Chapter 2 Flashcards & Key Terms

acetylcholine
A neurotransmitter produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain.
allocortex
Brain tissue with three layers or unlayered organization.
amygdala
A group of nuclei in the medial anterior part of the temporal lobe.
angiography
A brain-imaging technique in which a specialized X-ray image of the head is taken shortly after the cerebral blood vessels have been filled with a radiopaque dye by means of a catheter.
anterior cerebral arteries
Two large arteries, arising from the carotids, that provide blood to the anterior poles and medial surfaces of the cerebral hemispheres.
apical dendrite
The dendrite that extends from a pyramidal cell to the outermost surface of the cortex.
arachnoid
The thin covering (one of the three meninges) of the brain that lies between the dura mater and pia mater.
arborization
The elaborate branching of the dendrites of some neurons.
astrocyte
A star-shaped glial cell with numerous processes (extensions) that run in all directions.
autonomic ganglia
Collections of nerve cell bodies, belonging to the autonomic division of the peripheral nervous system, that are found in various locations and innervate the major organs.
autonomic nervous system
The part of the peripheral nervous system that supplies neural connections to glands and to smooth muscles of internal organs.
autoradiography
A histological technique that shows the distribution of radioactive chemicals in tissues.
axon collateral
A branch of an axon from a single neuron.
axon hillock
A cone-shaped area from which the axon originates out of the cell body. Functionally, the integration zone of the neuron.
axon terminal
Also called synaptic bouton. The end of an axon or axon collateral, which forms a synapse on a neuron or other target cell.
axon
A single extension from the nerve cell that carries nerve impulses from the cell body to other neurons.
axonal transport
The transportation of materials from the neuronal cell body to distant regions in the dendrites and axons, and from the axon terminals back to the cell body.
basal dendrite
One of several dendrites on a pyramidal cell that extend horizontally from the cell body.
basal ganglia
A group of forebrain nuclei, including caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres.
basilar artery
An artery, formed by the fusion of the vertebral arteries, that supplies blood to the brainstem and to the posterior cerebral arteries.
bipolar neuron
A nerve cell that has a single dendrite at one end and a single axon at the other end.
blood-brain barrier
The mechanisms that make the movement of substances from blood vessels into brain cells more difficult than exchanges in other body organs, thus affording the brain greater protection from exposure to some substances found in the blood.
brainstem
The region of the brain that consists of the midbrain, the pons, and the medulla.
c-fos
An immediate early gene commonly used to identify activated neurons.
carotid arteries
The major arteries that ascend the left and right sides of the neck to the brain, supplying blood to the anterior and middle cerebral arteries.
cauda equina
The caudal-most spinal nerves, which extend beyond the spinal cord proper to exit the spinal column.
caudate nucleus
One of the basal ganglia; it has a long extension or tail.
cell body or soma
The region of a neuron that is defined by the presence of the cell nucleus.
cell nucleus
The spherical central structure of a cell that contains the chromosomes.
central nervous system (CNS)
The portion of the nervous system that includes the brain and the spinal cord.
central sulcus
A fissure that divides the frontal lobe from the parietal lobe.
cerebellum
A structure located at the back of the brain, dorsal to the pons, that is involved in the central regulation of movement.
cerebral cortex
Sometimes called simply cortex. The outer covering of the cerebral hemispheres, which consists largely of nerve cell bodies and their branches.
cerebral hemispheres
The right and left halves of the forebrain.
cerebrospinal fluid (CSF)
The fluid that fills the cerebral ventricles.
cervical
Referring to the topmost 8 segments of the spinal cord, in the neck region.
choroid plexus
A highly vascular portion of the lining of the ventricles that secretes cerebrospinal fluid.
cingulate gyrus
A cortical portion of the limbic system, found in the frontal and parietal midline.
circle of Willis
A structure at the base of the brain that is formed by the joining of the carotid and basilar arteries.
coccygeal
Referring to the lowest spinal vertebra (also known as the tailbone).
computerized axial tomography (CAT or CT)
A noninvasive technique for examining brain structure in humans through computer analysis of X-ray absorption at several positions around the head.
conduction zone
The part of the neuron over which the nerve’s electrical signal may be actively propagated. Usually corresponds to the cell’s axon.
corpus callosum
The main band of axons that connects the two cerebral hemispheres.
cortical column
One of the vertical columns that constitute the basic organization of the neocortex.
cranial nerve
A nerve that is connected directly to the brain.
dendrite
One of the extensions of the cell body that are the receptive surfaces of the neuron.
diencephalon
The posterior part of the forebrain, including the thalamus and hypothalamus.
dorsal root
The branch of a spinal nerve, entering the dorsal horn of the spinal cord, that carries sensory information from the peripheral nervous system to the spinal cord.
dura mater
The outermost of the three meninges that surround the brain and spinal cord.
edema
The swelling of tissue, especially in the brain, in response to injury.
enteric nervous system
An extensive meshlike system of neurons that governs the functioning of the gut.
forebrain
Also called prosencephalon. The frontal division of the neural tube, containing the cerebral hemispheres, the thalamus, and the hypothalamus.
fornix
A fiber tract that extends from the hippocampus to the mammillary body.
fourth ventricle
The passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to surround the brain and spinal cord.
frontal lobe
The most anterior portion of the cerebral cortex.
functional MRI (fMRI)
Magnetic resonance imaging that detects changes in blood flow and therefore identifies regions of the brain that are particularly active during a given task.
glial cells
Also called glia or neuroglia. Nonneuronal brain cells that provide structural, nutritional, and other types of support to the brain.
globus pallidus
One of the basal ganglia.
Golgi stain
A histological stain that fills a small proportion of neurons with a dark, silver-based precipitate.
granule cell
A type of small nerve cell.
gray matter
Areas of the brain that are dominated by cell bodies and are devoid of myelin.
gross neuroanatomy
Anatomical features of the nervous system that are apparent to the naked eye.
gyrus
A ridged or raised portion of a convoluted brain surface.
hindbrain
Also called rhombencephalon. The rear division of the brain, which, in the mature vertebrate, contains the cerebellum, pons, and medulla.
hippocampus
A medial temporal lobe structure that is important for learning and memory.
horseradish peroxidase (HRP)
An enzyme found in horseradish and other plants that is used to determine the cells of origin of a particular set of axons.
hypothalamus
Part of the diencephalon, lying ventral to the thalamus.
immediate early genes (IEGs)
A class of genes that show rapid but transient increases in expression in cells that have become activated.
immunocytochemistry (ICC)
A method for detecting a particular protein in tissues in which an antibody recognizes and binds to the protein and then chemical methods are used to leave a visible reaction product around each antibody.
in situ hybridization
A method for detecting particular RNA transcripts in tissue sections by providing a nucleotide probe that is complementary to, and will therefore hybridize with, the transcript of interest.
inferior colliculi
Paired gray matter structures of the dorsal midbrain that receive auditory information.
innervate
To provide neural input.
input zone
The part of a neuron that receives information, from other neurons or from specialized sensory structures. Usually corresponds to the cell’s dendrites.
integration zone
The part of the neuron that initiates nerve electrical activity, described in detail in Chapter 3. Usually corresponds to the neuron’s axon hillock.
interneuron
A neuron that is neither a sensory neuron nor a motoneuron; it receives input from and sends output to other neurons.
lateral ventricle
A complexly shaped lateral portion of the ventricular system within each hemisphere of the brain.
limbic system
A loosely defined, widespread group of brain nuclei that innervate each other to form a network.
lumbar
Referring to the 5 spinal segments that make up the upper part of the lower back.
magnetic resonance imaging (MRI)
A noninvasive technique that uses magnetic energy to generate images that reveal some structural details in the living brain.
magnetoencephalography (MEG)
A passive and noninvasive functional brain-imaging technique that measures the tiny magnetic fields produced by active neurons, in order to identify regions of the brain that are particularly active during a given task.
mammillary body
One of a pair of nuclei at the base of the brain.
meninges
The three protective sheets of tissue—dura mater, pia mater, and arachnoid—that surround the brain and spinal cord.
meningitis
An acute inflammation of the meninges, usually caused by a viral or bacterial infection.
metencephalon
A subdivision of the hindbrain that includes the cerebellum and the pons.
microglial cells
Also called microglia. Extremely small glial cells that remove cellular debris from injured or dead cells.
midbrain
Also called mesencephalon. The middle division of the brain.
middle cerebral arteries
Two large arteries, arising from the carotids, that provide blood to most of the lateral surfaces of the cerebral hemispheres.
mitochondrion
A cellular organelle that provides metabolic energy for the cell’s processes.
motoneuron
Also called motor neuron. A nerve cell that transmits motor messages, stimulating a muscle or gland.
multiple sclerosis
Literally “many scars”; a disorder characterized by widespread degeneration of myelin.
multipolar neuron
A nerve cell that has many dendrites and a single axon.
myelencephalon or medulla
The posterior part of the hindbrain, continuous with the spinal cord.
myelin
The fatty insulation around an axon, formed by glial cells, that improves the speed of conduction of nerve impulses.
myelination
The process of myelin formation.
neocortex (isocortex) or cortex
Cerebral cortex that is made up of six distinct layers.
nerve
A collection of axons bundled together outside the central nervous system.
neural plasticity
Also called neuroplasticity. The ability of the nervous system to change in response to experience or the environment.
neural tube
An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain.
neuron doctrine
The hypothesis that the brain is composed of separate cells that are distinct structurally, metabolically, and functionally.
neuron or nerve cell
The basic unit of the nervous system, each composed of a cell body, receptive extension(s) (dendrites), and a transmitting extension (axon).
neurotransmitter
Also called synaptic transmitter, chemical transmitter, or simply transmitter. The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons.
Nissl stain
A histological stain that outlines all cell bodies because the dyes are attracted to RNA, which encircles the nucleus.
node of Ranvier
A gap between successive segments of the myelin sheath where the axon membrane is exposed.
norepinephrine
Also called noradrenaline. A neurotransmitter produced and released by sympathetic postganglionic neurons to accelerate organ activity. Also produced in the brainstem and found in projections throughout the brain.
nucleus
Here, a collection of neuronal cell bodies within the central nervous system (e.g., the caudate nucleus).
occipital lobes
Large regions of cortex covering much of the posterior part of each cerebral hemisphere.
olfactory bulb
An anterior projection of the brain that terminates in the upper nasal passages and, through small openings in the skull, provides receptors for smell.
oligodendrocyte
A type of glial cell that forms myelin in the central nervous system.
optical imaging
A method for visualizing brain activity in which near-infrared light is passed through the scalp and skull.
output zone
The part of a neuron, usually corresponding to the axon terminals, at which the cell sends information to another cell.
parallel fiber
One of the axons of the granule cells that form the outermost layer of the cerebellar cortex.
parasympathetic nervous system
A component of the autonomic nervous system that arises from both the cranial nerves and the sacral spinal cord.
parietal lobes
Large regions of cortex lying between the frontal and occipital lobes of each cerebral hemisphere.
peripheral nervous system
The portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord.
pia mater
The innermost of the three meninges that surround the brain and spinal cord.
pons
A portion of the metencephalon; part of the brainstem connecting midbrain to medulla.
positron emission tomography (PET)
A technique for examining brain function by combining tomography with injections of radioactive substances used by the brain.
postcentral gyrus
The strip of parietal cortex, just behind the central sulcus, that receives somatosensory information from the entire body.
posterior cerebral arteries
Two large arteries, arising from the basilar artery, that provide blood to posterior aspects of the cerebral hemispheres, cerebellum, and brainstem.
postganglionic
Literally, “after the ganglion.” Referring to neurons in the autonomic nervous system that run from the autonomic ganglia to various targets in the body.
postsynaptic membrane
The specialized membrane on the surface of the cell that receives information by responding to neurotransmitter from a presynaptic neuron.
postsynaptic
Referring to the region of a synapse that receives and responds to neurotransmitter.
precentral gyrus
The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control.
preganglionic
Literally, “before the ganglion.” Referring to neurons in the autonomic nervous system that run from the central nervous system to the autonomic ganglia.
presynaptic membrane
The specialized membrane of the axon terminal of the neuron that transmits information by releasing neurotransmitter.
presynaptic
Referring to the region of the synapse that releases neurotransmitter.
Purkinje cell
A type of large nerve cell in the cerebellar cortex.
putamen
One of the basal ganglia.
pyramidal cell
A type of large nerve cell that has a roughly pyramid-shaped cell body; found in the cerebral cortex.
receptor
Also called receptor molecule. A protein that captures and reacts to molecules of a neurotransmitter or hormone.
red nucleus
A brainstem structure related to motor control.
reticular formation
An extensive region of the brainstem (extending from the medulla through the thalamus) that is involved in arousal (waking).
ribosomes
Structures in the cell body where genetic information is translated to produce proteins.
sacral
Referring to the 5 spinal segments that make up the lower part of the lower back.
Schwann cell
The glial cell that forms myelin in the peripheral nervous system.
sensory neuron
A neuron that is directly affected by changes in the environment, such as light, odor, or touch.
spinal nerve
Also called somatic nerve. A nerve that emerges from the spinal cord.
stroke
Damage to a region of brain tissue that results from blockage or rupture of vessels that supply blood to that region.
substantia nigra
A brainstem structure in humans that is related to the basal ganglia and is named for its dark pigmentation.
sulcus
A furrow of a convoluted brain surface.
superior colliculi
Paired gray matter structures of the dorsal midbrain that receive visual information and are involved in direction of visual gaze and visual attention to intended stimuli.
Sylvian fissure
Also called lateral sulcus. A deep fissure that demarcates the temporal lobe.
sympathetic chain
A chain of ganglia that runs along each side of the spinal column; part of the sympathetic nervous system.
sympathetic nervous system
A component of the autonomic nervous system that arises from the thoracic and lumbar spinal cord.
synapse
The tiny gap between neurons where information is passed from one to the other.
synaptic cleft
The space between the presynaptic and postsynaptic elements.
synaptic vesicle
A small, spherical structure that contains molecules of neurotransmitter.
tectum
The dorsal portion of the midbrain, including the inferior and superior colliculi.
telencephalon
The frontal subdivision of the forebrain that includes the cerebral hemispheres when fully developed.
temporal lobes
Large lateral cortical regions of each cerebral hemisphere, continuous with the parietal lobes posteriorly, and separated from the frontal lobe by the Sylvian fissure.
thalamus
The brain regions that surround the third ventricle.
third ventricle
The midline ventricle that conducts cerebrospinal fluid from the lateral ventricles to the fourth ventricle.
thoracic
Referring to the 12 spinal segments below the cervical (neck) portion of the spinal cord, corresponding to the chest.
tract
A bundle of axons found within the central nervous system.
transcranial magnetic stimulation (TMS)
Localized, noninvasive stimulation of cortical neurons through the application of strong magnetic fields.
unipolar neuron
Also called monopolar neuron. A nerve cell with a single branch that leaves the cell body and then extends in two directions; one end is the receptive pole, the other end the output zone.
ventral root
The branch of a spinal nerve, arising from the ventral horn of the spinal cord, that carries motor messages from the spinal cord to the peripheral nervous system.
ventricular system
A system of fluid-filled cavities inside the brain.
vertebral arteries
Arteries that ascend the vertebrae, enter the base of the skull, and join together to form the basilar artery.
white matter
A shiny layer underneath the cortex that consists largely of axons with white myelin sheaths.
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