Lecture 03 Resting Membrane Potential

Lecture 03 Resting Membrane Potential - The Resting...

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The Resting Membrane Potential Chapter 3
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Electrical signals • Nerve cells (neurons) transmit information with electrical signals • Nerve cells are not intrinsically good electrical conductors – A copper telephone wire transmit information fast because it is a good conductor of electrons, but – Neurons generate their electrical signals with _______ crossing the cell membrane
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What’s an ion? • Ion = atom or molecule with an electrical charge • Regular table salt is NaCl. When salt dissolves in water you get _______ ions, Na + , and ______ ions, Cl - • Neurons are bathed in a salty extracellular fluid containing Na + , Cl - , K + (potassium), and Ca 2+ (calcium) among others
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Ions can not cross the membrane other than through ____ __________ • Neurons have a membrane made up of a phospholipid bilayer • The phospholipid bilayer isolates the inside of the neuron from the extracellular fluid
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Ions pass through ion channels to get through the membrane • Ion channels are _______ in the membrane • They are typically made up of 4-6 subunits, forming a pore in the center • The type of subunits put together decides which ion can pass through • There are K + selective channels, Na + selective channels, Cl - selective channels etc.
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Will the ion go through the ion channel? How ions move are decided by two forces: 1. ____________ 2. ____________
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• Diffusion acts to distribute ions ______ in a solution – Ions move from regions of high concentration to regions of low concentration
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Because ions are charged, _________ ___________ can move them There is a membrane dividing the solution in two compartments When channels are inserted in the membrane, ions move according to their electrical charge
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The resting membrane potential If a microelectrode is inserted into a neuron at rest, the voltmeter shows a negative potential This potential is caused by uneven distribution of electrical charge across the membrane In this case it is -65 mV, that is, the inside is 65 mV more __________ than the outside
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Equilibrium potential Inside “cell” Outside “cell” There is 20 times more K+ and anions (A-, any negative ion) inside the cell compared to outside. But in this case there is no movement of ions
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Lecture 03 Resting Membrane Potential - The Resting...

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