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Resting membrane potential by DR. IRUM
- 2. By Dr Irum Junaid
- 6. Ion Inside Outside Cross PM K+ 140 4 yes NA+ 14 142 no Cl- 5 125 yes H2O 55,000 55,000 yes Anion- 108 0 no
- 12. OUTSIDE INSIDE K + = Potassium ; Na + = Sodium ; Cl - = Chloride ; Pr - = proteins + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - Closed channel open channel open channel no channel Resting Membrane Potential - 65 mV Na + Na + K + K + Force of Diffusion Electrostatic Force Cl - Force of Diffusion Cl - Electrostatic Force Pr - 3Na/2K pump
- 20. Action Potentials Can travel up to 100 meters/second Usually 10-20 m/s 0.1sec delay between muscle and sensory neuron action potential
Notes de l'éditeur
- Charged particles are called ions. Negatively charged ones are ‘anions’, while positive ones are ‘cations’. Proteins are negatively charged particles and they remain inside the cell
- Ion channel : A specialized protein molecule that permits specific ions to enter or leave the cell. Voltage-dependent ion channel : An ion channel that opens or closes according to the value of the membrane potential. Depolarization: Reduction (toward zero) of the membrane potential of a cell from its normal resting potential. Normal depolarizing events are termed EPSPs – excitatory post-synaptic potentials – and result from opening of Na+ channels. Hyperpolarization: An increase in the membrane potential of a cell, relative to the normal resting potential. Hyperpolarizing events are termed IPSPs – inhibitory post-synaptic potentials – and result from opening of Cl- channels (Cl- higher outside than in, so flow in and make cell more negative). Also can result from opening K+ channels. Action potential : The brief electrical impulse that provides the basis for conduction of information along an axon. Threshold of excitation : The value of the membrane potential that must be reached to produce an action potential. Cable properties : The passive conduction of electrical current, in a decremental fashion, down the length of an axon. Saltatory conduction ; Conduction of action potentials by myelinated axons. The action potential appears to jump from one node of Ranvier to the next. All-or-none law : The principle that once an action potential is triggered in an axon, it is propagated without decrement to the end of the fiber. Rate law : The principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires.