Transcript Neurotransmitter proteins

The Nervous System
Nervous System
• Network of connected
cells, tissue, and organs
• Controls thoughts,
movement, life
processes
• Quick responses
– Ex: Sunny day  pupils
shrinking
CNS and PNS
Neurons
• AKA: Nerve Cells
• Transfer electrical impulses to/from the brain
• 3 Main Parts
1) Cell body: contains nucleus and organelles
2) Dendrites: branches that receive messages from neighboring
cells
3) Axon: extension that carries messages away from the cell body
Three Types of Neurons:
1) Sensory
– Detect stimuli and
transmit signals to/from
the brain
– Detect sense (sight, smell,
sound, taste, touch)
Three Types of Neurons:
2) Interneuron
– Located in the brain
– Receive signals from the sensory neurons
Three Types of Neurons:
3) Motor
– Pass messages to other tissue
– Ex: Nerve attached to muscle
• Muscle reacts by contracting and stretching
Resting Potential
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Interior
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• Defined: Neuron at rest
• Neuron Interior is negative
due to abundance of
• Neuron Exterior is positive in
proteins, but…
charge due to abundance of
Na+ outside
– Some K+ inside the cell
Action Potential
• Defined: Electrical impulse
is triggered & moves quickly
down axon
• Generating the Impulse
– Na channels open and
allow Na+ to enter the
cell
– Area becomes positively
charged (impulse)
• After the Impulse
– K channels open to allow
K+ to exit the cell
– Area returns to negative
charge
• Process continues down the
axon
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Cleaning Up
the Mess
• Who?
– Na/K pump
• What?
– Na is pumped back out of
the cell…
– K is pumped back into the
cell
• When?
– After the impulse has
passed
• Where?
– Located in cell membrane
• Why?
– To restore the initial
charge inside & outside
the cell
• How?
– Active transport (use of
ATP)
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Synapse
• Defined: Gap between
neurons
• Problem: Impulse cannot
cross the gap
• Solution: Neurotransmitter
proteins sent from one cell to
another
• Steps:
1) Impulse reaches axon
terminal (end)
2) Vesicle releases
neurotransmitters, which
attach to receptors on
neighbor
3) Na channels open on
dendrite of neighboring
cell…new impulse created
Na
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Vesicle exits the
cell and dissolves
imp
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Impulse reaches the
axon terminal
Terminal end
of one cell
Dendrite of
another cell
Neurotransmitters
diffuse across the
synapse and attach to
receptors of a
neighboring neuron
impul
se
Neurotransmitters
cause Na
channels to
open… creating
new impulse
Na
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Terminal end
of one cell
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Dendrite of
another cell
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Brain
impulse
neurotransmitters
impulse
neurotransmitters
impulse
neurotransmitters
impulse
neurotransmitters
impulse
Feet
Impulses eventually reach the muscles…
and causes MOVEMENT!
Kobe Kuiz
1) What is the function of the nervous system?
2) List the 3 main parts and describe the purpose of the 3
main parts of a neuron.
3) Describe the internal and external environment of a
neuron in resting potential.
4) What is a synapse and why is it a problem for neurons?
5) What are the roles of the following during an action
potential?
1) NA+
2) K+
3) Neurotransmitters