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7-Synatic Transmission 1 Figs BW

Important the connexon of one membrane is precisely

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Unformatted text preview: mportant: the connexon of one membrane is precisely align to the connexon of the next membrane, so that the water-filled pore (channel) directly perforate both membrane directly, going from intracellular fluid of one cell to another. these gap junctions channels are bi-directional. they readily pass current and small organic molecules in both direction. Again, commonly found in cells whose electrical or metabolic activity need to be coordinated. this happen a lot during in embryonic development where lots of adjacent cells are connected via gap junctions. this is important in passage of secondary messenger or multiple genetic signal from cell to cell. At some point in development, gap junction cease to be express, they are remove from membrane and cell within tissue become metabolically isolated from one another. there are some regulations of the permeability or conductance of gap junction channels. gap junction channels are subject to negative regulation by calcium ion or hydrogen ion (proton), either in increase in intracellular calcium ion or intracellular proton (drop in pH) will close the gap junction channels. 2. chemical Post- Channels may close in response to: ↑ [Ca2+]in ↑ [H+]in Connexin Connexon Negative stain EM of gap junction Presynaptic membrane 3 nm Postsynaptic membrane Gap junctions (green) between cardiac cells Current exiting connexon channel Steps in Chemical Synaptic Transmission the next is chemical synaptic transmission. chemical is more ubiquitous in vertebrae nervous system. -information is going left to right. 1. the first step is synthesis of transmitter. the neural transmitter, T, is enzymatically synthesized from a precursor molecule P within pre-synaptic terminal. this apply to all neural transmitter except peptide neurotransmitter. this means that all neurotransmitter are synthesized locally within presynaptic terminal. everything involve in synthesis is contain within the terminal. for peptide it's different because only in soma of neuron locate the machinery of ribosome, golgi necessary for synthesis and modification of peptide and proteins. in th...
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