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Unit 3 – Biological Bases of
Behavior (Neuroscience)
• We can’t have the mind without the body!
• Without your genes, your brain, your
appearance - you would be nobody.
• Our understanding of how the brain gives
birth to the mind has come a long way.
– Ancient Greek philosophers 
Enlightenment/Scientific Revolution
– Phrenology
Just as I
Thought,
low self
esteem
Why can’t
my skull
bumps
be prettier?
Phrenology
Franz Gall-(1758-1828)
Why so popular?
•Individual ability to change and develop
Pseudoscience-based on false
assumptions.
•Improved treatment of the insane (organic)
•Encouraged people to think scientifically
Modern Science
We are a collection of systems:
Cells form organs
Organs form body systems (digestion,
circulation, etc.)
Body systems make up the individual
Individuals are parts of families, cultures
and communities
We are biopsychosocial systems!
We are going to start small and
go big
Module 7: Neural and Hormonal Systems
Neurons:
The Building Blocks
of the Nervous
System
What are the primary parts
of a typical neuron?
•
•
•
•
Nervous system • Axon
Neurons
• Terminal
branches of Axon
Dendrites
•
Myelin
Sheath
Soma
Nervous System
• The electrochemical communication
system of the body
• Sends messages from the brain to
the body for movement
• Brings information to the brain from
the senses
Neuron
• The basic building block of the
nervous system -- a nerve cell
• Neurons perform three basic tasks
–Receive information
–Carry the information
–Pass the information on to the next
neuron
Neurons
• Neurons “fire” -- send an impulse down
their length -- or they don’t “fire”
• Neurons come in a variety of shapes,
sizes, etc.
Parts of the Neuron
Parts of the Neuron - Dendrites
Parts of the Neuron - Soma
Parts of the Neuron - Axon
Parts of the Neuron – Myelin Sheath
Parts of the Neuron - Terminals
Neuron
Neuron
Candy Neuron Activity
• Sign up for what to bring
Neural
Communication:
The Neural Impulse
Action Potential
• A brief electrical charge that
travels down the axon of the
neuron.
• A neural impulse
• Considered an “on” condition of
the neuron
Refractory Period
• The “recharging phase” when a
neuron, after firing, cannot
generate another action potential
• Once the refractory period is
complete the neuron can fire again
Resting Potential
• The state of a neuron when it is at
rest and capable of generating an
action potential
• The neuron is set and ready to fire
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.
Neuron firing like a Toilet
1. Like a Neuron, a toilet has an action
potential. When you flush, an
“impulse” is sent down the sewer
pipe
Neuron firing like a Toilet
2. Like a neuron, a toilet has a
refractory period. There is a short
delay after flushing when the toilet
cannot be flushed again because the
tank is being refilled
Neuron firing like a Toilet
3. Like a Neuron, a toilet has a resting
potential. The toilet is “charged”
when there is water in the tank and it
is capable of being flushed again
4. Like a Neuron, a toilet operates on
the all-or-none principle – it always
flushes with the same intensity, no
matter how much force you apply to
the handle
All-or-None Principle
• The principle that if a neuron fires it will
always fire at the same intensity
• All action potentials are of the same
strength.
• A neuron does NOT fire at 30%, 45% or
90% but at 100% each time it fires.
Module 7: Neural and Hormonal Systems
Communication
Between Neurons
Synapse
• The tiny, fluid filled gap between the
axon terminal of one neuron and the
dendrite of another neuron
• The action potential cannot jump the
gap
Neurotransmitters
• A chemical messenger that travels
across the synapse from one neuron to
the next
• Can influence whether the second
neuron will generate an action potential
or not
Neurotransmitters
Common Neurotransmitters & Functions
Neurotransmitter
Function
Examples of
Malfunctions
Acetylcholine (ACh)
Muscle action, learning,
memory
Deterioration assoc with
Alzheimer’s disease
Dopamine
Movement, learning,
emotion, attention
Excess receptors assoc
with Schizophrenia; Lack
produces Pakinson’s
disease
Serotonin
Mood, hunger, sleep,
arousal
Undersupply linked to
depression; Prozac used
to raise levels
Norepinephrine
Controls alertness &
arousal
Undersupply can
depress mood
GABA (gamma
aminobutyric acid)
Major inhibitory NT
Undersupply linked to
seizures, tremors,
insomnia
Glutamate
Major excitatory NT
Oversupply produces
migraines/seizures.
Excitatory Effect
• A neurotransmitter effect that makes it
more likely that the receiving neuron
will generate an action potential
(impulse)
• The second neuron is more likely to fire.
Inhibitory Effect
• A neurotransmitter effect that makes it
less likely that the receiving neuron will
generate an action potential (impulse)
• The second neuron is less likely to fire.
Threshold
• The level of stimulation required to trigger
a neural impulse.
How drugs alter neurotransmitters
• Affected at the synapses by either
blocking or amplifying NT activity.
• AGONIST- amplify normal sensations of
arousal or pleasure
• ANTAGONIST- block NT functioning; can
cause paralysis
How Neuron’s work video
https://www.youtube.com/watch?v=FR4S1B
qdFG4&feature=related
Neuron Dance!
https://www.youtube.com/watch?v=mcQ1H4
K64kA
Module 7: Neural and Hormonal Systems
Neural
Communication:
The Neural Chain
Receptor Cells
• Specialized cells in the sensory systems
of the body that can turn other kinds of
energy into action potentials that the
nervous system can process
• Receptor cells in the eye turn light into a
neural impulse the brain understands.
Sensory Nerves (aka AFFERANT)
• Nerves that carry information to the
central nervous system
• Connect the sense organs to the brain
and spinal cord
Interneurons
• Nerve cells in the brain and spinal cord
responsible for processing information
related to sensory input and motor
output
Motor Nerves (aka EFFERANT)
• Nerves that carry information from the
central nervous system
• Carries messages from the brain and
spinal cord to other parts of your body
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain
Module 7: Neural and Hormonal Systems
The Structure of the
Nervous System
The Nervous System
Central Nervous System (CNS)
• The brain and spinal cord
• The brain is the location of most
information processing.
• The spinal cord is the main pathway to
and from the brain.
Spinal Cord
Divisions of the Nervous System
Peripheral Nervous System (PNS)
• The sensory and motor nerves that
connect the central nervous system to
the rest of the body
• Peripheral means “outer region”
• The system is subdivided into the
somatic and autonomic nervous
systems.
Divisions of the Nervous System
Somatic Nervous System
• The division of the peripheral nervous
system that controls the body’s skeletal
muscles
• Contains the motor nerves needed for
the voluntary muscles
Divisions of the Nervous System
Autonomic Nervous System
• The division of the peripheral nervous
system that controls the glands and
muscles of the internal organs
• Monitors the autonomic functions
• Controls breathing, blood pressure, and
digestive processes
• Divided into the sympathetic and
parasympathetic nervous systems
Divisions of the Nervous System
Sympathetic Nervous System
• The part of the autonomic nervous
system that arouses the body to deal
with perceived threats
• Fight or flight response
Divisions of the Nervous System
Parasympathetic Nervous System
• The part of the autonomic nervous
system that calms the body
• Brings the body back down to a relaxed
state
Divisions of the Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Sympathetic and Parasympathetic Divisions of the
Autonomic Nervous System
The Nervous System and the Endocrine System
The Endocrine
System
Endocrine System
• One of the body’s two communication
systems.
• A set of glands that produce hormones-chemical messengers that circulate in the
blood
Hormone
• Chemical messengers produced by the
endocrine glands and circulated in the
blood
• Similar to neurotransmitters in that they
are also messengers
• Slower communication system, but with
longer lasting effects
Pituitary Gland
• The endocrine system’s gland that, in
conjunction with the brain, controls the
other endocrine glands
• Called the “master gland”
• Located at the base of the brain and
connects to the hypothalamus
Endocrine System – Pituitary Gland
Thyroid Gland
• Endocrine gland that helps regulate the
energy level in the body
• Located in the neck
Endocrine System – Thyroid Gland
Adrenal Gland
• Endocrine glands that help to arouse the
body in times of stress
• Located just above the kidneys
• Release epinephrine (adrenaline) and
norepinephrine (noradrenaline) –
increase heart rate, blood pressure,
blood sugar.
Endocrine System – Adrenal Gland
Pancreatic Gland
• Regulates the level of blood sugar in the
blood
Endocrine System – Pancreatic Gland
Sex Glands
• Ovaries (females) and testes (males) are
the glands that influence emotion and
physical development.
• Testosterone – primary male hormone
• Estrogen – primary female hormone
• Males and females have both estrogen
and testosterone in their systems.
Endocrine System – Sex Glands