Download Understanding the Resting Membrane Potential and Ion Channels in Neurons - Prof. Steven E. and more Study notes Psychology of Human Development in PDF only on Docsity! 1 Listen to the audio lecture while viewing these slides 1 Psychology 372 Physiological Psychology Steven E. Meier, Ph.D. Membrane Neurophysiology Overview of the Neuronal Membrane, Associated Ions, and Ion Channels 2 Psyc 372 – Physiological Psychology Structure of a Neuron at Rest + + + + + + + + + + + + + Na+ Cl- _ _ _ _ _ _ _ _ _ _ _ _ _ _ K+ Anions - 3 Psyc 372 – Physiological Psychology Measuring the Difference Between the Inside and Outside of a Neuron • A axon from a giant squid is placed in seawater in a recording chamber. • Glass microelectrode is inserted into axon. • Voltage measures inside with respect to outside -70 mV Chamber Axon Voltmeter Microelectrode 4 Psyc 372 – Physiological Psychology Resting Membrane Potential • Is the difference in voltage between the inside and outside of the axon membrane. 5 Psyc 372 – Physiological Psychology Concept • Influx Material (Ions) moving to the inside of a membrane. • Efflux Material (Ions) moving from the inside to the outside of a membrane. • Equilibrium • Where material (ions, concentrations, etc.) are equal on both sides of a membrane. 6 Psyc 372 – Physiological Psychology Why do Ion’s Move? • Concentration Differences • Compounds move from high concentrations to lower concentrations. • Electrostatic Pressure • Like charges repel each other • Opposite charges attract each other. 2 7 Psyc 372 – Physiological Psychology Why is There a Resting State? • The neuron membrane is selectively permeable to certain ions. • Sodium Na+ • Potassium K + • Chloride Cl – • Calcium Ca++ 8 Psyc 372 – Physiological Psychology Resting State • At rest, K+ ions can leave the axon while few Na ions can enter the axon • Causes the exterior of the nerve cell membrane to be more positive than the inside of the axon 9 Psyc 372 – Physiological Psychology Result • Have high concentrations of Na and Cl on the outside of the axon • High concentrations of K and Anions on the inside of the axon. 10 Psyc 372 – Physiological Psychology Ion Concentrations at Rest High Na+ High Cl- Low K High K+ Anions - Low Na 11 Psyc 372 – Physiological Psychology Relative Ion Concentrations Across the Axon Membrane 12 Psyc 372 – Physiological Psychology Channels • Axons have two types of channels or pores for different ions. • Passive Channels • Are open all of the time and allow ions to pass through the membrane. • Voltage Gated Channels • Are activated by changes in voltage • E.g., voltage-gated Na channels
