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Neurotransmitters and synapses. IB Biology Jin Young Huh. Excitatory and inhibitory synapses. Two main types of synapses: Excitatory synapses Inhibitory synapses. Excitatory synapses. The neurotransmitter is released by the presynaptic neuron
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Neurotransmitters and synapses IB Biology Jin Young Huh
Excitatory and inhibitory synapses • Two main types of synapses: • Excitatory synapses • Inhibitory synapses
Excitatory synapses • The neurotransmitter is released by the presynaptic neuron • The neuron causes sodium ions or other positively charged ions to enter the postsynaptic neuron • Depolarize neuron and cause an action potential • Postsynaptic transmission- excited (stimulated)
Inhibitory synapses • Neurotransmitter causes negatively charged chloride ions to move into the postsynaptic neuron • Increase its polarization (hyperpolarization) • Postsynaptic transmission- inhibited
Decision- making in the CNS • Synapses are the sites at which decisions are made • A rapid sequence of pulses of neurotransmitter is needed