Download Neurons

Biological Psychology
 branch of psychology concerned with the links
between biology and behavior
 some biological psychologists call themselves
behavioral neuroscientists, neuropsychologists,
behavior geneticists, physiological psychologists, or
biopsychologists
Neural Communication
We are biopsychosocial systems.
Cellular Level
(Interconnected
Neurons)
Ethnic Level
(Culture)
Organ Level
(Brain)
Group Level
(Family)
System Level
(Information
Processing)
Individual Level
(Human Being)
Community Level
(Society)
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It all Starts with the Neuron
Neurons: The Messengers
• About 100 billion neurons (nerve cells) in the human
brain
• Neurons have many of the same features as other
cells
– Nucleus
– Cytoplasm
– Cell membrane
• What makes neurons unique is their shape and
function
Neuron Structure
Types of Neurons
Sensory Neurons
(Afferent Neurons)
• Take information from the
senses to the brain.
Motor Neurons
(Efferent Neurons)
• Take information from brain
to the rest of the body.
Inter Neurons
• Take messages
from Sensory
Neurons to
Motor
Neurons.
• Found mostly
in spinal cord
Glial Cells
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Cells that insulate and support neurons
Create the myelin sheath
Remove waste products
Provide nourishment
Prevent harmful substances from entering the
brain
The Neural Impulse
• Resting Potential
– Neuron is not transmitting information – it is resting
The All-or None Response
• The idea that
either the
neuron fires or
it does not- no
part way firing.
• Like a gun
How a Neuron Fires
It is an electrochemical process
• Electrical inside the neuron
• Chemical outside the neuron (in
the synapse in the form of a
neurotransmitter).
• The firing is call Action
Potential.
Neural Communication
 Resting Potential
 Nothing is happening. The gates are closed and the positive
ions are on the outside with the negative ions on the inside
of the cell.
– “Negative Ions inside the Neuron is Natural”
 Action Potential – (Neural Impulse)
 a neural impulse; a brief electrical charge that travels down
an axon
 400 ft./sec
Steps of Action Potential
• Dendrites receive neurotransmitter from another
neuron across the synapse.
• Reached its threshold- then fires based on the
all-or-none response.
• Opens up a portal in axon, and lets in positive ions
(Sodium) which mix with negative ions (Potassium)
that is already inside the axon (thus Neurons at
rest have a slightly negative charge).
• The mixing of + and – ions causes an electrical
charge that opens up the next portal (letting in
more K) while closing the original portal.
• Process continues down axon to the axon
terminal.
• Terminal buttons turns electrical charge into
chemical (neurotransmitter) and shoots message
to next neuron across the synapse.
Neural Communication
Stimulation causes the gates to open and the positive
ions enter the cell. An electrical spark is produced by the process
call depolarization. The positive ions are then pumped out.
Cell body end
of axon
This chain reaction
can occur up to 100 a second.
Direction of neural impulse: toward axon terminals
The Neural Impulse
• Polarization
– When the inside of the Neuron is negatively
charged relative to the outside (resting potential)
• Depolarization
– When the electrical charge of a cell moves toward
zero (action potential)
The Synapse
• Synaptic space (synaptic cleft)
– Tiny gap between neurons
• Terminal button
– Enlarged area at the end of an axon
• The synapse
– Composed of the terminal button of one neuron, the
synaptic space, and the dendrites or cell body of the
receiving neuron
Neural Communication
How Neurons Communicate
Neural Communication
• Refractory Period
– The time it takes for the positive ions to be
pumped out.