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HB4_nervous system

The nervous system

TermDefinition
absolute refractory period time during an action potential when another action potential cannot be generated because the voltage-gated Na+ channel is inactivated
action potential change in voltage of a cell membrane in response to a stimulus that results in transmission of an electrical signal; unique to neurons and muscle fibers
activation gate part of the voltage-gated Na+ channel that opens when the membrane voltage reaches threshold
astrocyte glial cell type of the CNS that provides support for neurons and maintains the blood-brain barrier
autonomic nervous system (ANS) functional division of the nervous system that is responsible for homeostatic reflexes that coordinate control of cardiac and smooth muscle, as well as glandular tissue
axon hillock portion of the neuron cell body that gives rise to the axon
axon segment single stretch of the axon insulated by myelin and surrounded by nodes of Ranvier at either end (except for the first, which is after the initial segment, and the last, which is followed by the axon terminal)
axon terminal end of the axon, where there are usually several branches extending toward the target cell
axon single process of the neuron that carries an electrical signal (action potential) away from the cell body toward a target cell
biogenic amine class of neurotransmitters that are enzymatically derived from amino acids but no longer contain a carboxyl group
bipolar shape of a neuron with two processes extending from the neuron cell body—the axon and one dendrite
blood-brain barrier (BBB) physiological barrier between the circulatory system and the central nervous system that establishes a privileged blood supply, restricting the flow of substances into the CNS
brain the large organ of the central nervous system composed of white and gray matter, contained within the cranium and continuous with the spinal cord
central nervous system (CNS) anatomical division of the nervous system located within the cranial and vertebral cavities, namely the brain and spinal cord
cerebral cortex outermost layer of gray matter in the brain, where conscious perception takes place
cerebrospinal fluid (CSF) circulatory medium within the CNS that is produced by ependymal cells by filtering the blood
chemical synapse connection between two neurons, or between a neuron and its target, where a neurotransmitter diffuses across a very short distance
cholinergic system neurotransmitter system of acetylcholine, which includes its receptors and the enzyme acetylcholinesterase
continuous conduction slow propagation of an action potential along an unmyelinated axon owing to voltage-gated Na+ channels located along the entire length of the cell membrane
dendrite one of many branchlike processes that extends from the neuron cell body and functions as a contact for incoming signals (synapses) from other neurons or sensory cells
depolarization change in a cell membrane potential from rest toward zero
effector protein enzyme that catalyzes the generation of a new molecule, which acts as the intracellular mediator of the signal that binds to the receptor
electrical synapse connection between two neurons, or any two electrically active cells, where ions flow directly through channels spanning their adjacent cell membranes
ependymal cell glial cell type in the CNS responsible for producing cerebrospinal fluid
excitable membrane cell membrane that regulates the movement of ions so that an electrical signal can be generated
excitatory postsynaptic potential (EPSP) graded potential in the postsynaptic membrane that is the result of depolarization and makes an action potential more likely to occur
G protein guanosine triphosphate (GTP) hydrolase that physically moves from the receptor protein to the effector protein to activate the latter
ganglion localized collection of neuron cell bodies in the peripheral nervous system
gated property of a channel that determines how it opens under specific conditions, such as voltage change or physical deformation
glial cell one of the various types of neural tissue cells responsible for maintenance of the tissue, and largely responsible for supporting neurons
graded potential change in the membrane potential that varies in size, depending on the size of the stimulus that elicits it
gray matter regions of the nervous system containing cell bodies of neurons with few or no myelinated axons; actually may be more pink or tan in color, but called gray in contrast to white matter
inactivation gate part of a voltage-gated Na+ channel that closes when the membrane potential reaches +30 mV
inhibitory postsynaptic potential (IPSP) graded potential in the postsynaptic membrane that is the result of hyperpolarization and makes an action potential less likely to occur
initial segment first part of the axon as it emerges from the axon hillock, where the electrical signals known as action potentials are generated
integration nervous system function that combines sensory perceptions and higher cognitive functions (memories, learning, emotion, etc.) to produce a response
ionotropic receptor neurotransmitter receptor that acts as an ion channel gate, and opens by the binding of the neurotransmitter
leakage channel ion channel that it is opens and is not gated to a specific event, also known as a non-gated channel
ligand-gated channels another name for an ionotropic receptor for which a neurotransmitter is the ligand
mechanically gated channel ion channel that opens when a physical event directly affects the structure of the protein
membrane potential distribution of charge across the cell membrane, based on the charges of ions
metabotropic receptor neurotransmitter receptor that involves a complex of proteins that cause metabolic changes in a cell
microglia glial cell type in the CNS that serves as the resident component of the immune system
multipolar shape of a neuron that has multiple processes—the axon and two or more dendrites
muscarinic receptor type of acetylcholine receptor protein that is characterized by also binding to muscarine and is a metabotropic receptor
myelin sheath lipid-rich layer of insulation that surrounds an axon, formed by oligodendrocytes in the CNS and Schwann cells in the PNS; facilitates the transmission of electrical signals
myelin lipid-rich insulating substance surrounding the axons of many neurons, allowing for faster transmission of electrical signals
nerve cord-like bundle of axons located in the peripheral nervous system that transmits sensory input and response output to and from the central nervous system
neuron neural tissue cell that is primarily responsible for generating and propagating electrical signals into, within, and out of the nervous system
neuropeptide neurotransmitter type that includes protein molecules and shorter chains of amino acids
neurotransmitter chemical signal that is released from the synaptic end bulb of a neuron to cause a change in the target cell
nicotinic receptor type of acetylcholine receptor protein that is characterized by also binding to nicotine and is an ionotropic receptor
node of Ranvier gap between two myelinated regions of an axon, allowing for strengthening of the electrical signal as it propagates down the axon
nonspecific channel channel that is not specific to one ion over another, such as a nonspecific cation channel that allows any positively charged ion across the membrane
nucleus in the central nervous system, a localized collection of neuron cell bodies that are functionally related; a “center” of neural function
oligodendrocyte glial cell type in the CNS that provides the myelin insulation for axons in tracts
peripheral nervous system (PNS) anatomical division of the nervous system that is largely outside the cranial and vertebral cavities, namely all parts except the brain and spinal cord
postsynaptic potential (PSP) graded potential in the postsynaptic membrane caused by the binding of neurotransmitter to protein receptors
process in cells, an extension of a cell body; in the case of neurons, this includes the axon and dendrites
propagation movement of an action potential along the length of an axon
refractory period time after the initiation of an action potential when another action potential cannot be generated
relative refractory period time during the refractory period when a new action potential can only be initiated by a stronger stimulus than the current action potential because voltage-gated K+ channels are not closed
repolarization return of the membrane potential to its normally negative voltage at the end of the action potential
response nervous system function that causes a target tissue (muscle or gland) to produce an event as a consequence to stimuli
resting membrane potential the difference in voltage measured across a cell membrane under steady-state conditions, typically -70 mV
Schwann cell glial cell type in the PNS that provides the myelin insulation for axons in nerves
saltatory conduction quick propagation of the action potential along a myelinated axon owing to voltage-gated Na+ channels being present only at the nodes of Ranvier
sensation nervous system function that receives information from the environment and translates it into the electrical signals of nervous tissue
soma in neurons, that portion of the cell that contains the nucleus; the cell body, as opposed to the cell processes (axons and dendrites)
somatic nervous system (SNS) functional division of the nervous system that is concerned with conscious perception, voluntary movement, and skeletal muscle reflexes
spatial summation combination of graded potentials across the neuronal cell membrane caused by signals from separate presynaptic elements that add up to initiate an action potential
spinal cord organ of the central nervous system found within the vertebral cavity and connected with the periphery through spinal nerves; mediates reflex behaviors
stimulus an event in the external or internal environment that registers as activity in a sensory neuron
summate to add together, as in the cumulative change in postsynaptic potentials toward reaching threshold in the membrane, either across a span of the membrane or over a certain amount of time
synapse narrow junction across which a chemical signal passes from neuron to the next, initiating a new electrical signal in the target cell
synaptic cleft small gap between cells in a chemical synapse where neurotransmitter diffuses from the presynaptic element to the postsynaptic element
synaptic end bulb swelling at the end of an axon where neurotransmitter molecules are released onto a target cell across a synapse
temporal summation combination of several graded potentials at the same location on a neuron resulting in a strong signal from one input
thalamus region of the central nervous system that acts as a relay for sensory pathways
thermoreceptor type of sensory receptor capable of transducing temperature stimuli into neural action potentials
threshold membrane voltage at which an action potential is initiated
tract bundle of axons in the central nervous system having the same function and point of origin
unipolar shape of a neuron which has only one process that includes both the axon and dendrite
voltage-gated channel ion channel that opens because of a change in the charge distributed across the membrane where it is located
white matter regions of the nervous system containing mostly myelinated axons, making the tissue appear white because of the high lipid content of myelin
anterior column white matter between the anterior horns of the spinal cord composed of many different groups of axons of both ascending and descending tracts
anterior horn gray matter of the spinal cord containing multipolar motor neurons, sometimes referred to as the ventral horn
arachnoid mater middle layer of the meninges named for the spider-web–like trabeculae that extend between it and the pia mater
ascending tract central nervous system fibers carrying sensory information from the spinal cord or periphery to the brain
Broca’s area region of the frontal lobe associated with the motor commands necessary for speech production and located only in the cerebral hemisphere responsible for language production, which is the left side in approximately 95 % of the population
brain stem region of the adult brain that includes the midbrain, pons, and medulla oblongata
cauda equina bundle of spinal nerve roots that descend from the lower spinal cord below the first lumbar vertebra and lie within the vertebral cavity; has the appearance of a horse's tail
cerebellum region of the adult brain connected primarily to the pons and is largely responsible for comparing information from the cerebrum with sensory feedback from the periphery through the spinal cord
cerebral cortex outer gray matter covering the brain, marked by wrinkles and folds known as gyri and sulci
cerebral hemisphere one half of the bilaterally symmetrical cerebrum
cerebrum region of the adult brain responsible for higher neurological functions such as memory, emotion, and consciousness
corpus callosum large white matter structure that connects the right and left cerebral hemispheres
cranial nerve one of twelve nerves connected to the brain that are responsible for sensory or motor functions of the head and neck
descending tract central nervous system fibers carrying motor commands from the brain to the spinal cord or periphery
diencephalon region of the adult brain that includes the thalamus and hypothalamus
dorsal (posterior) nerve root axons entering the posterior horn of the spinal cord
dorsal (posterior) root ganglion sensory ganglion attached to the posterior nerve root of a spinal nerve
dura mater tough, fibrous, outer layer of the meninges that is attached to the inner surface of the cranium and vertebral
endoneurium innermost layer of connective tissue that surrounds individual axons within a nerve
epineurium outermost layer of connective tissue that surrounds an entire nerve
fascicle small bundles of axons or muscle fibers enclosed by connective tissue
frontal lobe region of the cerebral cortex directly beneath the frontal bone of the cranium
hypothalamus major region of the diencephalon that is responsible for coordinating autonomic and endocrine control of homeostasis
kinesthesia general sensory perception of movement of the body
lateral column white matter of the spinal cord between the posterior horn on one side and the axons from the anterior horn on the same side
lateral horn region of the spinal cord gray matter in the thoracic, upper lumbar, and sacral regions that is the central component of the sympathetic division of the autonomic nervous system
longitudinal fissure large separation along the midline between the two cerebral hemispheres
meninges protective outer coverings of the CNS composed of connective tissue
occipital lobe region of the cerebral cortex directly beneath the occipital bone of the cranium
olfaction special sense responsible for smell, which has a unique, direct connection to the cerebrum
olfactory nerve first cranial nerve; responsible for the sense of smell
optic nerve second cranial nerve; responsible for visual sensation
paravertebral ganglia autonomic ganglia superior to the sympathetic chain ganglia
parietal lobe region of the cerebral cortex directly beneath the parietal bone of the cranium
perineurium layer of connective tissue surrounding fascicles within a nerve
pia mater thin, innermost membrane of the meninges that directly covers the surface of the CNS
posterior columns white matter of the spinal cord that lies between the posterior horns of the gray matter, sometimes referred to as the dorsal column; composed of axons of ascending tracts that carry sensory information up to the brain
posterior horn gray matter region of the spinal cord in which sensory input arrives, sometimes referred to as the dorsal horn
prefrontal lobe specific region of the frontal lobe anterior to the more specific motor function areas, which can be related to the early planning of movements and intentions to the point of being personality-type functions
proprioception general sensory perceptions providing information about location and movement of body parts; the “sense of the self”
somatosensation general senses related to the body, usually thought of as the senses of touch, which would include pain, temperature, and proprioception
spinal nerve one of 31 nerves connected to the spinal cord
subarachnoid space space between the arachnoid mater and pia mater that contains CSF and the fibrous connections of the arachnoid trabeculae
subcortical nucleus all the nuclei beneath the cerebral cortex, including the basal nuclei and the basal forebrain
sympathetic chain ganglia autonomic ganglia in a chain along the anterolateral aspect of the vertebral column that are responsible for contributing to homeostatic mechanisms of the autonomic nervous system
temporal lobe autonomic ganglia in a chain along the anterolateral aspect of the vertebral column that are responsible for contributing to homeostatic mechanisms of the autonomic nervous system
terminal ganglion autonomic ganglia that are near or within the walls of organs that are responsible for contributing to homeostatic mechanisms of the autonomic nervous system
thalamus major region of the diencephalon that is responsible for relaying information between the cerebrum and the hindbrain, spinal cord, and periphery
vagus nerve tenth cranial nerve; responsible for the autonomic control of organs in the thoracic and upper abdominal cavities
ventral (anterior) nerve root axons emerging from the anterior or lateral horns of the spinal cord
ventricles spaces for cerebrospinal fluid to circulate through the brain
acetylcholine (ACh) neurotransmitter that binds at a motor end-plate to trigger depolarization
adrenal medulla interior portion of the adrenal (or suprarenal) gland that releases epinephrine and norepinephrine into the bloodstream as hormones
adrenergic synapse where norepinephrine is released, which binds to α- or β-adrenergic receptors
cholinergic synapse at which acetylcholine is released and binds to the nicotinic or muscarinic receptor
collateral ganglia ganglia outside of the sympathetic chain that are targets of sympathetic preganglionic fibers, which are the celiac, inferior mesenteric, and superior mesenteric ganglia
craniosacral system alternate name for the parasympathetic division of the autonomic nervous system that is based on the anatomical location of central neurons in brain-stem nuclei and the lateral horn of the sacral spinal cord; also referred to as craniosacral outflow
epinephrine signaling molecule released from the adrenal medulla into the bloodstream as part of the sympathetic response
fight-or-flight response set of responses induced by sympathetic activity that lead to either fleeing a threat or standing up to it, which in the modern world is often associated with anxious feelings
G protein–coupled receptor membrane protein complex that consists of a receptor protein that binds a G protein—that is activated by that binding and in turn activates an effector protein (enzyme) that creates a second-messenger molecule in the cytoplasm of the target cell
ganglionic neuron specifically refers to the cell body of a neuron in the autonomic system that is located in a ganglion
muscarinic receptor type of acetylcholine receptor protein that is characterized by also binding to muscarine and is a metabotropic receptor
nicotinic receptor type of acetylcholine receptor protein that is characterized by also binding to nicotine and is an ionotropic receptor
norepinephrine signaling molecule released as a neurotransmitter by most postganglionic sympathetic fibers as part of the sympathetic response, or as a hormone into the bloodstream from the adrenal medulla
parasympathetic division division of the autonomic nervous system responsible for restful and digestive functions
postganglionic fiber axon from a ganglionic neuron in the autonomic nervous system that projects to and synapses with the target effector; sometimes referred to as a postganglionic neuron
preganglionic fiber axon from a central neuron in the autonomic nervous system that projects to and synapses with a ganglionic neuron; sometimes referred to as a preganglionic neuron
rest and digest set of functions associated with the parasympathetic system that lead to restful actions and digestion
sympathetic chain ganglia series of ganglia adjacent to the vertebral column that receive input from central sympathetic neurons
sympathetic division division of the autonomic nervous system associated with the fight-or-flight response
terminal ganglia ganglia of the parasympathetic division of the autonomic system, which are located near or within the target effector, the latter also known as intramural ganglia
thoracolumbar system alternate name for the sympathetic division of the autonomic nervous system that is based on the anatomical location of central neurons in the lateral horn of the thoracic and upper lumbar spinal cord
Created by: SaraLUNEX