Synaptic transmission and how drugs may modify this activity essays

Synaptic transmission and how drugs may modify this activity essays Discuss the mechanism of synaptic transmission and how drugs may modify this activity. Synapses are crucial to the function of the nervous system. The majority of the synapses in the nervous system in vertebrates are chemical synapses, where chemicals are used to transmit information between cells; however there are also some electrical synapses (Carlson 2004, Sjaastad et al. 2003). The cells in smooth musculature and cardiac musculature are electrically connected through gap junctions which are exceptionally large protein channels forming membrane pores extending from cell to cell, enabling small molecules and ions to move freely between the cells (Sjaastad et al. 2003). But nevertheless, the majority of the synapses in vertebrates are chemical. Mechanism of chemical synaptic transmission When a nerve impulse reaches a chemical synapse, neurotransmitters, which are signal molecules, are released from the nerve terminal and diffuse to the membrane of the target cell (Sjaastad et al. 2003). The target cell contains receptor molecules where the neurotransmitters bind, and this binding will results in changes in the membrane potential, and will excite or inhibit the electrical activity of the target cell (Sjaastad et al. 2003). In the pre-synaptic cell, you can find small vesicles containing the synthesized neurotransmitters, and the action potential will cause an influx of Ca2+ through voltage-gated calcium channels, fusing the vesicle membrane with the presynaptic membrane causing a release of the neurotransmitter into the synaptic cleft (Carlson 2004, Sjaastad et al. 2003). The neurotransmitter will diffuse across the synaptic cleft, and when the neurotransmitters bind to the postsynaptic receptors, these receptors will open neurotransmitter-dependent ion channels (Sj aastad et al. 2003). There are at least two different ways of opening these channels: directly and indirectly (Carlson 2004). In the direct method, the ion channel ...