(a) g K, V m = E K (b) g Na >> g K, sodium influx (c) g K >> g Na, pottassium efflux (d) g K, V m =...
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Transcript of (a) g K, V m = E K (b) g Na >> g K, sodium influx (c) g K >> g Na, pottassium efflux (d) g K, V m =...
(a) gK, Vm = EK
(b) gNa >> gK, sodium influx
(c) gK >> gNa, pottassium efflux
(d) gK, Vm = EK
A Mechanism for the Action Potential
Action Potential Conduction (part I)
• Entry of positive charge during the action potential causes the membrane just ahead to depolarize to threshold. Because the axonal membrane is excitable the action potential travels without decrement.
• Typical conduction velocity:10 m/sec
• Conduction velocity increases with axonal diameter
• Stellate cell-constant firing rate
• Pyramidal cell-Adaptation, decreased firing rate over time OR,
•Bursting, rapid cluster of action potentials followed by a pause.
Neurons Exhibit Different Patterns of Action Potential Generation
Action potentials invading the axon terminals cause the release of chemical neurotransmitters
• transmit a chemical signal (known as neurotransmitters)
• receive signals through receptors that bind neurotransmitters
• Can study receptor subtypes using different drugs
• One neurotransmitter can bind to multiple receptor types
• No two transmitters bind to the same receptor
There can be multiple receptor subtypes
Cholinergic synaptic transmissionHeterogeneous localization of receptors
(e.g. - heart versus skeletal muscle)
Agonists versus antagonists
Glutamatergic synaptic transmission
Dendrites integrate information from multiple inputs
The Action potential
Integrated synaptic inputs determines whether a neuronreaches threshold to fire an action potential
Experience can modify the contribution of inputs
Drugs can alter synaptic communication between neurons
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