Term Definition
Psychological science The study, through research, of mind, brain, and behavior.
Gene expression Whether a particular gene is turned on or off.
Chromosomes Structures within the cell body that are made up of DNA, segments of
which comprise individual genes.
Genes The units of heredity that help determine an organism’s
characteristics.
Dominant gene A gene that is expressed in the offspring whenever it is present.
Recessive gene A gene that is expressed only when it is matched with a similar gene
from the other parent.
Genotype The genetic constitution of an organism, determined at the moment
of conception.
Phenotype Observable physical characteristics, which result from both genetic
and environmental influences.
Heredity Transmission of characteristics from parents to offspring through
genes.
Heritability A statistical estimate of the extent to which variations in a trait within
a population is due to genetics.
Central nervous system The brain and the spinal cord.
(CNS)
Peripheral nervous system All nerve cells in the body that are not part of the central nervous
(PNS) system. The peripheral nervous system includes the somatic and
autonomic nervous systems.
Neurons The basic units of the nervous system; cells that receive, integrate,
and transmit information. They operate through electrical impulses,
communicate with other neurons through chemical signals and form
neural networks.
Dendrites Branchlike extensions of the neuron that detect information form
other neurons.
Cell body The site in the neuron where information from thousands of other
neurons is collected and integrated.
Axon A long, narrow outgrowth of a neuron by which information is
conducted from the cell body to the terminal buttons.
Terminal buttons At the ends of axons, small nodules that release chemical signals from
the neuron into the synapse.
1
, Synapse The gap between the terminal buttons of a “sending” neuron and the
dendrites of a “receiving” neuron, where chemical communication
occurs between the neurons.
Action potential The electrical signal that passes along the axon and subsequently
causes the release of chemicals from the terminal buttons.
Resting membrane The electrical charge of a neuron when it is not active.
potential
Relative refractory period The brief period of time following action potential when a neuron’s
membrane potential is more negative, or hyperpolarized, making it
harder to fire again.
All-or-none principle The principle that when a neuron fires, it fires with the same potency
each time; a neuron either fires or not, although the frequency of
firing can vary.
Absolute refractory period The brief period of time following an action potential when the ion
channel is unable to respond again.
Myelin sheath A fatty material, made up of glial cells, that insulates some axons to
allow for faster movement of electrical impulses along the axon.
Nodes of Ranvier Small gaps of exposed axon between the segments of myelin sheath,
where action potentials take place.
Neurotransmitters Chemical substances that transmit signals from one neuron to
another.
Receptors In neurons, specialized protein molecules on the postsynaptic
membrane; neurotransmitters bind to these molecules after passing
across the synapse.
Reuptake The process whereby a neurotransmitter is taken back into the
presynaptic terminal buttons, thereby stopping its activity.
Broca’s area A small portion of the left frontal region of the brain, crucial for the
production of language.
Electroencephalography A technique for measuring electrical activity in the brain.
(EEG)
Positron emission A method of brain imaging that assesses metabolic activity by using a
tomography (PET) radioactive substance injected into the bloodstream.
Magnetic resonance A method of brain imaging that uses a powerful magnetic field to
imaging (MRI) produce high-quality images of the brain.
Functional magnetic An imaging technique used to examine changes in the activity of the
resonance imaging (fMRI) working human brain by measuring changes in the blood’s oxygen
levels.
Transcranial magnetic The use of strong magnets to briefly interrupt normal brain activity as
stimulation (TMS) a way to study brain regions.
2
Psychological science The study, through research, of mind, brain, and behavior.
Gene expression Whether a particular gene is turned on or off.
Chromosomes Structures within the cell body that are made up of DNA, segments of
which comprise individual genes.
Genes The units of heredity that help determine an organism’s
characteristics.
Dominant gene A gene that is expressed in the offspring whenever it is present.
Recessive gene A gene that is expressed only when it is matched with a similar gene
from the other parent.
Genotype The genetic constitution of an organism, determined at the moment
of conception.
Phenotype Observable physical characteristics, which result from both genetic
and environmental influences.
Heredity Transmission of characteristics from parents to offspring through
genes.
Heritability A statistical estimate of the extent to which variations in a trait within
a population is due to genetics.
Central nervous system The brain and the spinal cord.
(CNS)
Peripheral nervous system All nerve cells in the body that are not part of the central nervous
(PNS) system. The peripheral nervous system includes the somatic and
autonomic nervous systems.
Neurons The basic units of the nervous system; cells that receive, integrate,
and transmit information. They operate through electrical impulses,
communicate with other neurons through chemical signals and form
neural networks.
Dendrites Branchlike extensions of the neuron that detect information form
other neurons.
Cell body The site in the neuron where information from thousands of other
neurons is collected and integrated.
Axon A long, narrow outgrowth of a neuron by which information is
conducted from the cell body to the terminal buttons.
Terminal buttons At the ends of axons, small nodules that release chemical signals from
the neuron into the synapse.
1
, Synapse The gap between the terminal buttons of a “sending” neuron and the
dendrites of a “receiving” neuron, where chemical communication
occurs between the neurons.
Action potential The electrical signal that passes along the axon and subsequently
causes the release of chemicals from the terminal buttons.
Resting membrane The electrical charge of a neuron when it is not active.
potential
Relative refractory period The brief period of time following action potential when a neuron’s
membrane potential is more negative, or hyperpolarized, making it
harder to fire again.
All-or-none principle The principle that when a neuron fires, it fires with the same potency
each time; a neuron either fires or not, although the frequency of
firing can vary.
Absolute refractory period The brief period of time following an action potential when the ion
channel is unable to respond again.
Myelin sheath A fatty material, made up of glial cells, that insulates some axons to
allow for faster movement of electrical impulses along the axon.
Nodes of Ranvier Small gaps of exposed axon between the segments of myelin sheath,
where action potentials take place.
Neurotransmitters Chemical substances that transmit signals from one neuron to
another.
Receptors In neurons, specialized protein molecules on the postsynaptic
membrane; neurotransmitters bind to these molecules after passing
across the synapse.
Reuptake The process whereby a neurotransmitter is taken back into the
presynaptic terminal buttons, thereby stopping its activity.
Broca’s area A small portion of the left frontal region of the brain, crucial for the
production of language.
Electroencephalography A technique for measuring electrical activity in the brain.
(EEG)
Positron emission A method of brain imaging that assesses metabolic activity by using a
tomography (PET) radioactive substance injected into the bloodstream.
Magnetic resonance A method of brain imaging that uses a powerful magnetic field to
imaging (MRI) produce high-quality images of the brain.
Functional magnetic An imaging technique used to examine changes in the activity of the
resonance imaging (fMRI) working human brain by measuring changes in the blood’s oxygen
levels.
Transcranial magnetic The use of strong magnets to briefly interrupt normal brain activity as
stimulation (TMS) a way to study brain regions.
2
