Psyc4130 1nd Edition Lecture 4 Outline of Last Lecture I Basics of Neurophysiology A Glial cells neuron cells nervous system CNS matter neuroglia II Four Types of Glial Cells A Astrocyte B Microglia V VI C Oligodendrocyte D Schwann Cell Neurons and Terms A Neuron parts Different Neurons A Bipolar cells B Multipolar Cells About Cells Eukaryotic Cells VII General Physiology Neuron Terms III IV Outline of Current Lecture II Blood Brain Barrier III Important terms concepts A Action Potential B Phospholipid IV Three Potentials A Resting potential B Graded potential C Action potential Current Lecture Blood Brain Barrier o Keeps most bad stuff out including large molecules they get stuck in capillaries unless they specifically get carried across Plant toxins and bacteria for example These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o o o o Imuno compromise hard to get rid of if it is bad Selective about which ions it ll transport across high sodium concentration Limits amount of exchange of sodium chloride and potassium ions Formed by tight junctions of the capillaries feeding CNS Less leaky Allow for ions to be exchanged easily o Brain gets nutrition from specific transporters one at a time very specific Pt 2 Important Terms Concepts o Selective Permeability of cell membrane o Membrane Resting Potential o Depolarization and Hyperpolarization EPSPs and IPSPs o Threshold of Excitation o Action Potential Electrochemical events the batteries based upon ion flow across a membrane Neural communication occurs via action potentials cells firing Relative balances of positively and negative ions inside and outside of the neuron provide the stored energy that is released during the action potential Think battery o Cations and Anions o Extracellular Fluid o Intracellular Fluid aka Cytosol o Sodium Potassium Transporters Pumps o Ion Channels Voltage Dependent Ligand Gated o All or None Law o Saltatory Conduction Phospholipid o When phospholipids contact water the hydrophobic fatty acid tails automatically align away from water molecules forming a double layer barrier with water inside and outside Hydrophobic tail hates water Hydrophilic head likes water 3 Potentials Resting potential o Membrane potential storing the energy to be released during action potential o Big player number 1 the sodium ion positive charge 1 Higher concentration of sodium outside of axon Graph below NA concentrations during rest o Big player number 2 Potassium Ion High concentration of potassium K inside of axon low outside o Sodium Potassium Pump Helps maintain relative concentrations The neuron spends roughly of its energy to run the sodium potassium pump It pays a fortune to remain quiet o Chloride More concentrated inside o Big player 3 Organic ions More concentrated inside negatively charged e g proteins Important for test o Inside of cell is more inside of axon relative to outside o Averages 70 mV o More organic ions Membrane potential conclusions o Concentration Gradient Ionic Force Flow is from high concentration to low o Electrostatic Force Opposites attract o Inside cytoplasmic face of cell is negative with respect to ECF 70mV Much force wants to push sodium into the neuron at resting potential Graded potentials o Threshold of excitation Action potentials are all or nothing events It is absolutely essential that the polarity of the inside of the cell relative to the outside drop from 70 to 55 mV threshold Sodium ions rush in less concentrated inside more outside positively charged ions and inside is more negative opposites attract drives sodium to rush in to local area of axon Once this happens at the axon hillock the action potential occurs automatically Must depolarize it Ligand molecule that binds and opens up receptor causes protein to shif Depolarization excitatory neuron Action potential o In order to get an action potential the inside of the cell must be sufficiently depolarized to open voltage dependent ion sodium channels o Brief local transient reversal of polarity o Inside of the axon during action potential for a fraction of a sec is more positively charged than the outside Na channels open allow sodium in going up on hill going down on hill K channels eflux plumits overshoots 70 before it closes
View Full Document
Unlocking...