Q) Describe synaptic transmission
Main points | |
Key idea: | What is a synapse |
· A junction b/w two neurons or b/w a neuron and and effector (muscle or gland) for the purpose of transfering information | |
Key idea: | Role of Ca2+ |
· Initially, little amount of Ca2+ in synaptic knob · Arrival of an action potential (AP) depolarizes pre-synaptic membr, Ca2+ channels open, influx of Ca2+ into synaptic knob, synaptic vesicles fuse with pre-synaptic membr, release neurotransmitters (e.g. acetylcholine) into synaptic cleft · Neurotransmitters diffuse a/x synaptic cleft, bind to receptor-linked ion channels on postsynaptic membr · Ion channels open, influx of Na2+ into post-synaptic neurone, depolarizes post-synaptic membr, generates AP if threshold value is reached | |
Key idea: | Breakdown and synthesis of acetylcholine |
· Acetylcholinesterase breaks down acetylcholine into choline + acetate · Return to synaptic knob, re-form acetylcholine + re-packed into synaptic vesicles · Removal of acetylcholine causes postsynaptic membr to repolarize | |
Comments: (i) Visualize the answer with the aid of a labelled diagram. (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) Deplorization of post-synaptic membrane is weak; requires temporal or spatial summation of excitatory potentials (v) The transmission of a nerve impulse across a synapse is slower than the transmission of a nerve impulse (propagation of action potential) along the axon. Compare and contrast between these two types of transmission | |
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