Action potential: Anatomy and Physiology

Question

Short answer response:

What could a surface receptor do to modulate a graded potential in dendrites?

Answer 1

Great question! Think about what a neuron does. It wants to make an action potential right? And it is going to be told when to do that by surface receptors that bind to neurotransmitters. What is an action potential though, and what causes it? Remember that the neuron uses ions (salts like Na, Ca, K) to make an "electrical" gradient. Do you think that neurotransmitter receptors are linked to channels that allow these salts to move into or out of the cell? Most neurotransmitters are linked to receptors that open or close channels. When you get a large shift in the electrochemical gradient in the cell, you have an action potential, and the neuron send a signal down its axon.

So putting that all together you can see how a surface receptor might modulate the graded potential. If you let more ions into the cell and get closer to the depolarization threshold for that neuron, or if you open a different channel that inhibits the neuron from firing (makes it more polarized), you have changed the membrane potential.