Can you identify the sequence of events at a synapse?To review what happens at a synapse in response to an action potential, watch this BioFlix animation
The Correct Answer and Explanation is :
The sequence of events at a synapse in response to an action potential involves several key steps:
- Action Potential Arrival: An action potential travels down the axon of the presynaptic neuron and reaches the axon terminal.
- Depolarization of the Presynaptic Terminal: The arrival of the action potential causes depolarization of the presynaptic terminal membrane.
- Opening of Voltage-Gated Calcium Channels: The depolarization opens voltage-gated calcium (Ca²⁺) channels in the presynaptic membrane.
- Calcium Influx: Calcium ions flow into the presynaptic neuron due to the concentration gradient.
- Neurotransmitter Release: The increase in intracellular calcium concentration triggers the fusion of synaptic vesicles containing neurotransmitters with the presynaptic membrane, leading to the release of neurotransmitters into the synaptic cleft.
- Diffusion Across the Synaptic Cleft: The released neurotransmitters diffuse across the synaptic cleft to the postsynaptic neuron.
- Binding to Postsynaptic Receptors: Neurotransmitters bind to specific receptors on the postsynaptic membrane.
- Postsynaptic Response: The binding of neurotransmitters to receptors causes ion channels in the postsynaptic membrane to open or close, leading to changes in the postsynaptic neuron’s membrane potential.
- Termination of Signal: The neurotransmitter’s action is terminated by its removal from the synaptic cleft, which can occur through reuptake into the presynaptic neuron, enzymatic degradation, or diffusion away from the synapse.
This sequence ensures the transmission of signals from one neuron to another, facilitating communication within the nervous system.