AP Psychology Outline
Chapter 3: The Biological Bases of Behavior
Red – Definition
Blue - Important Points
Green - Important People & Contributions
Nervous System: The Basics
1. Neurons – Individual cells in the nervous system that receive, integrate, and transmit information.
a. They are basic links that allow communication within the Nervous System.
b. Soma – Cell Body of the neuron that contains the nucleus and much of cells normal
c. Dendrite – Parts of a Neuron that receives information.
d. Axon – Long fiber that transmits information away to other neurons, muscles, or glands.
e. Myelin Sheath – Insulating Material that encases some Axons.
i. It speeds up to transmission of information.
f. Terminal Button – Small knobs where neurotransmitters are transmitted activating
g. Synapse – Junction where information is transmitted from one neuron to another.
h. There is lots of variety among Neurons, so not all neurons contain all these parts.
2. Glia – Cells in Nervous System that provides various support for neurons.
a. Glial cells supply nourishment to neurons, remove neurons waste products, and provide
insulation around many axons.
The Neural Impulse: Using Energy to Send Information
1. Neural Impulse – The signal that moves through the Neuron.
2. All the Study of the Neuron done on a Squids Neuron (Which is much bigger than a
Humans) By Hodgkin and Huxley.
1. Neuron At Rest
• The Neuron at rest is a small battery, from the uneven Ion charges from the fluid
around it of Sodium (Na) and Potassium (K).
• Resting Potential – The Stable, Negative Charge when the Cell is inactive.
2. The Action Potential
• Action Potential – A very brief shift in a Neuron’s electrical charge that travels
along an axon.
• Absolute Refractory Period – Minimum length of time after an action potential
during which another action potential cannot begin. Only about 1 or 2
• All-Or-None Law – Neural Impulses either Fire or don’t fire. There is no Half-
Fire. A faster Rate of transmission means a stronger Stimulus.
3. The Synapse
• Synaptic Cleft – The gap between the terminal button of one neuron and the cell
membrane of another neuron.
• The two Membranes of the different Neurons do not touch.
• Neurotransmitters – Chemicals that transmit information from one Neuron to
• Synaptic Vesicles – The body that Neurotransmitters are transmitted
across the gap in. • Pre-Synaptic Neuron – The Neuron that sends the Signal across the
• Post-Synaptic Neuron – The Neuron that receives the Signal.
• Receptor Site - Where the Synaptic Vesicles bind releasing the
information into the new Neuron.
4. Receiving Signals: Postsynaptic Potentials
• Post-Synaptic Potential (PSP) – A voltage change at the receptor site on a
postsynaptic cell membrane.
• PSP’s are not All-Or-Nothing Law; they are graded and increase/decrease the
probability of a neural impulse in the receiving Cell.
• Excitatory PSP – Positive Voltage shift, Increases likelihood that
Postsynaptic Neuron will fire Action Potentials.
• Inhibitory PSP – Negative Voltage shift, decreases likelihood that
Postsynaptic Neuron will fire Action Potentials.
• The Voltage shift depends upon which Receptor Sites are activated in
the Postsynaptic Neuron.
• Reuptake – Process which Neurotransmitters are sponged up from the
synaptic cleft by the Presynaptic Membrane.
• Thousands of Neurons are connected to Thousands of Neurons.
• If there is enough Excitatory PSP’s, electrical voltage builds up to the
threshold where an Action Potential can be fired. However, many
Inhibitory PSP’s will cancel the effects of the Excitatory PSP’s.
5. Neurotransmitters and Behavior
• Acetylcholine – Transmitter between Motor Neurons and Voluntary Muscles.
• Agonist – Chemical that mimics the action of a Neurotransmitter.
• Antagonist – Chemical that opposes the action of a Neurotransmitter.
• The Agonist causes PSP’s, while the Antagonist Blocks PSP’s.
• Monoamines – 3 Neurotransmitters: Dopamine, Norepinephrine, and Serotonin.
• Dopamine – Used by Neurons that Control Voluntary Movement.
1. Degeneration of Dopamine leads to Parkinson’s disease.
• Serotonin – Plays a prominent role in sleep, wakefulness, and eating
• Abnormal levels of Monoamines lead to Psychological Disorders.
• Depression = Low activation of Norepinephrine and Serotonin
• Schizophrenia – Over activation of Dopamine Synapses.
1. Schizophrenia affects 1% of Population, and causes
Hospitalization more than any Psychological Disorder.
• Effects of Drugs like Cocaine and Amphetamines are caused by temporary
increased activity at Dopamine and Norepinephrine Synapses.
• GABA – GABA and Glycine acts as inhibitory effects at all synapses.
• Plays in Anxiety, Seizures, and Sleep.
• Endorphins – Internally produced chemicals that resemble Opiates in structure
• Candace Pert & Solomon Snyder: Morphine exerts its effects by
binding to specialized receptors in the Brain. (Endorphin Receptors)
• Endorphins contribute to modulation of Pain and a variety of other
Organization of Nervous System 1. Peripheral Nervous System & Central Nervous System
a. Nerves – Bundles of Neuron Fibers (Axons) that are routed together in the Peripheral
2. Peripheral Nervous System – Made up of all those nerves that lie outside the Brain and Spinal
a. Somatic Nervous System – Made up of Nerves that connect to voluntary skeletal Muscles
and to Sensory Receptors.
i. Afferent Nerve Fibers – Axons that carry inward to Central nervous System
from the Periphery.
ii. Efferent Nerve Fibers – Axons that carry information outward from the Central
Nervous System to the Periphery of the Body.
iii. Somatic Nerves let you “feel” the world and move around in it.
b. Autonomic Nervous System – Made up of Nerves that connect to the heart, blood vessels,
smooth muscles, and glands.
i. Governed by the Central nervous System.
ii. Controls automatic, involuntary, visceral functions.
iii. Also controls physiological effect of Emotions.
1. Flight-Or-Fight Response – Walter Cannon – Organisms respond to
threat Physiologically by preparing for attacking (Fight) or preparing to
iv. Sympathetic Division – Branch of the Autonomic Nervous System that
mobilizes the body’s resources for emergencies. (Fight-or Flight, Adrenaline)
v. Parasympathetic Division – Branch of the Autonomic Nervous system that
generally conserves Bodily Resources. (Digestion, Slowing Heart Rate, etc.)
3. Central Nervous System
a. Central Nervous System – Consists of the brain and the Spinal Cord.
i. Protected by Sheaths called the Meninges.
1. Inflammation of the Meninges is called the Disease Meningitis.