Neural and Hormonal Systems
ARE A UNION OF OPPOSITES!
Will Explain Why We FEEL
Nervous
Strong
Pain
Sick
It all Starts with the Neuron
Neuron Structure
Neurons do NOT touch each other- the
space in between is call the synapse.
Neural Structure Metaphorically
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Dendrite is like a tree. Also, each branch is a
telephone wire that carries incoming
messages to you. Dendrites DETECT
All or None is like a gun. Fires completely
or not at all.
Myelin is like the insulation that covers
electrical wires.
Neuron is like a silicon chip in a computer
that receives and transmits information
between input and output devices as well as
between other chips.
Axon is like an electrical cable that carries
information. Axons ANNOUNCE
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(Union of Opposites)
Resting Potential is like a battery. Stable
until electrical charge stimulates it.
Terminal Button is like the nozzle at the end
of a hose, from which water is squirted.
Synapse is like a railroad junction, where two
trains may meet.
How a Neuron Fires
It is an electrochemical process
• Electrical inside the neuron (MS)
• Chemical outside the neuron (in the
synapse in the form of a
neurotransmitter).
• The firing is called Action Potential.
The All-or None Response
• The idea that
either the
neuron fires or
it does not- no
part way firing.
• Like a gun
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 (Union of Opposites)
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.
Action Potential
Neural Impulse Like a Toilet: FLUSH!
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all-or-none principle - the toilet either
flushes completely or not at all; it doesn’t
flush a little or a lot
Like a Toilet Because…
direction of impulse - the toilet only flushes
one way, the impulse can’t come the other
direction (you hope!)
refractory period - after you flush the toilet,
it won’t flush again for a certain period of
time, even if you push the handle repeatedly
threshold - you can push the handle a little
bit, but it won’t flush until you push
the handle past a certain critical point - this
corresponds to the level of excitatory
neurotransmitters that a neuron must absorb
before it will fire
resting potential- if you are using a toilet
with a tank, the water in the tank can
represent resting potential. The toilet is
“waiting” to fire, and the water in the tank
represents the overall negative charge inside
the neuron waiting for depolarization
action potential - the action potential is represented
by opening the flap in the tank and the water draining
(flushing) down into the bowl
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See Neural Impulse Clip
Neurotransmitters “The KEYS” to Transmission
2 Types (Excitatory/Inhibitory)
2 Ways to Change Their Effect
(Agonist and Antagonist)
Union of Opposites
• Chemical messengers released by
terminal buttons through the
synapse.
• We should know at least 4 types
and what they do and how they
“UNLOCK” the Receptor Sites.
How Neurons Communicate
Agonists and Antagonists
Union of Opposites
How Neurons Communicate
Dopamine (Inhibits)
• Its function is motor movement, alertness,
motivation, reward
• (pp. 156 in CP)
Lack of dopamine is associated with
Parkinson’s disease.
Overabundance is associated with
schizophrenia.
How is an alcoholic
like Parkinson’s?
Acetylcholine (Excites!)
• Its function is motor movement and
maybe memory.
To much and you will….
Not enough and you will….
Lack of ACH has been linked to
Alzheimer’s disease.
Serotonin
• Function deals with mood control , sleep,
appetite, control.
• (pp. 156 in CP)
Lack of serotonin has
been linked to
depression.
Prozac=SSRI “Selective
Serotonin Reuptake
Inhibitor”
Endorphins
• Function deals with pain
control.
We become addicted
to endorphin causing
feelings.
Types of Neurons
Sensory Neurons
Motor Neurons
Inter Neurons
Sensory Neurons
(Afferent Neurons)
• Take information from the senses
to the brain.
Inter Neurons
• Take messages
from Sensory
Neurons to other
parts of the brain
or to Motor
Neurons.
Motor Neurons
(Efferent Neurons)
• Take information from brain to the
rest of the body.
Biological Difference: Nucleus
Accumbens
• A region in the frontal cortex that
directs motivation to seek
rewards.
• The nucleus accumbens is
activated by anticipated or
received awards (i.e., monetary,
chocolate). Mouse Party
• “Mind on Drugs!
• A team at the National Institutes
of Mental Health in 2005 saw that
the nucleus accumbens responded
more in adolescents than in
adults when they received a
reward (Monastersky, 2007, para
27).
Biological Difference: Dopamine
• One reason the nucleus
accumbens acts up more in
adolescence is due to the different
ways the younger brains deal with
the neurotransmitter dopamine.
• Dopamine, the brain chemical
involved in motivation and in
reinforcing behavior, is
particularly abundant and active
in the teen years (Wallis, 2004,
para 21)
• In addition to pleasure, novel
situations will cause dopamine to
squirt into the nucleus accumbens.
• Psych Sim: “Mind on Drugs”
• Mouse Party
Divisions of the Nervous System
Sympathetic Nervous System
Flight or Fight Response
A Simple Reflex
A Simplified Neural Network
Neurons that learn to work
together as a team.
The Endocrine System
A system of glands that secrete
hormones.
Similar to nervous system,
except hormones work a lot
slower than neurotransmitters.
Hormones
Neurotransmitters
The Major Endocrine Glands