Hello, lil1butterflypb5u0t!! I have recently taken Anatomy and Physiology this past year and I was able to keep my book. According to my book, I think it would be answer C - release calcium into an axon. For this to happen, several things have to happen before this takes place. Think about whenever you send a text message to someone; you are the sender (presynaptic neuron) and the person receiving it would be the postsynaptic neuron. Whenever a presynapse neuron sends an impulse to a postsynapse neuron, it is called synapse transmission. What synapse transmission means is that the presynapse neuron stimulates the postsynapse neuron. When this happens, an impulse travels along the axon of the presynaptic neuron to the axon terminal. You can always think of an axon sending an impulse away from the cell body. Axon=away. Most axons have several rounded synaptic knobs at their terminals, but dendrites do not. Dendrites receive the input from the other neurons. When an impulse reaches the synaptic knob, calcium channels open and calcium diffuse inward from the extracellular fluid. When this happens, it starts a chain of events that fuses the synaptic vesicles with the cell membrane, and they release neurotransmitters. When the neurotransmitters bind to receptors on a postsynaptic cell, the action is either excitatory or inhibitory. The binding causes the receptor to change shape. Next, the ion channels open (Na - Sodium, and K - Potassium). After that, graded potentials are created. And finally, neurotransmitters are recycled three different ways: reputable, enzyme degradation, and diffusion. I really hope this is right!! This came out of my textbook, so it should be. Have a great evening and I hope I helped you!! If you have any more questions then do not hesitate to ask me.
