BIOL 318: CH. 12 - SUMMATION

How many synaptic terminals can a postsynaptic neuron receive inputs from?

A postsynaptic neuron can receive inputs from hundreds or thousands of synaptic terminals.

What part of the neuron receives inputs from synaptic terminals?

The cell body of the postsynaptic neuron receives these inputs.

Can a single postsynaptic neuron interact with multiple synaptic terminals?

Yes, a single postsynaptic neuron can interact with inputs from numerous synaptic terminals.

Why is it significant that a postsynaptic neuron can receive inputs from so many terminals?

It allows the neuron to integrate a wide range of signals, influencing its activity and response.

What typically happens when a single EPSP occurs in a postsynaptic neuron?

When a single EPSP occurs in a postsynaptic neuron, a single EPSP is usually too small to trigger an action potential.

What type of channel activity generates an EPSP?

A ligand-gated ion channel permeable to Na+ generates an EPSP.

How does the generation of an EPSP affect the postsynaptic neuron?

It causes depolarization, moving the membrane potential closer to the threshold for an action potential.

What is the process called when individual postsynaptic potentials combine to produce a larger postsynaptic potential?

The process is called summation.

What effect occurs if two EPSPs are produced in rapid succession?

If two EPSPs are produced in rapid succession, an effect called temporal summation occurs.

What is spatial summation?

Spatial summation occurs when EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron add together.

How can the combination of EPSPs through spatial and temporal summation affect the postsynaptic neuron?

The combination of EPSPs through spatial and temporal summation can trigger an action potential.

What is the role of summation in counteracting the effect of an EPSP?

Through summation, an IPSP can counter the effect of an EPSP.

Which type of ion channel is involved in generating an IPSP, and what is its effect on the membrane potential?

A ligand-gated ion channel permeable to Cl- or K+ generates an IPSP, which leads to hyperpolarization, moving the membrane potential away from the threshold.

What determines whether an axon hillock will reach threshold and generate an action potential?

The summed effect of EPSPs and IPSPs determines whether the axon hillock will reach threshold and generate an action potential.