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Schwan cell
Diagram from: http://commons.wikimedia.org/wiki/File:Anatomy_and_physiology_unlabeled_neuron.jpg
The Motor Neuron
nerve impulse
http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf
Membrane 50 times more permeable to K+ ions than Na+
Proteins inside the nerve fiber are negatively charged which increases the charge imbalance.
-70mV
http://www.blackwellpublishing.com/matthews/channel.html
From McGraw Hill: http://goo.gl/tI2MD
http://www.blackwellpublishing.com/matthews/actionp.html
http://outreach.mcb.harvard.edu/animations/synaptic.swf
Acetylcholine
• Neurotransmitter in many synapses• Produced in pre-synaptic neuron, loaded into
vesicles & released into synaptic cleft during synaptic transmission.
• Receptors located in post-synaptic membrane• While bound, one action potential is initiated.• After transmission it breaks down.
Threshold potential
• Action potentials only initiated if threshold potential is reached
• At synapse, the amount of neurotransmitter secreted following depolarization of the pre-synaptic membrane may not be enough to cause t.p. to be reached in post-synaptic membrane.
• Depolarization does not take place. Returns to resting potential
• Neurons in brain & spinal cord have many pre-synaptic neurons. Often multiple must secrete neurotransmitters at same time.
neonicotinoids
• Synthetic compounds similar to nicotine• Bind to acetylcholine receptor in the central
nervous system of insects.• Binding is irreversible, permanently blocking
receptors resulting in paralysis and death• Advantage in pesticides: not toxic to humans or
mammals. • Disadvantages: effects on honeybees and other
beneficial insects.
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