The Nervous System Network of connected cells, tissue, and organs Controls thoughts, movement, life...
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The Nervous System
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Transcript of The Nervous System Network of connected cells, tissue, and organs Controls thoughts, movement, life...
The Nervous System
• Network of connected cells, tissue, and organs
• Controls thoughts, movement, life processes
• Quick responses– Ex: Sunny day pupils
shrinking
Nervous System
CNS and PNS
• AKA: Nerve Cells• Transfers electrical impulses to/from the brain• 3 Main Parts1) Cell body: contains nucleus and organelles2) Dendrites: branches that receive messages from neighboring cells3) Axon: extension that carries messages away from the cell body
Neurons
Types of Neurons
• Sensory– Detect stimuli and
transmit signals to/from the brain
– Detect sense (sight, smell, sound, taste, touch)
• Interneuron– Located in the brain– Receive signals from the sensory neurons
Types of Neurons
• Motor– Pass messages to other tissue– Ex: Nerve attached to muscle
• Muscle reacts by contracting and stretching
Types of Neurons
Resting Potential• Defined: Neuron
at rest• Neuron Exterior:
– Positive charge– Mainly Na+
outside the cell• Neuron Interior:
– Negative charge (from various proteins)
– K+ inside the cell
Action Potential• Defined: Electrical impulse
is triggered• Front end of impulse
– Channels open and allow Na+ to enter the cell
– Negative impulse attracted towards positive Na+
• Back end of impulse– Channels open to allow
K+ to exit the cell– Interior returns to
normal• Impulse pulled along by the
changing of electrical charges
impulse
Na+ Na+
Na+Na+
Na+
Na+
Na+Na+
Na+Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+ Na+
Na+Na+
Na+
Na+
Na+Na+
Na+Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
K+
K+
K+
K+
K+
K+
K+
K+
K+
K+
K+
K+
K+
K+
Na+
Na+
Na+
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Na+
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Na+K+
K+
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K+K+
Na+ Na+
Na+Na+
Na+
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Na+ Na+
Na+
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Na+
Na+Na+
Na+
Na+Na+
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Na+ Na+
Na+
Na+
Na+Na+Na+ Na+
Na+
Na+ Na+
Na+
Na+
Na+
Na+
Na+
Na+Na+
Na+
Na+
Na+Na+
Na+Na+
Na+
K+ K+
K+
K+negative impulse
K+K+
K+
K+
K+
K+
K+ K+
K+
Synapse• Defined: Gap between
neurons• Problem: Impulse cannot
cross the gap• Solution: Impulse converted
into chemical molecules (neurotransmitters)
• Steps:– Impulse reaches
neuron’s end– Vesicle releases
neurotransmitters– Neurotransmitters attach
to neighboring neuron– New impulse created
impulse
Impulse stimulates a vesicle, which contains neurotransmitters
Vesicle exits the cell and dissolves
End of one cell
Start of another cell
impulse imp
ulse
Neurotransmitterscross the synapse and attach to receptors of a neighboring neuron
Neurotransmitters stimulate a new impulse
End of one cell
Start of another cell
Feet
Brain
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• Impulse causes the muscles to stretch and contract…this causes MOVEMENT!
Motor neurons reach the muscles…
