Spatial and Temporal Summation

Trigger zone

The graded potentials combine at the _____ _____ of the postsynaptic neuron

Threshold

A single postsynaptic potential is usually not strong enough to reach _____

Action potential

If the combination of graded potentials reaches or exceeds threshold at the trigger zone, an _____ _____ is produced

Graded potentials

Many _____ _____ are produced in the postsynaptic membrane at a given time

Combined summation

Occurs when spatial and temporal summation occur at the same time

Temporal summation

Occurs when two or more graded potentials are produced at a given location on the neuron's cell body or dendrites in such rapid succession that they can summate at the trigger zone Increase in frequency

Spatial summation

Occurs when two or more graded potentials from different locations on the neuron's cell body or dendrites reach the trigger zone simultaneously Increase in number across the cell

Na+

The trigger zone has a concentration of _____ channels that is 7x greater than elsewhere on the cell body