membrane potential becomes more negative,
membrane potential becomes less negative,
Graded (or proportional)
intensity of stimulation reaching thershold potential
reaching threshold potential results in a nerve impulse
Absolute Refractory Period
Time when threshold stimulus does not start another action potential
Relative Refractory Period
Time when stronger threshold stimulus can start another action potential
where released neurotransmitters cross synaptic cleft and react with receptors in postynaptic neuron membrane
Open & Close Ion Channels
Excitatory Postsynaptic Potential
depolarizes membrane of postsynaptic neuron - action potential becomes more likely
Inhibitory Postsynaptic Potential
hyperpolarizes membrane of postsynaptic neuron - action potential becomes less likely
When EPSP and IPSP are added together
More EPSPs lead to greater probability of AP
act as neurotransmitters and are synthesized by the neurosn in brain & spinal chord
EX of neuropeptides
Enkephalins, Beta endorphin, Substance P
Interneurons working together to perform common function (excite or inhibit)
Various sensory receptors - can allow for summation of impulses
Branching axon - stimulation of many neurons ultimately
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