Transcript Types of neurons

Neurons and Synapses
Types of Neurons
Sensory
Motor
Interneurons
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Sensory Neurons
INPUT From sensory organs to the
brain and spinal cord.
Drawing shows a
somatosensory
neuron
Brain
Sensory
Neuron
Spinal
Cord
Vision, hearing,
taste and smell
nerves are cranial,
not spinal
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Motor Neurons
OUTPUT From the brain and spinal
cord To the muscles and glands.
Sensory
Neuron
Brain
Spinal
Cord
Motor
Neuron
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Interneurons
Interneurons
carry
information
between other
neurons only
found in the
brain and
spinal cord.
Brain
Sensory
Neuron
Spinal
Cord
Motor
Neuron
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Action Potential
Demonstration
 Psych Simulation- 4.0
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Structures of a neuron
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The cell body
Contains the cell’s Nucleus
Round, centrally
located structure
Contains DNA
Controls protein
manufacturing
Directs metabolism
No role in neural
signaling
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Dendrites
 Information
collectors
 Receive inputs
from neighboring
neurons
 Inputs may number
in thousands
 If enough inputs
the cell’s AXON
may generate an
output
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Dendritic Growth
 Mature neurons
generally can’t
divide
 But new dendrites
can grow
 Provides room for
more connections
to other neurons
 New connections
are basis for
learning
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Axon
The cell’s output
structure
One axon per cell,
2 distinct parts
tubelike structure
branches at end
that connect to
dendrites of other
cells
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Myelin sheath
 White fatty casing
on axon
 Acts as an electrical
insulator
 Not present on all
cells
 When present
increases the speed
of neural signals
down the axon.
Myelin Sheath
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Neuron to Neuron
 Axons branch out
and end near
dendrites of
neighboring cells
 A gap separates the
axon terminals from
dendrites
 Gap is the Synapse
Dendrite
Axon
Cell
Body
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Synapse
 axon terminals
contain small
storage sacs
called synaptic
vesicles
Sending
Neuron
Axon
Terminal
Synapse
vesicles contain
neurotransmitter
molecules
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Neurotransmission
 http://camel2.conncoll.edu/academics/zoolog
y/courses/zoo202/Nervous/synapse.html
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Locks and Keys
 Neurotransmitter
molecules have
specific shapes
 Receptor molecules have
binding sites
 When NT binds to
receptor, ions enter
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Some Drugs work on
receptors
 Some drugs are
shaped like
neurotransmitters
 Antagonists : fit the
receptor but poorly
and block the NT
e.g. beta blockers
 Agonists : fit
receptor well and
act like the NT
e.g. nicotine.
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Summary
 3 types of neurons
 The cell membrane
 Ion movements
 Action potentials
 Synapse
 Neurotransmitters
 Receptors and ions
 Agonists and
antagonists
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