The Nervous System
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Transcript of The Nervous System
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The Nervous System
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Review: What makes up the Nervous System?
• The brain• Spinal cord• Nerves• 2 types of cells: – neurons: send and receive signals– glial cells: protect, support, and insulate neurons
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Review: What are the two types of neurons?
• Sensory neurons– What do sensory neurons do?• Cells that monitor stimuli and send signals to the spinal
cord or brain.
• Motor neurons– What do motor neurons do?• Cells that carry impulses from the brain or spinal cord
to muscles, glands, or other neurons
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Let’s take a closer look at a neuron.• Dendrites-branchlike structures on the cell body that receive the signal• Cell body-Central part of the neuron that contains the cell nucleus• Axon-rod-like extension off of cell body which conducts signal through
neuron• On your diagram, label dendrite, cell body, cell nucleus, and axon.
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A Neuron
Glial cell
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How are neurons organized?
• Each neuron connects to 100’s of thousands of other neurons.
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How is a signal sent?
• First, a stimulus happens. A stimulus is any incoming information that causes a response.
• The signal moves from the • stimulus dendrites cell body axon another
neuron. • Sensory neurons detect the stimulus, and begin
to send an electrical signal that passes through several neurons.
• The signal then starts all over in another neuron.
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Is it that easy?
• No.• When the signal
gets to the end of a neuron, it comes to a synapse, or a small space between the neurons.
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What happens at the synapse?In order to transmit the signal from one neuron to another across the synapse, the neuron releases a chemical called a neurotransmitter.
Neurotransmitters act as chemical messengers from one neuron to another.
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Neurotransmitters and Disease
• Dopamine is a neurotransmitter related to muscular function
• Serotonin is a neurotransmitter that is associated with “happy” nerve signals
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Once a signal is sent through the neurons, where does it go?
• It is usually sent to the brain, processed, and then another signal is sent through the motor neurons to induce movement or give a response.
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• Think about when you touch a hot object.• You withdraw your hand without having to
think at all.• Your brain processes it later.• This quick response to a stimulus that does
not require a trip to the brain is called a reflex arc.
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The brain is not involved in a reflex arc.
Look at the picture describe where the signal is sent and how it is returned.
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Ms. Plecki’s Biology Class Proudly Presents….
A BIODRAMA ONTHE NERVOUS SYSTEM
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Study your notes for 3 minutes.
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Motor Neurons
• Left hand= dendrite• Body= cell body• Right hand= axon
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• http://teachhealthk-12.uthscsa.edu/curriculum/brain/pa03pdf/0301E-Wires.pdf