Transcript The Action potential

A Mechanism for the Action Potential
(a) gK, Vm = EK
(b) gNa >> gK, sodium influx
(c) gK >> gNa, pottassium efflux
(d) gK, Vm = EK
Action Potential Conduction (part I)
• Typical conduction velocity:
10 m/sec
• Conduction velocity increases
with axonal diameter
• 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.
Neurons Exhibit Different Patterns of
Action Potential Generation
• Stellate cell-constant firing rate
• Pyramidal cell-Adaptation, decreased firing rate
over time OR,
•Bursting, rapid cluster of action potentials
followed by a pause.
Action potentials invading the axon terminals
cause the release of chemical neurotransmitters
Neurons can:
• transmit a chemical signal (known as neurotransmitters)
• receive signals through receptors that bind neurotransmitters
There can be multiple receptor subtypes
• Can study receptor subtypes using different drugs
• One neurotransmitter can bind to multiple receptor types
• No two transmitters bind to the same receptor
Cholinergic synaptic transmission
Heterogeneous 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 neuron
reaches threshold to fire an action potential
Experience can modify the contribution of inputs
Drugs can alter synaptic
communication between neurons
COCAINE
• euphoria
• reduced hunger
• feeling of strength
This is your brain.
This is your brain ...