afferent division
The portion of the peripheral nervous system that carries information from the periphery to the central nervous system
afferent neuron
Neuron that possesses a sensory receptor at its peripheral ending and carries information to the central nervous system
ascending tract
A bundle of nerve fibers of similar function that travels up the spinal cord to transmit signals derived from afferent input to the brain
astrocyte
A type of glial cell in the brain; major functions include holding the neurons together in proper spatial relationship, inducing the brain capillaries to form tight junctions important in the blood-brain barrier, and enhancing synaptic activity
autonomic nervous system
The portion of the efferent division of the peripheral nervous system that innervates smooth and cardiac muscle and exocrine glands; subdivided into the sympathetic and the parasympathetic nervous systems
basal nuclei
Several masses of gray matter located deep within the white matter of the cerebrum of the brain; play an important inhibitory role in motor control
blood-brain barrier (BBB)
Special structural and functional features of the brain capillaries that limit access of materials from the blood into the brain tissue
brain stem
The portion of the brain that is continuous with the spinal cord, serves as an integrating link between the spinal cord and higher brain levels, and controls many life-sustaining processes, such as breathing, circulation, and digestion
center
A functional collection of cell bodies within the central nervous system
central nervous system (CNS)
The brain and spinal cord
central sulcus
A deep infolding of the brain surface that runs roughly down the middle of the lateral surface of each cerebral hemisphere and separates the parietal and frontal lobes
cerebellum
The part of the brain attached at the rear of the brain stem and concerned with maintaining proper position of the body in space and subconscious coordination of motor activity
cerebral cortex
The outer shell of gray matter in the cerebrum; site of initiation of all voluntary motor output and final perceptual processing of all sensory input as well as integration of most higher neural activity
cerebral hemispheres
The cerebrum's two halves, which are connected by a thick band of neuronal axons
cerebrospinal fluid (CSF)
A special cushioning fluid that is produced by, surrounds, and flows through the central nervous system
cerebrum
The division of the brain that consists of the basal nuclei and cerebral cortex
corpus callosum
The thick band of nerve fibers that connects the two cerebral hemispheres structurally and functionally
cranial nerves
The 12 pairs of peripheral nerves, the majority of which arise from the brain stem
descending tract
A bundle of nerve fibers of similar function that travels down the spinal cord to relay
messages from the brain to efferent neurons
diencephalon
The division of the brain that consists of the thalamus and hypothalamus
dorsal root ganglion
A cluster of afferent neuronal cell bodies located adjacent to the spinal cord
effector organs
The muscles or glands innervated by the nervous system that carry out the nervous system's orders to bring about a desired effect, such as a particular movement or secretion
effector division
The portion of the peripheral nervous system that carries instructions from the central nervous system to effector organs
efferent neuron
Neuron that carries information from the central nervous system to an effector organ
electroencephalogram (EEG)
A graphic record of the collective postsynaptic potential activity in the cell bodies and dendrites located in the cortical layers of the brain under a recording electrode
enteric nervous system
The extensive network of nerve fibers consisting of the myenteric plexus and submucous plexus within the digestive tract wall that endows the tract with considerable self-regulation
ependymal cells
The glial cells lining the ventricles of the brain, which serve as neural stem cells
frontal lobes
The lobes of the cerebral cortex at the top of the brain in front of the central sulcus, which are responsible for voluntary motor output, speaking ability, and elaboration of thought
glial cells
Connective tissue cells of the CNS, which support the neurons both physically and metabolically, including astrocytes, oligodendrocytes, ependymal cells, and microglia
gray matter
The portion of the central nervous system composed primarily of densely packaged neuronal cell bodies and dendrites
hippocampus
The elongated, medial portion of the temporal lobe that is a part of the limbic system and is especially crucial for forming long-term memories
hypothalamus
The brain region beneath the thalamus that regulates many aspects of the internal fluid environment, such as water and salt balance and food intake; serves as an important link between the autonomic nervous system and endocrine system
interneuron
Neuron that lies entirely within the central nervous system and is important for integrating peripheral responses to peripheral information as well as for the abstract phenomena associated with the "mind
limbic system
A functionally interconnected ring of forebrain structures that surrounds the brain stem and is concerned with emotions, basic survival and sociosexual behavioral patterns, motivation, and learning
meninges
Three membranes that wrap the brain and spinal cord
microglia
The type of glial cells that serve as the immune defense cells of the CNS
nerve
A bundle of peripheral neuronal axons, some afferent and some efferent, enclosed by a connective tissue covering and following the same pathway
nervous system
One of the two major regulatory systems of the body; in general, coordinates rapid activities of the body, especially those involving interactions with the external environment
nucleus (of brain)
A functional aggregation of neuronal cell bodies within the brain
occipital lobes
The posterior lobes of the cerebral cortex, which initially process visual input
oligodendrocytes
The myelin-forming cells of the central nervous system
parasympathetic nervous system
The subdivision of the autonomic nervous system that dominates in quiet, relaxed situations and promotes body maintenance activities such as digestion and emptying of the urinary bladder
parietal lobes
The lobes of the cerebral cortex that lie at the top of the brain behind the central sulcus, which contain the somatosensory cortex
peripheral nervous system (PNS)
Nerve fibers that carry information between the central nervous system and other parts of the body
primary motor cortex
The portion of the cerebral cortex that lies anterior to the central sulcus and is responsible for voluntary motor output
proprioception
Awareness of position of body parts in relation to one another and to surroundings
reflex
Any response that occurs automatically without conscious effort; the components of a reflex arc include a receptor, afferent pathway, integrating center, efferent pathway, and effector
reticular activating system (RAS)
Ascending fibers that originate in the reticular formation and carry signals upward to arouse and activate the cerebral cortex
reticular formation
A network of interconnected neurons that runs throughout the brain stem and initially receives and integrates all synaptic input to the brain
sensory input
Input from somatic sensation and special senses
sensory receptor
An afferent neuron's peripheral ending, which is specialized to respond to a particular stimulus in its environment
somatic nervous system
The portion of the efferent division of the peripheral nervous system that innervates skeletal muscles; consists of the axonal fibers of the alpha motor neurons
somatosensory cortex
The region of the parietal lobe immediately behind the central sulcus; the site of initial processing of somesthetic and proprioceptive input
somesthetic sensations
Awareness of sensory input such as touch, pressure, temperature, and pain from the body's surface
spinal reflex
A reflex that is integrated by the solution from the pancreas and liver spinal cord
stimulus
A detectable physical or chemical change in the environment of a sensory receptor
stretch reflex
A monosynaptic reflex in which an afferent neuron originating at a stretch-detecting receptor in a skeletal muscle terminates directly on the efferent neuron supplying the same muscle to cause it to contract and counteract the stretch
subcortical regions
The brain regions that lie under the cerebral cortex, including the basal nuclei, thalamus, and hypothalamus
sympathetic nervous system
The subdivision of the autonomic nervous system that dominates in emergency ("fight-or-flight") or stressful situations and prepares the body for strenuous physical activity
temporal lobes
The lateral lobes of the cerebral cortex, which initially process auditory input
temporal summation
The summing of several postsynaptic potentials that occur very close together in time because of successive firing of a single presynaptic neuron
thalamus
The brain region that serves as a synaptic integrating center for preliminary processing of all sensory input on its way to the cerebral cortex
tract
A bundle of nerve fibers (axons of long interneurons) with a similar function within the spinal cord
vagus nerve
The tenth cranial nerve, which serves as the major parasympathetic nerve
ventricle (of brain)
One of four interconnected chambers within the brain through which cerebrospinal fluid flows
white matter
The portion of the central nervous system composed of myelinated nerve fibers