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BIOL 1104: Test 3
Neuron
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Specialized cells that can receive and transmit chemical or electrical signals
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Glia
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Cells that provide support functions for the neurons by playing an information processing role
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Dendrites
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Tree-like structures that extend away from the cell body to receive messages from other neurons at specialized junctionsÂ
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Synapses
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Specialized junctionsÂ
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Axon Hillock
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Specialized estruture within the cell body that integrates signals from multiple synapses and serves as a junction between the cell body and an axon
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Axon
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Tube-like structure that propagates the integrated signal to axon terminals
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Axon Terminals
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Specialized endings that synapse on other neurons, muscle or target organs
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Nodes of Ranvier
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The periodic gaps in the myelin sheath of the axon(s)
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Types of Neurons
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Unipolar
Bipolar
Multipolar
Pseudounipolar
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Unipolar Neurons
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Only have one structure that extends away from the soma
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Bipolar Neuron
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Has one axon and one dendrite extending from the soma
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Multipolar Neurons
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Has one axon and multiple dendrites
Is the most common type of neuron - found in the central nervous system
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Pseudounipolar Cells
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Has a single process that extends from the soma but later branches into two distinct structures.
Most sensory neurons are this
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Types of Glia
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Astrocytes
Satellite
Micro-
Oligodendrocytes
Radial
Ependymal
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Astrocytes
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Provide nutrients and other substances to neurons, regulate the concentrations of ions and chemicals in the extracellular fluid, and provide structural support for synapses.
Form the blood-brain barrier
Makes contact with both capillaries and neurons in the CNS
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Satellite Glia
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Provide nutrients and structural support for neurons in the PNS
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Microglia
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Scavenge and degrade dead cells and protect the brain from invading microorganisms
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Oligodendrocytes
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Form myelin sheaths around axons in the CNS
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Radial Glia
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Serves as scaffolds for developing neurons as they migrate to their end destinations
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Ependymal Cells
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Line fluid-filled ventricles of the brain and the central canal of the spinal cord
Involved in the production of cerebrospinal fluid, moves the fluid between the spinal cord and the brain, and is a component for the choroid plexus
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Membrane Potential
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The difference in total charge between the inside and outside of the cell
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Steps of an Action Potential
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1. A stimulus from a sensory cell or another neuron causes the target cell to depolarize toward the threshold potential
2. If threshold is reached, all Na+ channels open and the membrane depolarizes
3. At the peak, K+ channels open and K+ begins to leave the cell; Na+ channels close
4. Membrane becomes hyper polarized as K+ ions continue to leave the cell; membrane is now in refractory period
5. The K+ channels close and the Na+/K+ pump restores the resting potential
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Saltatory Conduction
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The 'jumping' of the action potential from one node to the next
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Presynaptic Neuron
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Neuron transmitting the signal
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Postsynaptic Neuron
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Neuron receiving the signal
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Types of Synapses
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Chemical
Electrical
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Synaptic Vesicles
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Small membrane-bound __ containing neurotransmitter molecules to fuse with the presynaptic membrane
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Synaptic Cleft
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The extracellular space between the presynaptic and postsynaptic membranes
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Effects on the Postsynaptic Membrane
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Excitatory Postsynaptic Potential (EPSP)
Inhibitory Postsynaptic Potential (IPSP)
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Summation
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Process of sufficiently depolarization to fire an action potential
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