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The Brain Theory

Neurons & Synaptic Transmission

Introduction
Summary
CNS
Guestbook
Basic Facts
4 Quad Model
Brain Links
Triune Theory
Left vs. Right
Neurons & ST
References

• neurons are the functional units of the nervous system that are responsible for transmitting & receiving messages
 
the three types of neurons are sensory neurons, motor neurons, & interneurons (see Basic Brain Facts)
 
• all neurons contain dendrites (receive), cell bodies, & axons (project)
 
• synapses is the term used to describe the connection between neurons
-"a single neuron may branch many times at its end plate and join with many different neurons" (Di Guiseppe 423)
 
• neurotransmitters (see Basic Brain Facts) are released from the end plate of the axon to transmit impulses and signals
 
• like enzymes in our bodies, neurons respond to changes in pH, pressure, as well as to certain chemicals
 
Synaptic Transmission (shown below in Figure 5)
1) action potentials travel from the cell body to the end of the axon of that neuron; each axon terminal is swollen forming a synaptic knob
2) the synaptic knob is filled with neurotransmitters.
3) arrival of an action potential at the synaptic knob opens Ca2+ channels in the plasma membrane
4) the influx of Ca2+ triggers the exocytosis of some of the vesicles
5) these neurotransmitters are then released into the space between the projecting axon & receiving dendrite/cell (synaptic cleft) 
6) the neurotransmitter molecules bind to receptors on the postsynaptic membrane of the responding dendrite or cell
(Kimball)
 
Figure 5: Synaptic Transmission between Neurons (Kimball)