Chapter Four: Neurons, Hormones, and the Brain
Chapter Four Glossary
INTRODUCTION
This interactive glossary contains definitions to the key terms in each chapter.
The "text" link will take you to the section of the interactive chapter
guide that explores that concept.
activation-synthesis
theory
The theory that dreaming results from the cortical synthesis and interpretation of
neural signals triggered by activity in the lower part of the brain .text
adrenal
hormones
Hormones produced by the adrenal glands that are involved in emotion and stress;
they include cortical, epinephrine, and norepinephrine. text
amygdala
A brain structure involved in the arousal and regulation of emotion; it may also
play a role in the association of memories formed in different senses. text
autonomic
nervous system
The subdivision of the peripheral nervous system that regulates the internal organs
and glands. text
axon
A neuron's extending fiber that conducts impulses away from the cell body and transmits
them to other neurons. text
brain
stem
The part of the brain at the top of the spinal cord; it is responsible for automatic
functions such as heartbeat and respiration. text
cell
body
The part of the neuron that keeps it alive and determines whether it will fire. text
central
nervous system (CNS)
The portion of the nervous system consisting of the brain and spinal cord. text
cerebellum
A brain structure that regulates movement and balance, and that is involved in the
learning of certain kinds of simple responses. text
cerebral
cortex
A collection of several thin layers of cells covering the cerebrum; it is largely
responsible for higher mental functions. Cortex is Latin for "bark" or
"rind." text
cerebral
hemisphere
The two halves of the cerebrum. text
cerebrum
The largest brain structure, consisting of the upper part of the forebrain; it is
in charge of most sensory, motor, and cognitive processes. From the Latin for "brain."
text
corpus
callosum
The bundle of nerve fibers connecting the two cerebral hemispheres. text
(in split
brain discussion)
dendrites
A neuron's branches that receive information from other neurons and transmit it toward
the cell body. text
electroencephalogram
(EEG)
A recording of neural activity detected by electrodes. text
endocrine
glands
Internal organs that produce hormones and release them into the bloodstream. text
endorphins
Chemical substances in the nervous system that are similar in structure and action
to opiates; they are involved in pain reduction, pleasure, and memory, and are known
technically as endogenous opioid peptides. text
evoked potentials
Patterns of brain activity produced in response to specific events.
glial
cells
Cells that hold neurons in place, insulate neurons, and provide neurons with nutrients.
text
hippocampus
A brain structure involved in the storage of new information in memory. text
hormones
Chemical substances, secreted by organs called glands, that affect the functioning
of other organs. text
hypothalamus
A brain structure involved in emotions and drives vital to survival, such as fear,
hunger, thirst, and reproduction; it regulates the autonomic nervous system. text
lateralization
Specialization of the two cerebral hemispheres for particular psychological operations.
text
limbic
system
A group of brain areas involved in emotional reactions and motivated behavior. text
localization
of function
Specialization of particular brain areas for particular functions. text
medulla
A structure in the brainstem responsible for certain automatic functions, such as
breathing and heart rate. text
melatonin
A hormone secreted by the pineal gland that is involved in the regulation of daily
biological rhythms. text
MRI (magnetic
resonance imaging)
A method for studying body and brain tissue, using magnetic fields and special radio
receivers. text
myelin
sheath
A fatty insulation that may surround the axon of a neuron. text
nerve
A bundle of nerve fibers (axons and sometimes dendrites) in the peripheral nervous
system. text
neuromodulators
Chemical messengers in the nervous system that increase or decrease the action of
specific neurotransmitters. text
neuron
A cell that conducts electrochemical signals; the basic unit of the nervous system.
Also called a nerve cell. text
neuropsychology
The field of psychology concerned with the neural and biochemical bases of behavior
and mental processes.
neurotransmitter
A chemical substance that is released by a transmitting neuron at the synapse and
that alters the activity of a receiving neuron. text
parasympathetic
nervous system
The subdivision of the autonomic nervous system that operates during relaxed states
and that conserves energy. text
peripheral
nervous system
All portions of the nervous system outside the brain and spinal cord; it includes
sensory and motor nerves. text
PET
scan (positron emission tomography)
A method for analyzing biochemical activity in the brain, using injections of a glucose
like substance containing a radioactive element. text
pituitary
gland
A small endocrine gland at the base of the brain that releases many hormones and
regulates other endocrine glands. text
pons
A structure in the brain stem involved in, among other things, sleeping, waking,
and dreaming. text
reflex
An automatic response to a stimulus.
rapid
eye movement (REM) sleep
Sleep periods characterized by eye movement, loss of muscle tone and dreaming. text
reticular
activating system (RAS)
A dense network of neurons found in the core of the brain stem; it arouses the cortex
and screens incoming information. text
sex
hormones
Hormones that regulate the development and functioning of reproductive and sex organs
and that stimulate the development of male and female sexual characteristics; they
include androgens (such as testosterone), estrogens, and progesterone. text
somatic
nervous system
The subdivision of the peripheral nervous system that connects to sensory receptors
and to skeletal muscles; sometimes called the skeletal nervous system. text
spinal
cord
A collection of neurons and supportive tissue running from the base of the brain
down the center of the back, protected by a column of bones (the spinal column).
text
sympathetic
nervous system
The subdivision of the autonomic nervous system that mobilizes bodily resources and
increases the output of energy during emotion and stress. text
synapse
The site where transmission of a nerve impulse from one nerve cell to another occurs;
it includes the axon terminal, the synaptic cleft, and receptor sites in the membrane
of the receiving cell. text
thalamus
A brain structure that relays sensory messages to the cerebral cortex. text
