Download 4-6_SynTransRecycofNeurotrans_KotekZs

Zsuzsanna Kotek
Subject number: 4/6
Neptun code:KB2WMM
Synthesis,Transport and Recycling of the Neurotransmitters in general
Successful and fast communication between nerve cells is crucial and made possible by
neurotransmitters in the central and peripheral nervous system.Neurotransmitters are chemical
messengers released from neurons to communicate with another nerve cells,muscle cells or gland cells
through a synapse.The main stages of a neurotransmitter's life cycle are:
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1.Synthesis and storage: Neurotransmitters must be synthesizes and stored invesicles,so that
when an action potential arrives at the nerve ending, the cell is ready to pass it along to the
next neuron. There are two main cathegories of neurotransmitters: small-molecule
neurotransmitters, synthesised locally within the axon terminal and large peptide molecules,
synthesised in the cell body and transported through the axon to the synaptic terminal. Once
they are synthesized,in both cases with the help of synthesising enzymes,the neurotransmitters
are stored in vesicles within the axon terminal until an action potential arrives and they are
released.
2.Release: When the electric signal arrives, the neurotransmitter must be quickly and
efficiently released from the terminal and into the synaptic cleft. When the electrical signal
reaches the presynaptic terminal, it opens the voltage gated Ca 2+ channels. Once these
channels are open, calcium ions enter the presynaptic terminal. As the calcium ions encounter
the vesicles, the membrane of the vesicles fuse with the presynaptic terminal's membrane and
since their vesicles are gone, the neurotransmitters are released into the synaptic cleft.
3.Receptors: The released neurotransmitters diffuse through the synaptic cleft and reach the
post-synaptic cell where they will bind to the receptors and an action potential gets initiated.
4.Inactivation: If neurotransmitters were continually in the synaptic cleft, the postsynaptic
channels would be constantly stimulated and the membrane potential would not be able to
become stable. There are three ways in which a neurotransmitter is inactivated: being reuptaked, broken down by enzymes or can diffuse away.Transporter proteins are responsible
for the recycling,they carry the neurotransmitters back into the pre-synaptic cell, where it is repackaged into a vesicle and stored until it is once again needed, or the enzymes break them
down.
Sourses:
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http://www.interactive-biology.com/3950/the-chemical-synaptic-transmission-how-it-happens/
http://www.columbia.edu/cu/psychology/courses/1010/mangels/neuro/transmission/transmission.html
https://users.itk.ppke.hu/neurobiologia/LECTURES_20162017_SEMESTER_1/4.%20WEEK/1.%20HANDOUT/Neurob_12.pdf
https://web.williams.edu/imput/synapse/index.html
https://en.wikipedia.org/wiki/Neurotransmitter
https://en.wikipedia.org/wiki/Neurotransmission
https://www.youtube.com/watch?v=VitFvNvRIIY
https://www.youtube.com/watch?v=-L4OrTQLVRw
https://www.ncbi.nlm.nih.gov/books/NBK10960/
http://what-when-how.com/neuroscience/neurotransmitters-the-neuron-part-1/
https://users.itk.ppke.hu/neurobiologia/LECTURES_20162017_SEMESTER_1/4.%20WEEK/3.%20LITERATURE/Synapses.pdf
http://faculty.pasadena.edu/dkwon/chap%208_files/textmostly/slide63.html