Question

Explain the processes that lead to the exocytosis of neurotransmitter from a presynaptic cell. which components are recycled? which ion is important in triggering exocytosis?

Answer 1

Exocytosis is the process by which neurotransmitters are released from a presynaptic cell. Calcium ions play a crucial role in triggering exocytosis, causing the fusion of neurotransmitter-containing vesicles with the presynaptic membrane.

Step-by-step explanation:

Exocytosis is the process by which neurotransmitters are released from a presynaptic cell. When an action potential arrives at the terminal button, voltage-gated calcium channels open, causing an influx of calcium ions into the cell. The increased concentration of calcium inside the cell triggers the fusion of neurotransmitter-containing vesicles with the presynaptic membrane, leading to the release of neurotransmitters into the synaptic cleft. The neurotransmitters then diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane of the adjacent neuron. This triggers a response in the postsynaptic neuron and allows for communication between neurons.

During exocytosis, some components are recycled. After neurotransmitter release, excess neurotransmitters in the synaptic cleft are either broken down into inactive fragments, reabsorbed through reuptake, or drift away from the synapse. Reuptake involves the neurotransmitter being pumped back into the presynaptic neuron for reuse.

The ion that is important in triggering exocytosis is calcium (Ca²+). The influx of calcium ions into the presynaptic cell leads to the fusion of neurotransmitter-containing vesicles with the presynaptic membrane, allowing for the release of neurotransmitters into the synaptic cleft.

Answer 2

1)In exocytosis: The neurotransmitter is produced, vesicles are formed around the neurotransmitters to be released and they fuse with the outer membrane of the presynaptic cell. Then, their contents (neurotransmitters) are secreted into the synaptic cleft.

2) the compounds recycled: Vesicles.
The membranes formed from old vesicles become part of the presynaptic membrane and new vesicles surge from that area of the membrane. These new vesicles are refilled with more neurotransmitters.

3)Answer: Calcium ions.
Action potentials open calcium channels that are in the membrane of the presynaptic cell, which causes the Ca+ ions to move to inside the cell . Calcium ions trigger the release of neurotransmitter from the vesicles into the synaptic cleft.