Nerve Impulse Transmission - Essay Example

Role of Synapses in Nerve Impulse Transmission s Synapse plays a great role in transmission of nerve impulses between cells, as it is literally the place of contact between the two neurons or a neuron and a recipient cell. Transmission of impulses is typically enabled chemically with help of mediators or electrically by the ions’ passing from one cell to another. While neurons are cells passing neural signals to target cells, synapses are the conjunctions between neurons enabling transmission.

Thereby, each neuron has a great numbers of synapses on its surface, which can reach 10000. A typical chemical synapse consists of two parts: presynaptic (which is the plasma membrane of the neuron that passes a signal) and postsynaptic (the membrane of a recipient, target neuron). These two parts are separated by the synaptic cleft, a small gap (10-50 nanometers wide), with cell junctions on both ends of it. The part of the neuron’s axon terminal belonging to the synaptic cleft is called presynaptic membrane, while the area of the target cell limiting the cleft on the opposite side is called postsynaptic membrane, which typically contains multiple receptors.

Axon terminal of the passing cell contains synaptic vesicles, tiny bubbles with neurotransmitter. Thereby, neurotransmitter can be of two main types: inhibitory and excitatory, whereby excitatory neurotransmitter is the chemical mediator enabling transmission of the impulse and inhibitory neurotransmitter is a ferment dissolving this mediator. Postsynaptic membranes of the target cells have receptors sensitive to different neurotransmitters. The process of synaptic neurotransmission is extremely fast and relies on the following factors: availability of neurotransmitter and its timely release from the synaptic vesicles, binding effect of neurotransmitter on the receptor located in the postsynaptic membrane, response of the target cell with the subsequent deactivation or removal of the used neurotransmitter.

The process of synaptic transmission on its initial stage is activated by action potential, which is the “electrical signal generated near the cell body of a neuron” (Stufflebeam, 2008). Once these signals are generated near the body of a presynaptic cell, they spread to the axon terminal and trigger release of neurotransmitter from the synaptic vesicles (Wang et al., 2009, p.1). Neurotransmitter released from the synaptic bubble moves across the synapse and synaptic gap until it is detected by and binds with the sensitive receptors of the postsynaptic membrane.

The effect produced in the postsynaptic neuron after binding with neurotransmitter depends on the type of the latter – either inhibitory or excitatory. The neurotransmitter has a very short-term effect, whereafter it is dissolved by a specific ferment as soon as it completes its task. Furthermore, it is necessary to mention that the type of the synapse – inhibitory or excitatory depends on the type of neurotransmitter contained in the axon terminal. For instance, some mediators such as glutamate are typical only for excitatory synapses, while gamma-aminobutyric acid is a typical mediator of inhibitory synapses.

Thereby, binding of chemical neurotransmitters to the receptors of the target neurons might result in short-term changes such as change of membrane potential or in long-term changes that are triggered once signaling cascades are activated. Effect of synaptic neurotransmission is believed to be significant for memory formation. Thereby, the storage of information is preconditioned by the effect of neurotransmitters on the receptors within the synaptic gap and strengthening the bond between two cells.

When both presynaptic and postsynaptic neurons and active simultaneously due to signaling mechanisms of the receptor, the information is stored and memory is formed. Reference list:Stufflebeam, R. (2008). Neurons, Synapses, Action Potentials, and Neurotransmission. Consortium on Cognitive Science Instruction. Retrieved June 29, 2015 from: http://www.mind.ilstu.edu/curriculum/neurons_intro/neurons_intro.phpWang, L., Fedchyshyn, M. J., & Yang, Y. (2009). Action potential evoked transmitter release in central synapses: Insights from the developing calyx of Held.

 Molecular Brain,2. doi:10.1186/1756-6606-2-36