Graded membrane potentials:Rely heavily on voltage gated ion channelsAre excitatory when they make membrane potential more negativeAre excitatory when they hyperpolarise the cellHelp determine whether a neuron will reach threshold

Graded membrane potentials:

1. Do not rely heavily on voltage-gated ion channels: Graded potentials are changes in membrane potential that vary in size, as opposed to being all-or-nothing. They occur in the dendrites and cell body of a neuron, areas that are typically not abundant with voltage-gated ion channels. Instead, they rely more on ligand-gated or mechanically-gated ion channels.

2. Are not excitatory when they make the membrane potential more negative: Making the membrane potential more negative is known as hyperpolarization. This moves the membrane potential further from the threshold, not closer, and thus inhibits the neuron from firing an action potential. Therefore, it is inhibitory, not excitatory.

3. Are not excitatory when they hyperpolarize the cell: As mentioned above, hyperpolarization is inhibitory, not excitatory. It makes the inside of the neuron more negative, moving the membrane potential further from the threshold and making it less likely to fire an action potential.

4. Help determine whether a neuron will reach threshold: This is true. Graded potentials can either depolarize (make more positive) or hyperpolarize (make more negative) the neuron. If the sum of all graded potentials depolarizes the neuron to the threshold, an action potential will be fired. Therefore, graded potentials play a crucial role in determining whether a neuron will reach the threshold and fire an action potential.