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222 Cards in this Set
- Front
- Back
skeletal muscle |
bundles of long multinucleated cells with cross-striations; contraction is quick, forceful, voluntary control |
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cardiac muscle |
cross-striations, elongated and branched cells bound at intercalated discs; contraction involuntary, vigorous, rhythmic |
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intercalated discs |
dark-staining transverse lines that cross the chains of cardiac cells at irregular intervals where the cells join, contain many junctional complexes |
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smooth muscle |
collections of fusiform cells with no striations; contractions slow and involuntary |
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sarcoplasm |
cytoplasm of muscle cells |
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sarcoplasmic reticulum |
smooth endoplasmic reticulum of muscle cells, specialized for Ca ion sequestration |
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sarcolemma |
muscle cell membrane and external lamina |
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muscle fibers |
long, cylindrical multinucleated cells with diameters of 10 to 100 um |
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satellite cells |
reserve muscle progenitor cells that sit adjacent to most differentiated skeletal muscle fibers |
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epimysium |
external sheath of dense CT that surrounds the entire muscle- brings large nerves, blood vessels, and lymphatics |
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perimysium |
thin CT layer that surrounds each fascicle |
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fascicle |
bundle of muscle fibers- functional unit in which fibers work together |
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endomysium |
thin layer of reticular fibers and scattered fibroblasts that surrounds external lamina of individual muscle fibers- brings nerve fibers and capillaries |
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myotendinous junction |
where epimysium is continuous with the dense regular CT of a tendon |
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A bands |
anisotropic/birefringent/dark in EM, consist of thick filaments and overlapping thin filaments, |
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I bands |
isotropic/light in EM, consist of the portions of the thin filaments that do not overlap the thick filaments, have titin and nebulin |
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Z disc |
dark band that bisects I band |
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sarcomere |
repetitive functional subunit of the contractile apparatus- Z disc to Z disc |
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myofribrils |
cylindrical filament bundles in the sarcoplasm, consisting of an end-to-end arrangement of sarcomeres |
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myofilaments |
thick and thin filaments in the sarcoplasm composed of myosin and F-actin |
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myosin |
large complex with two identical heavy chains and two pairs of light chains |
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actomyosin ATPase activity |
the function of myosin when it binds ATP and catalyzes energy release |
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alpha-actinin |
actin binding protein that anchors actin filaments on the Z disc |
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tropomyosin |
long coil of two polypeptide chains located in the groove between the two twisted actin strands |
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troponin |
complex of three subunits: TnT- attaches to tropomyosin, TnC- binds Calcium ions, TnI- regulates actin-myosin interactions |
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titin |
largest protein in the body, has scaffolding and elastic properties, supports the thick myofilaments and connects them to the Z disc |
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nebulin |
large accessory protein that binds each thin myofilament laterally, helps anchor them to alpha-actinin, and specifies length of the actin polymers during myogenesis |
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H zone |
lighter staining zone in A band where only rodlike portions of myosin lie and there are no thin filaments, bisected by M line |
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M line |
line that bisects the H zone and contains a myomesin and creatine kinase |
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myomesin |
myosin-binding protein found in M line, holds thick filaments in place |
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creatine kinase |
enzyme that catalyzes transfer of phosphate groups from phosphocreatine to ADP to supply ATP for muscle contraction, found in M line |
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transverse/T tubules |
long invaginations of cell membrane that encircle every myofibril near the aligned A and I band boundaries and cause uniform contraction of all myofibrils |
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terminal cisterns |
expanded cisterns on either side of the t tubule that store concentrated calcium ions |
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triad |
t tubule and two terminal cisterns |
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rigor mortis |
rigidity of skeletal muscles after death when mitochondrial activity stops, removing ATP and making actin-myosin crossbridges stable |
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motor end plate |
synaptic structure where the axonal branch forms a dilated termination in a trough on the muscle cell surface |
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acetylcholine |
neurotransmitter located in synaptic vesicles |
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synaptic cleft |
space between the axon and the muscle |
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junctional folds |
folds in the sarcolemma that add postsynaptic surface area and transmembrane acetylcholine receptors |
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acetylcholine receptor |
receptor on the sarcolemma that binds acetylcholine and has a nonselective cation channel that allows the influx of sodium ions, depolarizes the sarcolemma, and produces the muscle action potential |
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acetylcholinesterase |
extracellular enzyme that removes free acetylcholine after the muscle contraction |
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motor unit |
an axon and all the muscle fibers in contact with its branches |
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muscle spindles |
stretch detectors in muscle fascicles, encapsulated by modified perimysium, has concentric layers of flattened cells, interstitial fluid, and intrafusal fibers |
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intrafusal fibers |
thin muscle fibers in muscle spindles with nuclei |
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Golgi tendon organs |
smaller encapsulated structures that enclose sensory axons that penetrate myotendinous junctions, detecting changes in tendon tensions |
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myoglobin |
cytoplasmic protein abundant in slow, oxidative muscle fibers that contains iron and stores oxygen molecules |
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caveolae |
short membrane invaginations of smooth muscle cells |
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calmodulin |
alternative to troponin in smooth muscle cells |
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myosin light-chain kinase |
Calcium ion-sensitive kinase involved in contractile mechanism |
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dense bodies |
bodies associated with the sarcolemma and cytoplasm of smooth muscle cells that have alpha-actinin and are functionally similar to Z discs in skeletal muscle |
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neurons |
nerve cells, which have numerous long processes |
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glial cells |
cells that support and protect neurons, have short processes, and participate in neural activities, neural nutrition, and the defense of CNS cells |
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central nervous system |
division of the nervous system consisting of the brain and spinal cord |
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peripheral nervous system |
division of the nervous system consisting of the cranial, spinal, and peripheral nerves that conduct impulses to and from the CNS and ganglia outside the CNS |
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stimuli |
environmental changes that neurons respond to |
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excitable |
cells that rapidly change their electrical potential in response to stimuli |
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membrane depolarization |
reversal of the ionic gradient of the plasma membrane |
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action potential/nerve impulse |
propagation of the depolarization across the entire plasma membrane |
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neural plate |
thickened ectoderm on the mid-dorsal side of the embryo, epithelial |
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neural tube |
when neural plate bends and grows together medially |
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neural crest |
large population of cells that will differentiate into cells of the PNS and other things |
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perikaryon/cell body |
cell body of the neuron, which contains the nucleus and most organelles |
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dendrites |
numerous elongated processes extending from the perikaryon and specialized to receive stimuli from other neurons at synapses, branch a lot |
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axon |
single long process that ends at a synapse, specialized to generate and conduct nerve impulses |
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multipolar |
one axon and two or more dendrites |
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bipolar |
one dendrite and one axon |
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unipolar/pseudounipolar |
one process that bifurcates near perikaryon, longer branch going to the PNS and other to the CNS |
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anaxonic |
many dendrites but no true axon- regulate electrical changes of adjacent neurons |
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sensory/afferent neurons |
receive stimuli from receptors throughout the body |
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motor/efferent neurons |
send impulses to effector organs |
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somatic |
nerves under voluntary control, innervate skeletal muscle |
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autonomic |
nerves under involuntary control, control activities of glands, cardiac muscle, and smooth muscle |
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interneurons |
99% of neurons, establish relationships among other neurons and form functional networks called circuits |
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gray matter |
part of CNS in spinal cord where neuronal perikarya concentrated |
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white matter |
part of CNS in spinal cord where axons concentrated |
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nerves |
bundles of axons in the PNS |
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neurofilaments |
intermediate filaments abundant in nerve cells |
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Nissl substance |
clumps of basophilic material that consist of concentrated RER and polysomes |
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dendritic spines |
short blunt structures projecting at points along dendrites that initially process synapses |
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axon hillock |
pyramid-shaped region of the perikaryon where axon originates |
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axolemma |
plasma membrane of an axon |
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axoplasm |
cytoplasm of the axon that contains mitochondria, microtubules, neurofilaments, and SER but no RER or polyribosomes |
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terminal arborization |
distal end of the axon that branches |
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collaterals |
branches of interneuron and some motor neuron axons |
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terminal bouton |
dilation of each branch of an axon that contacts another axon or non-nerve cell at a synapse |
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anterograde transport (neuron) |
from perikaryon to synaptic terminal through axon, mediated by kinesin |
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retrograde transport (neuron) |
from synaptic terminal to perikaryon, not as common, mediated by dyenin |
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voltage-gated Na+ and K+ channels |
produce waves of membrane depolarization by opening and closing to allow the ion content of the cell to change |
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resting potential |
little Na+ in cell compared to ECF and lots of K+ in cell |
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presynaptic cell |
cell that gives off an electric signal (nerve impulse) |
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postsynaptic cell |
cell affected by impulse/synapse- receives chemical signal |
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neurotransmitters |
small molecules that bind specific receptor proteins to open or close ion channels |
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synaptic vesicles |
vesicles that carry neurotransmitter released by exocytosis |
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postsynaptic cell membrane |
has receptors for transmitter and ion channels |
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excitatory synapses |
cause Na+ channels to open, resulting in depolarization |
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axosomatic |
synapse between axon and cell body |
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axodendritic |
synapse between axon and dendrite |
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axoaxonic |
synapse between axon and axon |
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glial cells |
cells that support neuronal survival and activities, develop from progenitor cells in the embryonic neural plate |
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neuropil |
cellular processes of neurons and glial cells that make up a fibrous intercellular network |
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oligodendrocytes |
glial cells that produce the myelin sheaths around axons, in white matter |
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astrocytes |
glial cells that have a large umber of radiating processes, are in the CNS |
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fibrous astrocytes |
astrocytes with few, long processes- in white matter |
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protoplasmic astrocytes |
many shorter, branched processes, in the gray matter |
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glial fibrillary acid protein |
protein that makes up intermediate fibers of astrocyte processes, common source of brain tumors |
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inhibitory synapse |
opens Cl- or other anion channels to hyperpolarize cell membrane |
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perivascular feet |
expanded ends of astrocyte processes that cover capillary endothelial cells |
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glial limiting membrane |
barrier layer that lines the meninges, formed from expanded processes of astrocytes |
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ependymal cells |
columnar or cuboidal glial cells that line the ventricles of the brain and the central canal of the spinal cord-move and absorb CSF |
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microglia |
small glial cells with short irregular processes that secrete immunoregulatory cytokines and act as the immune defense in the CNS |
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Schwann cells |
glial cells in PNS that myelinate axons and act as support |
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satellite cells of ganglia |
glial cells in the PNS that form an intimate covering layer over the large neuronal cell bodies in the ganglia of PNS |
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tract |
groups of myelinated axons in white matter |
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white matter |
myelinated axons and oligodendrocytes, very few neuronal bodies, some astrocytes and microglia |
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gray matter |
neuronal cell bodies, dendrites, unmyelinated parts of axons, where synapses occur |
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cerebellar cortex |
part of brain that coordinates muscular activity throughout the body, and has three layers: outer molecular, Purkinje, inner granular |
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cerebral cortex |
composed of six layers, integrates sensory info and initiates voluntary motor responses |
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pyramidal neurons |
efferent neurons that comprise a layer in the cerebral cortex |
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molecular layer |
outer layer of cerebellar cortex |
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Purkinje cells |
large neurons that compose the central layer of the cerebellar cortex |
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granule layer |
inner layer of the cerebellar cortex |
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central canal |
opening in the spinal cord that develops from the lumen of the embryonic neural tube, continuous with ventricles, contains CSF, lined with ependymal cells |
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anterior horns |
formed from gray matter, motor neurons |
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posterior horns |
gray matter, sensory fibers |
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meninges |
membranes of connective tissue between bones and nervous tissue: dura mater, arachnoid mater, pia mater |
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dura mater |
thick external mater, dense, fibroelastic CT continuous with the periosteum of the skull |
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subdural space |
space that separates the arachnoid mater from the dura mater |
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arachnoid mater |
middle mater with 2 layers: sheet of CT and a system of loosely arranged trabeculae composed of collagen and fibroblasts |
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subarachnoid space |
cavity surrounding trabeculae filled with CSF that communicates with ventricles of the brain |
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arachnoid villi |
CSF filled protrusions of the arachnoid into the venous sinuses that are covered by vascular endothelial cells |
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pia mater |
innermost mater that consists of flattened, mesenchymally derived cells |
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perivascular spaces |
spaces covered by pia mater that blood vessels penetrate |
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blood-brain barrier |
functional barrier that allows tight control over what passes from blood to CNS tissue, consists of capillary endothelium sealed with occluding junctions |
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limiting layer of perivascular astrocytic feet |
completely envelopes the basal lamina of the capillaries in CNS regions- regulates passage of ions and molecules from blood to brain |
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choroid plexus |
highly specialized tissue with elaborate folds and many villi in the ventricles that removes water from blood and makes CSF |
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CSF |
clear fluid, contains Na+, K+ and Cl-, and a few lymphocytes- fills the ventricles and subarachnoid space to provide ions for neuronal activity and avoid physical shocks |
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chromatolysis |
onset of regeneration: perikaryon swells slightly, Nissl substance diminishes, nucleus peripheral, etc. |
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neurotrophins |
growth factors produced by neurons and glial cells |
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autonomic ganglia |
control activity of smooth muscle, small bulbous dilations in autonomic nerves, layer of satellite cells |
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intramural ganglia |
ganglia in the wall of the digestive tract |
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sensory ganglia |
ganglia that receive afferent impulses, have large neuronal bodies with satellite cells and a CT capsule |
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epineurium |
dense, irregular fibrous coat of entire nerves |
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perineurium |
CT layer around nerve fascicles that contain flat fibrocytes joined by tight junctions |
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fascicles |
bundles of axons with Schwann cells and endoneurium |
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endoneurium |
reticular fibers, scattered fibroblasts, and capillaries that surround one Schwann cell |
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nerve |
bundle of nerve fibers |
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unmyelinated fibers |
axons enveloped in a simple fold of Schwann cell |
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internodal segment |
length of an axon ensheathed by one Schwann cell |
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nerve fibers |
analagous to tracts in CNS, axons enclosed in sheaths of Schwann cells |
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myelin sheath |
layers of Schwann cell membrane fused together around an axon |
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major dense lines |
fused, protein-rich cytoplasmic surfaces of the Schwann cell membrane |
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myelin cleft |
separations in cytoplasmic surfaces to allow cytoplasm to move |
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nodes of Ranvier/nodal gaps |
gaps between adjacent Schwann cells on a single axon |
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cardiovascular system |
consists of heart, arteries, veins, arterioles, venules, and capillaries- circulates blood through body |
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arteries |
vessels that carry blood to the tissues from the heart |
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capillaries |
the smallest vessels that are the sites of O2, CO2, nutrient, and waste exchange between blood and tissues |
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microvasculature |
network of capillaries, arterioles, and venules that anastomose |
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veins |
vessels that carry blood from tissue to heart |
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pulmonary circulation |
division of the circulatory system where blood is oxygenated in the lungs |
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systemic circulation |
division of the circulatory system where blood brings nutrients and removes waste in tissues throughout the body |
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lymphatic vascular system |
system that returns fluid from tissue spaces back to the heart |
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lymphatic capillaries |
thin-walled, closed-ended tubules carrying lymph |
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endothelium |
single layer of squamous epithelium that lines all components of the blood and lymphatic systems- selectively permeable |
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ventricles |
chambers of heart that pump blood to systemic and pulmonary circulation |
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atria |
chambers of the heart that receive blood from the body and pulmonary veins |
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endocardium |
inner layer of heart wall- consists of thin endothelial layer with CT, a middle myoelastic layer of smooth muscle and connective tissue, and a deep layer of connective tissue |
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subendocardial layer |
deep CT layer of endocardium that merges with the myocardium |
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myocardium |
thickest layer of heart wall that consists of cardiac muscle surrounding heart, thicker around ventricles |
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epicardium |
simple squamous mesothelium with loose CT, same as visceral layer of the pericardium |
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visceral layer of pericardium |
membrane surrounding heart, known as epicardium |
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parietal layer of pericardium |
outer layer of membrane surrounding heart |
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cardiac skeleton |
dense irregular fibrous connective tissue that anchors and supports heart valves, provides points for insertion of cardiac muscle, and helps coordinates heartbeats |
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conducting system of the heart/subendocardial conducting network |
generates and propagates waves of depolarization that go to myocardium- heartbeat |
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sinoatrial node |
node in right atria of specialized cardiac muscle cells that creates initial impulse |
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atrioventricular node |
in floor of right atrium, spreads depolarization |
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Atrioventricular bundle |
takes impulse from AV node to subendocardial conducting network |
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Purkinje fibers |
myofibers of subendocardial conducting network, pale staining, mingle with contractile muscle fibers, and cause contraction |
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vasa vasorum |
blood vessels within the tunica adventitia in larger vessels |
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tunica adventitia |
outer layer of vessels made up of collagen I and elastic fibers |
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tunica media |
middle layer of vessel walls made up of smooth muscles, controls blood pressure, has elastic, reticular fibers, and proteoglycans |
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internal elastic lamina |
limiting layer of tunica intima made of elastic |
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tunica intima |
endothelium and loose CT subendothelial layer- inner layer of vascular wall |
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angiopoietins |
growth factors that stimulate endothelial cells to attract smooth muscle fibers |
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angiogenesis |
process of sprouting capillaries and vessels from existing ones |
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vasculogenesis |
creation of vasculature from embryonic mesenchyme |
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endothelium |
specialized epithelium that acts as a semipermeable barrier between blood plasma and interstitial tissue fluid |
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nonthrombogenic surface |
endothelium- surface where blood will not clot |
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P-selectin |
secreted to activate white blood cells in time of injury |
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interleukins |
secreted by endothelial cells, affect the activity of local white blood cells during inflammation |
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elastic/conducting arteries |
aorta, pulmonary artery, and large branches |
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systole |
ventricular contraction, causes blood to move forcefully through arteries |
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diastole |
ventricular relaxation, elastin passively rebounds in elastic arteries |
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carotid sinuses |
slight dilations of the internal carotid arteries- act as baroreceptors |
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baroreceptors |
monitor arterial blood pressure |
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chemoreceptors |
monitor blood levels of CO2 and O2 and hydrogen ion concentrations |
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carotid bodies and aortic bodies |
sites for chemoreceptors in the internal carotid arteries and the aortic arch |
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paraganglia |
carotid bodies and aortic bodies that are parts of the autonomic nervous system and have rich capillary networks |
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glomus (type I) cells |
large, neural crest-derived cells surrounding capillaries around carotid and aortic bodies- filled with dense-core vesicles containing neurotransmitters that regulate blood chemical levels |
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thoracic duct |
lymphatic trunk that enters the cardiovascular system between the left subclavian vein and the left internal jugular vein |
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right lymphatic duct |
lymphatic trunk that enters the cardiovascular system between the right subclavian vein and right internal jugular vein |
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lymphatic vessels |
similar structure to veins except with thinner walls and no distinct separation of tunics and more internal valves, often dilated with lymph, bring lymph back from lymphatic capillaries to lymphatic ducts |
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lymphatic capillaries |
closed-ended vessels with a single layer of endothelial cells on an incomplete basal lamina that collect lymph in tissues |
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lymph |
excess interstitial fluid in tissue spaces that is usually rich in light staining proteins |
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large veins |
big venous trunks with a well-developed intima, thin media with alternating muscle and CT layers, and thick adventitia with longitudinal muscle cell bundles; run with elastic arteries |
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small and medium veins |
veins that correspond to muscular arteries, have diameters of 10mm or less, have a thin subendothelial layer, well-developed adventitia, and a media with muscle cell bundles and reticular and elastic fibers |
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veins |
vessels that carry blood back to heart, have valves to prevent backflow |
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muscular venules |
venules with a tunica media consisting of 2-3 smooth muscle layers, large lumen and thin walls |
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collecting venules |
convergence of postcapillary venules, have more contractile cells than the former |
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postcapillary venules |
structurally similar to capillaries, have pericytes, slightly larger, primary site where white blood cells adhere to endothelium and leave circulation to treat infection/injury |
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pericytes |
mesenchymal cells with long cytoplasmic processes that partly surround the endothelial layer of capillaries and postcapillary venules; make their own basal lamina and have a contractile function |
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discontinuous capillaries/sinusoids |
permit maximal exchange of macromolecules, have endothelial cells with perforations, gaps between cells and a discontinuous basal lamina, have a larger diameter, found in liver, spleen, bone marrow, and some endocrine organs |
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fenestrated capillaries |
sieve-like structure that allows more molecular exchange- endothelial cells have perforations sometimes covered by proteoglycan diaphragms, have a continuous basal lamina, found in kidneys, intestine, choroid plexus, and endocrine glands |
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continuous capillaries |
many tight occluding junctions, slightly overlapping endothelial cells; most common type of capillary; found in muscle, CT, lungs, exocrine glands, and nervous tissue |
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precapillary sphincters |
muscle fibers that contract or relax rhythmically to control entry of blood into capillaries |
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thoroughfare channels |
channels that connect metarterioles to postcapillary venules and bypass capillaries |
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metarterioles |
terminal arteriole branches that supply capillary beds |
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capillary beds |
groups of capillaries around organs, size and structure depends on metabolic activity of organ |
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capillaries |
small vessels that regulate metabolic exchange between blood and surrounding tissues |
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portal system |
system in which a portal vein connects two capillary beds- transport of hormones and nutrients |
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arteriovenous shunts |
a way to bypass capillary networks, media and adventitia thicker |
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microvasculature |
where exchanges between blood and tissue fluid occur |
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arterioles |
smallest artery branches- 1-2 smooth muscle layers, beginning of microvasculature |