Figure Q3-6 Is from an Experiment That Helped Show That

question 21

Essay

Figure Q3-6 is from an experiment that helped show that neurotransmitter release is triggered by presynaptic Ca²⁺. In panel A, the presynaptic membrane potential was clamped at -25mV. Figure Q3-6
A. How did they know Ca²⁺ entered the presynaptic neuron?
B. What happened in the postsynaptic neuron?
C. In panel B, the presynaptic membrane potential was clamped at -50mV. Why was there no net current during the presynaptic depolarization?
D. Why was there a current after the presynaptic potential was clamped back to -70mV?
E. What happened to the delay in postsynaptic current with the +50mV presynaptic depolarization?

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Definitions:

Synaptic Cleft

The narrow space between the terminal button of a neuron and the dendrite or cell body of another neuron where neurotransmitters are released.

Inhibitory Postsynaptic

Referring to a postsynaptic potential that makes a neuron less likely to generate an action potential, essentially serving to inhibit neuronal firing.

Neuron

A nerve cell that is the basic building block of the nervous system, responsible for receiving and transmitting information through electrical and chemical signals.

Action Potential

A rapid rise and subsequent fall in voltage or electrical charge across a cell's membrane, allowing neurons to transmit signals over distances.