There is it as follows: in an aksoplazma of the terminations of neuron in close proximity to a presinaptichesky membrane by consideration under an electronic microscope the set of bubbles or was revealed, each of which contains one quantum of a mediator. The action currents caused by presinaptichesky impulses have no noticeable impact on a postsynaptic membrane, but lead to destruction of a cover of bubbles with a mediator. This process () is that a bubble, having approached an internal surface of a membrane of the presinaptichesky termination in the presence of calcium (Sa2 +), merges with a presinaptichesky membrane therefore there is a depletion of a bubble in a synoptic crack. After destruction of a bubble the membrane surrounding it joins in a membrane of the presinaptichesky termination, increasing its surface. Further, as a result of process of an endotsitoz, small sites of a presinaptichesky membrane vpyachivatsya inside, again forming bubbles which are again capable to include a mediator subsequently and to enter a cycle of its release.
Holinergicheskimi are also neurons of a spinal cord, the innervating hromaffinny cages and preganglionarny neurons, the innervating nervous cages intramuralny and ekstramuralny. Believe that holinergichesky neurons are available as a part of a retikulyarny formation of a midbrain, a cerebellum, bazalny gangliya and bark.
However, in this work, I would like to dwell upon synapses with the chemical mechanism of transfer which make the most part of the synoptic device TsNS of the highest animals and the person. Thus, chemical synapses, in my opinion, are especially interesting as they provide very difficult interactions of cages, and also are connected with a number of pathological processes and change the properties under the influence of some medicines.
- mechanoreceptors, those receptors which react to mechanical influences. They settle down in organs of hearing, balance. Tactile cages are also mechanoreceptors. Some mechanoreceptors settle down in muscles and measure degree of their stretching.
the membrane contains many calcic channels. Potential of action depolarizes the presinaptichesky termination and, thus, changes a condition of calcic channels owing to what they open. As concentration of calcium (Sa2 +) in the extracellular environment is more, than in a cage, via open channels calcium gets into a cage. The increase in the intracellular content of calcium, leads to merge of bubbles to a presinaptichesky membrane. The mediator leaves synoptic bubbles in a synoptic crack. The Sinaptichesky crack in chemical synapses quite wide also averages 10-20 nanometers. Here the mediator contacts proteins - receptors which are built in a postsynaptic membrane. Linkng of a mediator with a receptor begins a chain of the phenomena leading to change of a condition of a postsynaptic membrane, and then and all postsynaptic cage. After interaction with a mediator molecule the receptor is activated, the gate opens, and the channel becomes passable or for one ion, or for several ions at the same time.
Microelectrode researches of the last years showed that in certain interneural synapses there is an electric mechanism of transfer. Now became obvious that there are synapses, both with the chemical mechanism of transfer, and with the electric. Moreover, in some synoptic structures both electric and chemical mechanisms of transfer together function are the so-called mixed synapses.
The synapse - represents the difficult structural education consisting of a presinaptichesky membrane (most often this trailer branching an axon, a postsynaptic membrane (most often it is a site of a membrane of a body or a dendrite of another neuron, and also synoptic crack.