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Published on 24 May 2011
School
UTSG
Department
Biology
Course
BIO220H1
Professor
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 synapsesvia gap junctions that link two cells electrically (by
electrical signals)
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
Electrical Synapses
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
hyperpol.)
Chemical Synapses
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
tastebuds
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 neuron2nd neuron that receives signal from first
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Document Summary

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. 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. Can be excitatory or inhibitory at the same synapse (depol. or hyperpol. )  1 neuron secretes nt into ecf . Nt binds to receptors in plasma membrane of a 2bd cell triggering elec. signal may or may not initiate ap.  neuroeffector junction - synapse bet. neuron and effector cell.  non-neuronal cells can form synapses w/neurons e. g. taste receptor cells in tastebuds. Neuron-neuron synapses, close junctions bet. axon terminal of 1 neuron and plasma memb.