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Chapter 3.
What are neurons?
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Neurons are conducting cells of the nervous system.
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Define:
Soma (Cell Body) Dendrites Axon |
Soma: Contains genetic information to determine cell function
Dendrites: Receives messages from other neurons Axon: Conduct electrical impulses |
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What are the functions of a glial cell?
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Support, nourish, protect
Surrounds cells to protect them
Manufacture nutrients that neurons need Absorb toxins and waste materials |
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What is the resting potential and neutrons and the ions on the outside and inside?
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-70 millivolts
outside: Na+ (Sodium) inside: Ka+ (Potassium) |
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What are graded potentials?
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Changes which are proportional to stimulation.
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What is the "All or None" Law?
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Action potential not proportional. Fires with maximum intensity or none at all.
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What stimulates the dendrite?
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The axon.
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What happens during depolarization?
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Ion channels open and allows Sodium to flow in.
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What happens with the action potential?
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Depolarization reaches -55 millivolts.
Fires according to the all or none law. |
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What is the Myelin Sheath and its purpose?
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Fatty insulin layer derived from the glial cells. It increases the rate of transmission signals and protects the axon from electrical activity.
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What are the Nodes of Ranvier and their purpose?
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They are gaps in the myelin sheath and it signals jump from one gap to another.
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What is multiple sclerosis?
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When the immune system attacks the myelin sheath.
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How do Neurons communicate?
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By synaptic transmissions. They do not physically contact. They use chemicals.
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What is the synaptic cleft?
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The gap between the axon terminal and dendrite
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What do excitatory neurotransmitters do?
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Depolarize neuron. Stimulates flow of sodium. Increases likelihood of action potential.
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