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Chapter 2: The Brain
and Behavior
Divisions of the Nervous System
The Nervous System
Nervous System
Central Nervous
System (CNS)
Peripheral Nervous
System (PNS)
Divisions of the Nervous System
Central Nervous System
Nervous System
Central Nervous
System (CNS)
• Brain and spinal
cord
• Spinal cord
transmits messages
between the brain
and the rest of the
body
Peripheral Nervous
System (PNS)
Divisions of the Nervous System
Peripheral Nervous System
Nervous System
Central Nervous
System (CNS)
Peripheral Nervous
System (PNS)
• Network of long
nerves
• Connects the brain
and spinal cord to
the rest of the
body
Divisions of the Nervous System
Peripheral Nervous System(PNS)
Somatic
division
Somatic division
(voluntary)
Autonomic
division
Autonomic division
(automatic)
Sympathetic
(arousal)
Parasympathetic
(calming)
The Nervous System
 Pathways in the nervous system:
 Afferent nerves (sensory nerves):
carry messages TO the brain and
spinal cord
 Efferent nerves (motor nerves):
carry messages FROM the brain
and spinal cord
 Neural networks: networks of
nerve cells that integrate sensory
and motor nerves
You are listening to a lecture. Then the bell
rings in the hallway. In order to hear this
stimulus, ______ neurons must carry
electrochemical messages from your ears to
your brain.
A.) indigent
B.) afferent
C.) efferent
D.) indifferent
Neurons
 Neurons: nerve cells that process information and
allow communication throughout the body
 Cell body: contains the nucleus
 Directs the manufacturing of nutrients needed for
neural growth and development
Neurons
 Dendrites: receive messages from other neurons
 Axons: carry messages destined for other neurons
Neurons
 Myelin sheath: insulates the axon
 Increases message speed (thicker = faster)
 Terminal buttons: send messages to dendrites of
receiving neuron
Dendrites are ______.
A.) the part of the neuron that is responsible for sending
information away from the cell body toward other cells
B.) the branch-like part of the neuron that is responsible for
receiving information from other neurons
C.) located inside the cell body
D.) the layer of fat cells that encase and insulate the neuron
_____ allows neurons to speed up the
transmission of nerve impulses.
A.) Resting potential
B.) Having more than one cell body
C.) The myelin sheath
D.) Acetylcholine
The Neural Impulse
Resting potential: neuron is
negatively charged at rest
Action potential: positive
electrical charge that sweeps
through the neuron
The Neural Impulse
 All-or–nothing principle: neuron either fires or
does not fire (no difference in strength)
 Must reach a threshold before firing
 Speed varies based
on thickness of
myelin sheath and
length of neuron
Synapses and Neurotransmitters
 Synapse: space between axon
of sending neuron and
dendrites of receiving neuron
 Neurotransmitters: chemicals
that carry messages across the
synapse
 Fit like a lock and key to
receptor sites on the receiving
neuron
Synapses and Neurotransmitters
Synapses and Neurotransmitters
 Reuptake: the re-absorption
of neurotransmitters
 Selective Serotonin Reuptake
Inhibitors (SSRIs)
Brain Structures and Functions
Brain Structures and Functions
Brain Structures and Functions
Brain Structures and Functions
If a person's cerebellum were damaged in an
accident, you would expect the person to have
a problem with _____.
A.) breathing and heart rate
B.) seeing and hearing
C.) talking and understanding
D.) balance and muscle coordination
The most complex mental functions, such as
thinking and planning, take place in the
_____.
A.) corpus callosum
B.) cerebral cortex
C.) cerebellum
D.) amygdala
Brain Structures and Functions
The Brain’s Hemispheres
 Hemispheres: two symmetrical
halves of the brain
 Operates contralaterally
 Lateralization: the dominance of
one hemisphere
 Left: verbal abilities, thinking,
reading, reasoning; sequential
 Right: visual-spatial, music,
emotional expression, drawing;
global
 Communicates via the Corpus
Callosum
Try This
Try This
Genes and Behavior
 Chromosome: threadlike structures that contain
DNA
 23 chromosomes from each parent
 DNA carries all our genetic information (genes)
Genes and Behavior
 Dominant-recessive genes principle: dominant
genes override recessive genes
 Recessive genes appear only if both genes in a pair are
recessive
Genes and Behavior
 Polygenetic inheritance: the influence of
multiple genes on behavior
 Behavior genetics: the study of heredity’s
influence on behavior
 Twin studies
 Adoption studies
Genes and Behavior
 Genotype: a person’s genetic heritage
 Phenotype: the individual’s observable
characteristics
 Are a person’s genotype and phenotype
always the same?
 Why or why not?
Molly’s natural hair color is brown but she has
had it dyed blonde. Molly changed her
_________.
A.) phenotype
B.) genotype
C.) chromosomes
D.) genetic heritage