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185 Cards in this Set

  • Front
  • Back
Brain region below thalamus; responsible for integration of many basic neural, endocrine, and behavioral functions, especially those concerned with regulation of internal environment
Limbic system
Interconnected brain structures in cerebrum; involved with emotions and learning
Reticular formation
(reticular activating center) – extensive neuron network extending through brainstem core; receives and integrates information from many afferent pathways and from other CNS regions.
Cranial nerves
One of 24 peripheral nerves (12 pairs) that join brainstem or forebrain with structures outside CNS
Dorsal root
Group of afferent nerve fibers that enters dorsal region of spinal cord
Dorsal root ganglia
Group of sensory nerve cell bodies that have axons projecting to the dorsal horn of the spinal cord.
Ventral root
One of two groups of efferent fibers that leave ventral side of spinal cord.
Spinal nerve
One of 86 peripheral nerves (43 pairs) that join spinal cord
Central nervous system (CNS)
Brain plus spinal cord
Peripheral nervous system
Nerve fibers extending from CNS.
Neuron (Nerve cell)
Cell in nervous system specialized to initiate, integrate, and conduct electrical signals
Chemical messenger used by neurons to communicate with each other or with effectors
Integrators (Integrating center)
Cells that receive one or more signals and send out appropriate response
Long extension from neuron cell body
Cell body (soma)
In cells with long extensions, the part that contains the nucleus
Highly branched extension of neuron cell body; receives synaptic input from other neurons
Extension from neuron cell body; propagates action potentials away from cell body; also called a nerve fiber
Nerve fiber
axon of a neuron
Initial segment (axon hillock)
first portion of axon plus the part of the cell body where axon arises
Branch of a nerve axon
Axon terminal
End of axon; forms synaptic or neuroeffector junction with postjunctional cell
swollen region of axon; contains neurotransmitter-filled vesicles; analogous to presynaptic ending
insulating material covering axons of many neurons; consists of layers of myelin-forming cell plasma membrane wrapped around axon
type of glial cell; responsible for myelin formation in CNS
Schwann cells
nonneural cell that forms myelin sheath in peripheral nervous system
Nodes of Ranvier
space between adjacent myelin-forming cells along myelinated axon where axonal plasma membrane is exposed to extracellular fluid
Axon transport
Process involving intracellular filaments by which materials are moved from one end of axon to other
Afferent neurons
Neuron that carries information from sensory receptors at its peripheral endings to CNS; cell body lies outside CNS.
Efferent neurons
neuron that carries information away from CNS
neuron whose cell body and axon lie entirely in CNS
Sensory receptors
a cell or portion of a cell that contains structures or chemical molecules sensitive to changes in an energy form in the outside world or internal environment; in response to activation by this energy, the sensory receptor initiates action potentials in that cell or an adjacent one.
Group of many nerve fibers traveling together in peripheral nervous system.
anatomically specialized junction between two neurons where electrical activity in one neuron influences excitability of second; see also chemical synapse, electrical synapse, excitatory synapse, inhibitory synapse
Presynaptic neuron
Neuron that conducts action potentials toward a synapse
Postsynaptic neuron
Neuron that conducts information away from a synapse
Glial cells
nonneuronal cell in CNS; helps regulate extracellular environment of CNS; also called neuroglia
a form of glial cell that regulates composition of extracellular fluid around neurons and forms the blood-brain barrier
a type of glial cell that acts as a macrophage
Stem cells
cell that in adult body divides continuously and forms supply of cells for differentiation
Growth cone
tip of developing axon
Neurotropic factors
protein that stimulates growth and differentiation of some neurons.
Electric potential (potential)
voltage difference between two points; see also action potential, graded potential
Potential difference (potential)
A difference in charge between two points
movement of electric charge; in biological systems, this is achieved by ion movement.
Resistance (R)
hindrance to movement through a particular substance, tube, or opening
Ohm’s Law
current (I) is directly proportional to voltage (E) and inversely proportional to resistance (R) such that I = E / R
Resting membrane potential
voltage difference between inside and outside of cell in absence of excitatory or inhibitory stimulation; also called resting potential
Equilibrium potential
voltage gradient across a membrane that is equal in force but opposite in direction to concentration force affecting a given ion species.
Nernst equation
calculation for electrochemical equilibrium across a membrane for any single ion
Goldman equation
calculation for electrochemical equilibrium when a membrane is permeable to more than one ion
Leak potassium channels
potassium channels that are open when a membrane is at rest
Electrogenic pump
active transport system that directly separates electrical charge, thereby producing a potential difference
to change membrane potential value toward zero so that cell interior becomes less negative than resting level
part of the action potential in which the membrane potential goes above zero.
return transmembrane potential to its resting level
to change membrane potential so cell interior becomes more negative than its resting state
Graded potentials
membrane potential change of variable amplitude and duration that is conducted decrementally; has no threshold or refractory period
increase in muscle tension or shortening in response to rapid, repetitive stimulation relative to single twitch
Action potentials
electrical signal propagated by nerve and muscle cells; an all-or-none depolarization of membrane polarity; has a threshold and refractory period and is conducted without decrement
Excitable membranes
membrane capable of producing action potentials
ability to produce electric signals
Threshold potential (threshold)
membrane potential to which excitable membrane must be depolarized to initiate an action potential.
decrease in membrane potential in neurons at the end of the action potential
Positive feedback
characteristic of control systems in which an initial disturbance sets off train of events that increases the disturbance even further; compare negative feedback
Inactivation gate
portion of the voltage-gated sodium or potassium channel that closes the channel
Threshold stimuli
stimulus capable of depolarizing membrane just to threshold
Subthreshold potentials
depolarization less than threshold potential
Subthreshold stimuli
stimulus capable of depolarizing membrane but not by enough to reach threshold
pertaining to event that occurs maximally or not at all
Absolute refractory period
time during which an excitable membrane cannot generate an action potential in response to any stimulus.
Efferent division (PNS)
Neurons in the peripheral nervous system that project out of the central nervous system.
Relative refractory period
time during which excitable membrane will produce action potential but only to a stimulus of greater strength than the usual threshold strength.
Action potential propagation
Every new action potential produces local currents of its own, which depolarize the region adjacent to it, producing yet another action potential at the next site, and so on to cause action potential propagation along the length of the membrane.
Saltatory conduction
propagation of action potentials along a myelinated axon such that the action potentials jump from one node of Ranvier in the myelin sheath to the next node
Receptor potential
graded potential that arises in afferent neuron ending, or a specialized cell intimately associated with it, in response to stimulation.
Synaptic potential
see postsynaptic potential -
Pacemaker potential
neurons that set rhythm of biological clocks independent of external cues; any nerve or muscle cell that has an inherent autorhythmicity and determines activity pattern of other cells
Excitatory synapse
synapse that, when activated, increases likelihood that postsynaptic neuron will undergo action potentials or increases frequency of existing action potentials.
Inhibitory synapse
synapse that, when activated, decreases likelihood that postsynaptic neuron will fire an action potential (or decrease frequency of existing action potentials)
(neuronal) many presynaptic neurons synapsing upon one postsynaptic neuron; (of eyes) turning of eyes inward (that is, toward nose) to view near objects
(neuronal) one presynaptic neuron synapsing upon many postsynaptic neurons; (of eyes) turning of eyes outward to view distant objects
Electrical synapse
synapse at which local currents resulting from electrical activity flow between two neurons through gap junctions joining them.
Chemical synapse
synapse at which neurotransmitters released by one neuron diffuse across an extracellular gap to influence a second neuron's activity
Synaptic vesicles
cellular structure that holds and releases neurotransmitter at the synapse
Postsynaptic density
area in the postsynaptic cell membrane that contains neurotransmitter receptors and structural proteins important for synapse function
Synaptic cleft
narrow extracellular space separating pre- and postsynaptic neurons at chemical synapse
chemical messenger released with a neurotransmitter from synapse or neuroeffector junction
SNARE proteins
proteins in the nerve terminal involved in moving synaptic vesicles to the nerve terminal for release of neurotransmitter into the synaptic cleft
protein present in wall of synaptic vesicle that binds calcium and helps stimulate the process of exocytosis
Synaptic delay
length of time it takes for electrical changes to move from the presynaptic to the postsynaptic membrane
active process that recaptures excess secreted neurotransmitter back into the presynaptic cell; can be inhibited with drugs
Excitatory postsynaptic potential (EPSP)
depolarizing graded potential in postsynaptic neuron in response to activation of excitatory synapse
Inhibitory postsynaptic potential (IPSP)
hyperpolarizing graded potential that arises in postsynaptic neuron in response to activation of inhibitory synaptic endings upon it
Temporal summation
membrane potential produced as two or more inputs, occurring at different times, are added together; potential change is greater than that caused by single input
Spatial summation
adding together effects of simultaneous inputs to different places on a neuron to produce potential change greater than that caused by single input
Axo-axonic synapse
presynaptic synapse where an axon stimulates the presynaptic terminal of another axon
Presynaptic inhibition
inhibitory input to neurons through synapses at the nerve terminal
Presynaptic facilitation
excitatory input to neurons through synapses at the nerve terminal
receptors on a cell affected by a chemical messenger released from the same cell
Receptor desensitization
temporary inability of a receptor to respond to its ligand due to prior ligand binding
chemical messenger that binds to receptor and triggers cell's response; often refers to drug that mimics action of chemical normally in the body
(drug) molecule that competes with another for a receptor and binds to the receptor but does not trigger the cell's response
chemical messenger that acts on neurons, usually by a second-messenger system, to alter response to a neurotransmitter
Acetylcholine (Ach)
a neurotransmitter released by pre- and post-ganglionic parasympathetic neurons, preganglionic sympathetic neurons, somatic neurons, and some CNS neurons
pertaining to acetylcholine; a compound that acts like acetylcholine
enzyme that breaks down acetylcholine into acetic acid and choline
Nicotinic receptors
acetylcholine receptor that responds to nicotine; primarily, receptors at motor end plate and on postganglionic autonomic neurons
Muscarinic receptors
acetylcholine receptor that responds to the mushroom poison muscarine; located on smooth muscle, cardiac muscle, some CNS neurons, and glands
Biogenic amines
one of family of neurotransmitters having basic formula R-NH2; includes dopamine, norepinephrine, epinephrine, serotonin, and histamine
biogenic amine (catecholamine) neurotransmitter and hormone; precursor of epinephrine and norepinephrine; see also prolactin-inhibiting hormone
Norepinephrine (NE)
biogenic amine (catecholamine) neurotransmitter released at most sympathetic postganglionic endings, from adrenal medulla, and in many CNS regions
Epinephrine (E)
amine hormone secreted by adrenal medulla and involved in regulation of organic metabolism; a biogenic amine (catecholamine) neurotransmitter; also called adrenaline
dopamine, epinephrine, or norepinephrine, all of which have similar chemical structures
L-dihydroxyphenylalanine; precursor to dopamine formation
Monoamine oxidase (MAO)
enzyme that breaks down catecholamines in nerve terminal and synapse
pertaining to norepinephrine or epinephrine; compound that acts like norepinephrine or epinephrine
referring to neurons that release norepinephrine as a neurotransmitter or membrane receptors that bind norepinephrine
Alpha-adrenergic receptors
one type of plasma-membrane receptor for epinephrine and norepinephrine; also called alpha adrenoceptor; compare beta-adrenergic receptor
Beta-adrenergic receptors
a type of plasma membrane receptor for epinephrine and norepinephrine; compare alpha-adrenergic receptor; also called beta adrenoceptor
Metabotropic receptor
membrane receptor in neurons that initiates formation of second messengers when bound with ligand
biogenic amine neurotransmitter; paracrine agent in blood platelets and digestive tract; also called 5-hydroxytryptamine, or 5-HT
Excitatory amino acids
amino acid that acts as an excitatory (depolarizing) neurotransmitter in the nervous system
anion formed from the amino acid glutamic acid; a major excitatory CNS neurotransmitter
an excitatory neurotransmitter in CNS; ionized form of the amino acid aspartic acid
Ionotropic receptors
membrane receptor in neurons that is an ion channel that is opened by binding of its ligand
n-methyl-d-aspartate (NMDA)
ionotropic glutamate receptor involved in learning and memory
GABA (gamma-aminobutyric acid)
major inhibitory neurotransmitter in CNS
an amino acid; a neurotransmitter at some inhibitory synapses in CNS
family of more than 50 neurotransmitters composed of 2 or more amino acids; often also functions as chemical messenger in nonneural tissues
neuron that releases peptides
Endogenous opioids-beta-endorphin
certain neuropeptides – endorphin, dynorphic, and enkephalin
Certain neuropeptides, termed endogenous opioids-beta-endorphin, the dynorphins, and the enkephalins – have attracted much interest because their receptors are the sites of action of opiate drugs such as morphine and codeine.
peptide neurotransmitter at some synapses activated by opiate drugs; an endogenous opioid
Substance P
neuropeptide neurotransmitter released by afferent neurons in pain pathway as well as other sites.
Nitric oxide
A gas that functions as intercellular messenger, including neurotransmitters; is endothelium-derived relaxing factor; destroys intracellular microbes.
Carbon monoxide
CO; gas that reacts with hemoglobin; decreases blood oxygen-carrying capacity and shifts oxygen-hemoglobin dissociation curve to the left; also acts as an intracellular messenger in neurons.
adenosine triphosphate (ATP)
major molecule that transfers energy from metabolism to cell functions during its breakdown to ADP and release of Pi
one of the four bases making up DNA; also a breakdown product of ATP used as a neurotransmitter
Pathway (tract)
series of connected nerves that move a particular type of information from one part of the brain to another part
Bundle of nerve fibers linking right and left halves of the brain.
Part of the brain that, with diencephalons, forms the forebrain
Core of anterior part of brain; lies beneath cerebral hemispheres and contains thalamus and hypothalamus.
brain subdivision consisting of medulla oblongata, pons, and midbrain and located between spinal cord and forebrain
Brain subdivision lying behind forebrain and above brainstem; deals with muscle movement control.
Large, anterior brain subdivision consisting of right and left cerebral hemispheres (the cerebrum) and diencephalons.
The most rostral section of the brainstem.
large area of the brainstem containing many nerve axons
Medulla oblongata
Part of the brain stem closest to the spinal cord
Cerebral ventricles
One of four interconnected spaces in the brain; filled with cerebrospinal fluid.
Cerebral hemispheres
Either left or right half of the cerebral cortex
Cerebral cortex
Cellular layer covering the cerebrum
Gray matter
area of brain and spinal cord that appears gray in unstained specimens and consists mainly of cell bodies and unmyelinated portions of nerve fibers
White matter
Portion of CNS that appears white in unstained specimens and contains primarily myelinated nerve fibers
Subcortical nuclei
groups of cells in brain below the cerebral cortex
Corpus callosum
Wide band of nerve fibers connecting the two cerebral hemispheres; a brain commissure.
Frontal lobe
Region of anterior cerebral cortex where motor areas, Broca’s speech center, and some association cortex are located
Parietal lobe
Region of cerebral cortex containing sensory cortex and some association cortex.
Occipital lobe
Posterior region of cerebral cortex where primary visual cortex is located
Temporal lobe
Region of cerebral cortex where primary auditory cortex and Wernicke’s speech center are located.
Pyramidal cells
Large neuron with characteristic pyramid-shaped cell body and apical dendrite
Basal nuclei (Basal ganglia)
Nuclei deep in cerebral hemispheres that code and relay information associated with control of body movements; specifically, caudate nucleus, globus passidus, and putamen; also called basal ganglia
Subdivision of diencephalons; integrating center for sensory input on its way to cerebral cortex; also contains motor nuclei
Afferent division (PNS)
Neurons in the peripheral nervous system that project to the central nervous system
Somatic nervous system
Component of efferent division of peripheral nervous system; innervates skeletal muscle; compare autonomic nervous system.
Autonomic nervous system
Component of efferent division of peripheral nervous system that consists of sympathetic and parasympathetic subdivisions; innervates cardiac muscle, smooth muscle, and glands; compare somatic nervous system.
Motor neurons
Somatic efferent neuron, which innervates skeletal muscle.
Enteric nervous system
Neural network residing in and innervating walls of gastrointestinal tract.
Autonomic ganglion
Group of neuron cell bodies in the peripheral nervous system.
Autonomic-nervous-system neuron or nerve fiber whose cell body lies in CNS and whose axon terminals lie in a ganglion; conducts action potentials from CNS to ganglion; compare postganglionic
Autonomic-nervous-system neuron or nerve fiber whose cell body lies in a ganglion; conducts impulses away from ganglion toward periphery; compare preganglionic
Sympathetic division
Portion of autonomic nervous system whose preganglionic fibers leave CNS at thoracic and lumbar portions of spinal cord; compare parasympathetic division
Parasympathetic division
Portion of the autonomic nervous system whose preganglionic fibers leave CNS from brainstem and sacral portion of spinal cord; most of its postganglionic fibers release acetylcholine; compare sympathetic division.
Sympathetic trunk
One of paired chains of interconnected sympathetic ganglia that lie on either side of vertebral column.
Adrenal medulla
Endocrine gland that forms inner core of each adrenal gland; secretes amine hormones, mainly epinephrine, compare adrenal cortex
Dual innervation
Innervation of an organ or gland by both sympathetic and parasympathetic nerve fibers.
Fight-or-flight response
Activation of sympathetic nervous system during stress
Homeostatic state characteristic of parasympathetic nervous system activation
Protective membranes that cover brain and spinal cord
Dura mater
Thick, outermost membrane (meninges) covering the brain.
The middle of three membranes (meninges) covering the brain.
Pia mater
Innermost of three membranes (meninges) covering the brain.
Subarachnoid space
Space between the arachnoid and pia mater meninges containing cerebrospinal fluid.
Cerebrospinal fluid (CSF)
Fluid that fills cerebral ventricles and the subarachnoid space surrounding brain and spinal cord
Choroid plexus
Highly vascular epithelial structure lining portions of cerebral ventricles; responsible for much of cerebrospinal fluid formation.
Blood-brain barrier
Group of anatomical barriers and transport systems in brain capillary endothelium that controls kinds of substances entering brain extracellular space from blood and their rates of entry.