have a polar, hydrophilic head; and non-polar, hydrophobic tails e.g. phosphatidyl choline O O O +
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b) Sphingolipids have a sphingosine backbone; amphipatic molecule e.g. sphingomyelin c) Sterols – non-polar e.g. cholesterol Singer-Nicolson Fluid-Mosaic model of the membrane Based on the spontaneous organization of amphipatic molecules Lipid Bilayer:
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Singer-Nicolson Fluid Mosaic Membrane Model
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Membrane Protein Function 2) Proteins – form an integral part of the membrane The membrane itself is impermeable to ions - proteins allow passage of ions through the membrane Functions: a) enzymes - catalyze reactions b) receptor molecules for hormones, etc. c) passive channels/pores - allow entry/exit of substances through the membrane d) pumps - active transport across the membrane e) carriers - passive transport: the protein binds to
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Membrane Function Membranes divide cells into physically separate compartments, which allows: 1) Control of solute concentrations 2) Storage of energy to do work a) chemical energy - by establishing concentration or electrochemical gradients b) electrical energy - by establishing charge separation » This sets up the membrane potential
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Passive Diffusion Passive Diffusion permeation - the passive diffusion of solutes across a barrier Fick’s Law of Diffusion: dS/dt = P x (C 1 -C 2 ) dS/dt : the amount of a substance crossing a unit area/unit time (Mol/cm 2 s) P x : permeability constant of the membrane to x (cm/s) C 1 -C 2 : change in concentration across the membrane (Mol/cm 3 )
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This note was uploaded on 02/03/2010 for the course NEUROSCI 101A taught by Professor Scheibell during the Winter '10 term at UCLA.

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PS111A Lecture 1 color.ppt - PHYSIOLOGICAL SCIENCE 111A...

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