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W HAT N EURONS H AVE IN C OMMON W ITH O THER C ELLS Plasma membrane External wall of the cell Forms a boundary between internal and external environment Double layer of lipids Gates Defines boundary of the cell Detects substances Selectively permeable 3
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Brain and BehaviorNeurons
01.21.2016
WHAT ARE NEURONS?
• Cells transmitting info in the nervous system
• Neurons exist in circuits Group of neurons connected in a precise,
directionally oriented pathway
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WHAT NEURONS HAVE IN COMMON WITH OTHER CELLS
• Plasma membrane External wall of the cell Forms a boundary between internal and external
environment Double layer of lipids Gates
Defines boundary of the cell Detects substances Selectively permeable
3
WHAT NEURONS HAVE IN COMMON WITH OTHER CELLS
• Cytoplasm = material enclosed by plasma membrane
• Cytoplasmic Organelles (“little organs”) Mitochondria
• Energy source for cell
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Ribosomes Place where proteins are
produced Endoplasmic
Reticulum (ER)• Synthesis, storage,
transport, evacuation of molecules
• E.g. Golgi Apparatus• Rough ER – produces protein• Smooth ER – produces lipids
and steroids
WHAT NEURONS HAVE IN COMMON WITH OTHER CELLS
• Golgi Apparatus• Type of Smooth ER• Produces lysosomes• Breaks down substances no longer needed in the
neuron• Package synaptic vesicles • Released in terminal buttons
WHAT NEURONS HAVE IN COMMON WITH OTHER CELLS
WHAT NEURONS HAVE IN COMMON WITH OTHER CELLS
• Nucleus Located at center of main body of cell Location of genetic information DNA=contains genetic instructions in development and
functioning of the organism RNA=transmit genetic information from DNA outside
nucleus for protein production
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UNIQUE FEATURES OF NEURONS:THE AXON
• Means of transmitting information (nerve impulses)• The brain has ~100billion neurons
• The axon SENDS information from the cell body to other neurons
• Axon terminal End of axon
• One axon per cell But, may have collateral axons
• Branches of the axon
• Allow communication with multiple cells8
STRUCTURE OF NEURONS
Colla
tera
l ax
ons
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THE UNIQUE FEATURES OF NEURONS:THE DENDRITES
• Protrude from cell body (soma)• Dendrites RECEIVE information from other
neurons• Dendrites + Soma
= Receiving zone for incoming messages
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STRUCTURE OF NEURONS
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STRUCTURE OF NEURONS
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Synapse• Synapse - Small gap between axon
terminal of Neuron A and dendrites/cell body of Neuron B
• Terminal buttons – at the end of axon branches• Secrete chemicals (NT’s) when action potential reaches
them
HOW ARE NEURONS CLASSIFIED?
• Sensory neurons AFFERENT neurons Receive sensory signals from sensory organs Send signals via short axons to CNS Unipolar/pseudo-unipolar neurons – one branch
is the axon, the other is the dendrite
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HOW ARE NEURONS CLASSIFIED?
• Motor neurons EFFERENT neurons Conduct motor commands from the cerebral
cortex to the spinal cord, or from the spinal cord to the muscles
Multipolar neurons – several short dendrites and one long axon
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HOW ARE NEURONS CLASSIFIED?
• Interneurons• Connect different neurons within the brain or spinal
cord• Bipolar neurons – two main extensions: axon and
dendrite
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OTHER CELLS & STRUCTURES OF THE NERVOUS SYSTEM: GLIAL CELLS
• There are two types of cells in the nervous system: • Neurons• Glial Cells
• Specialized support cells• Found in space between the nerve cells• General function: “housekeeping”• Produce myelin, covers axons
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OTHER CELLS AND STRUCTURES OF THE NERVOUS SYSTEM: GLIAL CELLS• Astrocytes
Most common type of glial cell
Primary function• “Clean up” excess neurotransmitters and ions from
extracellular space
Other functions• Support active areas with extra energy
• Clean up dead neurons after injury18
OTHER CELLS AND STRUCTURES OF THE NERVOUS SYSTEM: GLIAL CELLS• Myelination
Provided by glial cells• Wrap themselves around axons of neurons
Allows for rapid transmission of impulses
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OTHER CELLS AND STRUCTURES OF THE NERVOUS SYSTEM: GLIAL CELLS• What glial cells provide the myelin?
In central nervous system Oligodendrocytes
In peripheral nervous system Schwann cells
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