3. Using the diagram of the synaptic inputs below, assume E1 and E2 release the

Question

3. Using the diagram of the synaptic inputs below, assume E1 and E2 release the same amount of neurotransmitter and that the same number of receptors are located on the synaptic membrane for both of these synapses. Alone, neither causes an action potential, but together they can if they occur within 2ms of eachother. Stimulation of I can prevent an action potential if it occurs within 1ms of an excitatory pulse. Excitatory ( Postb ynaj Inhibitory potential Excitatory (E2) Threshold -40 Cell body Dmdribs -110 023423 Time (m Axon a. What kinds of ion channels are likely opened by E and I, explain your answer

Explanation / Answer

E1 and E2 are excitatory nerve signals that can only form an actions potential together. All EPSP are excitatory postsynaptic potential caused by depolarization of membrane. Depolarization of membrane is due to opening of ligand gated sodium channels. As sodium ions flow into the cell, the cell become less negative on the inside. Multiple excitatory signals are required for generating action potentials.

If there is a negative neurotransmitter released, there is potassium ions released on outside of the cell due to opening of ligand gated potassium channels. This allows the cells to become more negative inside the cell causing hyperpolarization of the membrane. This is known as a Inhibitory Postsynaptic Potential (IPSP) resulting in no action potential. IPSP can also result due to opening up of ligand-gated Chloride Ion channels, that allows chloride to flow into the cell.

Glutamate receptors can be ionotrophic or metabotropic glutamate receptors. In excitatory impulses, the ionotropic glutamate receptors (ligand gated sodium ions channels) open to allow sodium to flows in the cells. Depolarization causes an action potential ito be generated. Glutamate is the precursor of gamma amino butyric acid. In B, GABA synapse is activated, there will be hyperpolarization of membrane. This is due to opening of potassium channels due to metabotropic G protein glutamate that are linked to potassium channels. These open leading of influx of potassium ions outside the cells. As a result, the membrane potential becomes more negative (-70mV as shown in B).

According to second, figure, Na ions channels are opened by the excitatory E and potassium channels are opened by I. However, I can also open potassium channels, if they are activating ionotrophic receptors.

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