BIOLOGY 2A03 Lecture Notes - Lecture 7: Axon Terminal, Neurotransmitter Receptor, Myelin
Document Summary
Does not mean all vertebrates have myelinated axons. Metabolically cheaper - aps occur only at nodes so voltage-gated channels and na+/k+ - Saves space and resources - axons can be much thinner for given conduction velocity. Hodgkin and huxley discover mechanisms of ap generation. Studied giant axons in squid mantle (largest known in animal kingdom) Allows things (i. e. channels) to be localized to nodes of ranvier. Saves energy in protein production by making channels localized. Stronger, longer-lasting graded potentials (i. e. stronger stimuli) produce more action potentials (higher frequency) Larger stimuli will more likely generate an ap during the relative refractory period, so frequency is higher. Can be found at axon terminal or along (axon varicosities) Synaptic cleft - space between pre- and post-synaptic terminals (20-50 nm) Most common type of synapse = axodendritic synapse. Axosomatic synapse - cell body forms synapse with axon terminal. Axoaxonic synapse - axon forms synapse with that start of another axon.