Question

Describe how synaptic potentials show electrotonic characteristics.

      Describe the molecular basis of vesicle release of neurotransmitter listing and defining the roles of molecules involved.

Answer 1

Synapse is the junction between the axon of one neuron and dendrite of another neuron or the target organ. These neurons communicate with the help of chemical mediators called as “neurotransmitters,” they are known as “chemical synapses.”

Graded potentials are generated with any change in the ion concentration within in the cell, they occur when the axon is stimulated to some extent. If the graded potentials cause depolarization of the membrane, then EPSP (excitatory postsynaptic potential) is generated. If the graded potential cause hyperpolarization of the postsynaptic membrane, then IPSP (inhibitory postsynaptic potential) is generated.

The neurotransmitters are present in the storage vesicles of the nerve terminals. These are the sac-like structures that are formed from the layer of the cell membrane. If the action potential reaches the nerve terminals, the neurotransmitters the voltage-gated calcium channels are activated.

The influx of calcium ions causes “exocytosis,” through which the stored neurotransmitters are released from the synaptic vesicles. The released neurotransmitters allow the synaptic transmission, i.e. the transmission of an impulse from one neuron to the other neuron or effector organ via the synapse.