1) Describe the process of chemical synaptic transmission, starting with depolar
ID: 200252 • Letter: 1
Question
1) Describe the process of chemical synaptic transmission, starting with depolarization of the presynaptic terminal and ending with neurotransmitter binding to the postsynaptic neuron. Make sure you discuss in detail the role of calcium in this process-how it enters the neuron, and what it acts upon. 2) Signaling by second messengers is an essential component of synaptic communication. a) What type of neurotransmitter receptors utilize second messengers in their signaling. b) Name two second messengers and a specific target that they can activate. c) describe how a second messenger can trigger the release of another second messenger -be specific. 3) Execution by lethal injection involves administration of the following drugs, in order: Sodium thiopental which activates ionotropic GABA receptors Tubocurarine chloride which blocks AChR Potassium chloride, which increase Extracellular Potassium levels. a) For each, describe the effect this drug would have on electrochemical signaling and the effects on the postsynaptic neurons. b) Suggest an invention that could reverse the effects of two of these three drugs.Explanation / Answer
Neurons are the specialized cells that help in conducting the electrical information in the body. The neurons synapse on each other to accomplish the process of conducting electrical information. The point where two neurons synapse, a gap left between both neurons which, is called as synaptic cleft. There are five steps in which, chemical synaptic transmission occur.
Step 1: Synthesis of neurotransmitter
Small amino acids and large neuropeptides are the two classes of neurotansmitters. The synthesis of large neuropeptides take place in the cell body of the neuron. These large peptides are transported through the axon to the synaptic terminal. Presynaptic terminal is the site where small amines generally be synthesized.
The whole process begins as the action potential travel along the presynaptic cell membrane till it come along the synapse. The channels at the synapse get open due to the membrane depolarizaton. These channels are permeable to calcium ion. The flow of calcium ion occur through the presynaptic membrane that increase the concentration of the calcium in the interior.
A set of calcium-sensitive protein which, is attached to the vesicles get activates through the high concentration of calcium ions. These vesicles have neurotransmitter chemical. The neurotransmitter diffuse with the cleft and absorbed by the presynaptic cell and repackaging occur for the future release.
step 2 and 3: Neurotransmitter packaging and release
As soon as there is a synthesis of neurotransmitters, they need to be put in the small groups to launch across the synaptic cleft. The packaging occur into the vesicles. As soon as the neurotransmitters receives the order from Ca 2+ ions the small group of neurotransmitters released into the synaptic cleft. The channels get open when electrical signal reaches the presynaptic terminal.
The surrounding Ca ions also rush into the presynaptic terminal as the channel opens. The binding of calcium ion occur with the synaptotagmin proteins. These proteins found in the membrane of the synaptic vesicles. The fusion of vesicles with the presynaptic membrane also occur due to this binding. The vesicles fuse with the membrane of the presynaptic terminal as soon as they encounter the calcium ion. This process occur at the synaptic cleft. The neurotransmitters expelled into the synaptic cleft as the vesicles fuse with the membrane.
Step 4: Neurotransmitter binding
To reach the postsynaptic neuron, the neurotransmitters diffuse through the synaptic cleft. There are few channels presents on the postsynaptic neuron membrane that control the translation of neurotransmitters into the electrical signal. This process take place by changing the local transmembrane potential.
Step 5: Termination
After the translation of neurotransmitter into the electrical signal the postsynaptic receptor must be cleared very quickly. This is necessary to receive the new transmitters from the new signals. Few of the neurotransmitters get degrade, some get transported back to recycle, and some absorbed by the postsynaptic terminal.
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