Transcript Synapses
Excitatory A/P The origin of an action potential Leads to an action potential in the post-synaptic neuron At the axon hillock The origin of an action potential Does not lead to an action potential in the post-synaptic neuron Inhibitory A/P The origin of an action potential Excitatory The two types of potential can cancel each other out… the process of adding up all incoming potentials is called synaptic integration Inhibitory At the end of an action potential, what happens? Synaptic Transmission • Electrical signals are changed into chemical signals through process called exocytosis • Exocytosis is a process in which an intracellular vesicle (membrane bounded sphere) moves to the plasma membrane and subsequent fusion of the vesicular membrane and plasma membrane ensues. Following an action potential: Neurotransmitters will be released in the synaptic cleft and influence the post-synaptic neuron… Need to get through the membrane Exocytosis The pre-synaptic terminal at rest Action potential arrives Influx of calcium Different types of postsynaptic neurotransmitter receptors Ionotropic Metabotropic Ionotropic: The receptor binds and performs as a gate for ions Metabotropic: The receptor binds and links to G-protein G-protein coupled receptors (metabotrophic receptors). Ionotropic Fast, but weak Metabotropic Slow, but strong How do drugs influence synaptic transmission? Cocaine blocks the NET A synapse that uses norepinephrine (NE) Fluoxetine/Prozac blocks the SERT A synapse that uses serotonin/5-HT Agonists • drugs that increase or mimic the effect of a neurotransmitter Antagonists • a drug that decreases or block the effect of a neurotransmitter