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Chapter 8: Synaptic Transmission and neural Integration
Morphine – a product of opium poppy relieves pain because it can bind to certain
neurons in a CNS at receptors for naturally occurring morphine like messenger
molecules- Enkephalins and Endorphins. Thus morphine suppresses the
transmission of pain signals.
Chemical messenger acts by binding to a receptor.
NT bind to postsynaptic neuron.
2 Types of synapse in Nervous System:
1. Electrical synapses – via gap junctions that link two cells electrically (by
2. Chemical Synapses - synapse where a neuron secretes a neurotransmitter
(activate signal transduction mechanism ) into the extracellular fluid in
response to an action potential arriving at the axon terminal
Exist bet. Neurons and bet. Neurons and glial cells. Plasma membrane of
adjacent cells are linked by gap junctions
Junctions transmit signal in the adult brain
Communication maybe bidirectional or unidirectional in gap junctions.
Comm. Can be excitatory or inhibitory at the same synapse (depol.or
Majority of synapses in nervous system
1 neuron secretes NT into ECF …. Df. NT binds to receptors in plasma
membrane of a 2bd cell triggering elec.signal may or may not initiate AP
Effector organs – muscles and glands
Neuroeffector junction - synapse bet.neuron and effector cell
Non-neuronal cells can form synapses w/neurons e.g. taste receptor cells in
Functional Anatomy of Chemical Synapses
Neuron-neuron synapses, close junctions bet.axon terminal of 1 neuron and plasma
memb. Of another neuron.
Presynaptic neuron - at a synapse, a (first) neuron that transmits signals to a
second neuron or an effector cell
Postsynaptic neuron – 2nd neuron that receives signal from first
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