Nervous System:
Neurotransmitters and
Neural Synapses
By Idan Waksman, Rey Duran and Kyle Johnston
Chemical Synapse and
Neurotransmitters
-When action potentials
(electrical impulses)
reach the presynaptic
neuron output zone,
the axon, they may
trigger the neuron to
release one or more
neurotransmitter,
which goes through the
chemical synapse and
then into the
postsynaptic neuron
called the dendrite. (2)
ELECTRICAL AND CHEMICAL
SIGNALS
- The synaptic cleft, a divide
between two neurons only a
few nanometers wide, is a
barrier for the electrical
signal carried by one neuron
to the other. Think of an
electrical circuit; the
synaptic cleft would be
considered a “short” (1).
- The electrical signal traveling
down the presynaptic
neuron cannot cross the
fluid-filled synaptic cleft.
Chemical neurotransmitters,
however, can (1).
Chemical Synapse and
Neurotransmitters (cont.)
-The calcium ions then flow inside the cell and down the
gradient, which causes the release of neurotransmitters
into the synaptic cleft. (2)
-Neurotransmitters are chemicals that transmit signals
from a neuron to a target cell across the synapse.
-They become released into and diffuse across the
synaptic cleft, through exocytosis. (3)
Chemical synapse animation
Histamine and Dopamine; 2
examples of specific
neurotransmitters
-Histamine is an organic nitrogen compound
involved in local immune responses. It also
regulates physiological function in the gut
and acts as a neurotransmitter. It is located
in the stomach lining. (5)
-Dopamine is a neurotransmitter in the brain
that affects a variety of different behaviors.
The major areas it affects include
movement, cognition, and motivation.
Crossing the Neural Membrane
-When the neurotransmitters arrive at the
input zone of an adjacent neuron, they
attach to the proteins and send a message
for the proteins to open. (4)
Here is a Fun Video!
How does this happen?
- At the presynaptic ending, the action potential causes
the vesicles containing neurotransmitters to bind to the
membrane. They fuse and release the neurotransmitters
into the synaptic cleft in exocytosis (3).
- Ions carry the electrical charge through the neuron. In
chemical neurotransmission, a specific neurotransmitter
binds to the receptor site on the postsynaptic neuron,
causing the ion channel to open and allowing the ions to
cross the membrane(1).
Animation
REFERENCES
1. Stufflebeam, Robert. "Neurons, Synapses, Action Potentials, and
Neurotransmission."The Mind Project. Illinois State University, 2008. Web. 02 Nov.
2012. <http://www.mind.ilstu.edu/curriculum/neurons_intro/neurons_intro.php>.
2. "How Neurotransmission Works." The Brain: Understanding Neurobiology. National
Institute of Health, 2010. Web. 3 Nov. 2012.
<http://science.education.nih.gov/supplements/nih2/addiction/activities/lesson2_neuro
transmission.htm>.
3. Chudler, Eric C. "The Synapse." Neuroscience for Kids. University of Washington,
2012. Web. 05 Nov. 2012. <http://faculty.washington.edu/chudler/synapse.html>.
4. Starr, Cecie, and Ralph Taggart. Biology: The Unity and Diversity of Life. 9th ed. N.p.:
Thomson Learning, 2001. Print.
5. "Histamine." ScienceDaily. ScienceDaily LLC, n.d. Web. 05 Nov. 2012.
<http://www.sciencedaily.com/articles/h/histamine.htm>.