BIO310H5 Lecture Notes - Lecture 5: Electrical Synapse, Chemical Synapse, Gap Junction
Document Summary
Bio310 lecture 5: neurons use electrical and chemical mechanisms to communicate information to another cell, synapse; anatomically specialized junction (15-60mm) between neurons and cells - it is the functional contact. Synapse: the two types of synapses in the nervous system. Direct flow of electrical current from one cell to the next through gap junctions. Chemical (how most signalling between neurons occurs) Electrical and chemical synapses: current flow at electrical synapses. (b) in chemical synapses, the currents escape between neurons and do not enter the postsynaptic neuron. The molecular structure of electrical synapses: gap junction. A connexon is composed of six identical connexin proteins (transmembrane proteins). Chemical synapses: synaptic vesicles contain neurotransmitter. The arrival of action potential in axon terminal opens ca2+ channels. Ca2+ triggers vesicle fusion and transmitter release. Neurotransmitter can bind to ionotropic receptors, opening their ions channels. A vertebrate neuromuscular junction: the neuromuscular junction consists of a single presynaptic motor neuron contacting a single postsynaptic skeletal fiber b.
