Biological Basis of Behavior
Chapter 2
What are the different ways for
doctors to see inside your body?
• CAT (CT Scan)
– noninvasive medical test that
helps physicians diagnose and
treat medical conditions
– scans of internal organs, bones,
soft tissue and blood vessels
– one of the best and fastest tools
for studying the chest, abdomen
and pelvis
PET- Positron Emission Tomography
Scan
• nuclear medicine imaging
• uses small amounts of radioactive material to
diagnose or treat a variety of diseases,
including many types of cancers, heart disease
and certain other abnormalities within the
body
• scan measures important body functions
MRI- Magnetic Resonance Imaging
• uses a powerful
magnetic field, radio
frequency pulses and a
computer to produce
detailed pictures of
organs, soft tissues,
bone and virtually all
other internal body
structures.
Functional MR Imaging (F-MRI)
• imaging uses a powerful magnetic field, radio
frequency pulses and a computer to produce
detailed pictures of organs, soft tissues, bone
and virtually all other internal body structures
• examine the anatomy of the brain
EEG- Electroencephalogram
• test used to detect
abnormalities
related to electrical
activity of the brain
• most common
reason an EEG is
performed is to
diagnose and
monitor seizure
disorders
Transcranial Doppler
• test that
measures the
velocity of blood
flow through the
brain's blood
vessels
Ultrasound
• Involves exposing part of
the body to highfrequency sound waves to
produce pictures of the
inside of the body
• Ultrasound is used to help
physicians evaluate
symptoms such as:
• pain
• swelling
• infection
How does our body work?
You’ve Got a Lot of Nerve!!
• The brain can not work without your
Nervous System.
• The nervous system acts as a
choreographer; it constantly sends and
receives messages that coordinate the
stage show of human behavior.
Neuron Structure
Synapse
Synapse
It all begins with the Neuron
An individual nerve cell
Pg. 59
These neurons send information throughout our whole body
Three types of neurons
–Sensory (sometimes called Afferent)
–Motor (sometimes called Efferent)
–Inter (interneuron)
Sensory Neurons
(Afferent Neurons)
• Take information from the
senses to the brain.
Activity
Motor Neurons
(Efferent Neurons)
• Take information from brain
to the rest of the body.
Activity
Inter Neurons
• Takes messages from
Sensory Neurons to other
parts of the brain or to
Motor Neurons.
Think of it this way…
• You are sitting in math class and that
really annoying guy sneezes on the
back of your head.
• Sensory nerves send the feeling of sticky
wetness up your spinal cord to your brain.
• Sensory nerves pass the information off
to interneurons.
• Interneurons then tell the motor nerves
the plan.
• Motor nerves then travel down your
body and help your hand reach
around and smack the guy upside
the head.
So how does a neuron work??
I’m Glad you
Asked!!!
How Does A Neuron Work?
How does it send a message in our body??
When a neuron is
hanging out doing
nothing, it is called
Resting Potential
When it decides to go to
work and send a message
it is called Action Potential
(the process by which a
neuron fires)
Pg. 60
Steps of Action Potential
Dendrites receive a chemical message from
another neuron across the synapse.
Pieces of this chemical message stick to the
dendrite and these pieces keep adding up.
When the dendrite has taken
as much of the chemical that
it can hold the soma reaches
its threshold and must fire
This is called the all-or-none response.
The All-or None Response
• The idea that either
the soma (cell body)
fires or it doesn’t
– no part way firing
– And it is same strength
each time…no stronger
or weaker signals
– And it is the same
direction each time
Steps of Action Potential – cont.
• The message then travels down the
axon in the next neuron where it is
stored waiting to reach its next
threshold
• Terminal buttons turn these messages into
chemicals (neurotransmitter) and shoots the
message to next neuron across the synapse.
• The process is repeated again
and again until the message
reaches where it needs to go
• Sometimes there is too much chemical that is
sent across the synapse and it is involved in a
process called Reuptake
– Chemical that is extra goes back to the neuron
that sent it out
• Natures version of recycling
– If Reuptake doesn’t happen, there could be some
type of bodily problem
Pg
61
Refractory Period
• The amount of time
it takes for an
excitable membrane
to be ready for a
second stimulus
once it returns to its
resting state
following excitation
Field Trip
Reflexes
• Normally, sensory
(afferent) neurons
take info up through
spine to the brain.
• Some reactions occur
when sensory neurons
reach just the spinal
cord.
• Survival adaptation.
Neurotransmitters
• Natural chemical
messengers released by
terminal buttons
• Different ones do
different things to your
body.
• Each neurotransmitter
has a specific shape
that fits into a specific
shape of a dendrite
Acetylcholine (ACH)
• Its function is memory, mood and motor
movement
To much and you will…
shake
Not enough and you will experience…
paralysis
Lack of ACH has been linked to Alzheimer’s disease.
Dopamine
• Its function is motor movement and feelings
of excitement
Lack of dopamine is associated with
Parkinson’s disease.
•People can’t make smooth
movements
Overabundance is
associated with
schizophrenia.
Serotonin
• Deals with mood control.
Lack of serotonin
has been linked
to depression.
Too much..
headaches
Norepinephrine
• Plays a role in attention and focus
• Plays a part in flight or fight
To much… fear and
anxiety
Not enough…
depression
Endorphins
• Its function is with pain
control.
– The body’s natural pain killer
– “runners high”
We become addicted to
endorphin causing feelings.
GABA
• A major inhibitory
neurotransmitter: controls
neural excitement throughout
the nervous system
• Regulates muscles tone
• Used to treat ADHD
• Undersupply linked to
seizures, tremors and
insomnia
Glutamate
• Major excitatory neurotransmitter; involved in
memory and learning
• Oversupply = overstimulated brain causing
migraines or seizures
• This is why people avoid MSG in foods!
Now, although we have all of these
neurotransmitters naturally in our
bodies, modern medicine has
figured out a way to manipulate
them using what we call
Agonists and Antagonists
Agonists
 Chemicals that mimic the action
of a particular neurotransmitter
 Nicotine, morphine, and caffeine
are examples
 A copy of the “key”
Antagonists
 Chemicals that block the action of
a particular neurotransmitter.
 Because they occupy the receptor
site, they prevent other
neurotransmitters from acting.
 Some drugs can block the
neurotransmitter responsible for
movement thus paralyzing an individual