Synapses

• What is a synapse?

  A junction between neurons for signal transmission
• What role do connexins play in synapses?

  They form channels for ion flow between neurons
• What is the main type of synapse in the CNS?

  Chemical synapse
• Where are synaptic vesicles generated?

  In the presynaptic cleft
• What happens to synaptic vesicles after they move to the presynaptic terminal?

  They release transmitters into the postsynaptic membrane
• How are cells connected in an electrical synapse?

  By connexins
• What must be true for a substance to be classified as a neurotransmitter?

  It must be present in the presynaptic terminal
• What triggers the release of neurotransmitters?

  Presynaptic depolarization and Ca2+ influx
• What must be present in the postsynaptic cell for neurotransmitter action?

  Specific receptors for the neurotransmitter
• What can happen to neurotransmitters after their release?

  They may diffuse away from the synapse
• How can neurotransmitters be taken up after release?

  By specific protein transporters in cells
• What role do selective enzymes play in neurotransmitter regulation?

  They break down neurotransmitters in the synapse
• Why is it important to control the duration of neurotransmitter effects?

  To prevent prolonged signaling in the synapse
• What is an example of an excitatory neurotransmitter?

  Glutamate
• How does glutamate affect ion channels?

  It opens channels for sodium and calcium ions
• What effect does glutamate have on the cell?

  It causes depolarization of the cell
• What is an example of an inhibitory neurotransmitter?

  GABA
• How does GABA affect ion channels?

  It opens channels for chloride ions
• What effect does GABA have on the cell?

  It hyperpolarizes the cell