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71 Cards in this Set
- Front
- Back
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Endomysium surrounds? And is composed of?
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Surrounds: individual muscle cells, Composed of: reticular fibers and an external lamina.
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Perimysium surrounds?
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surrounds: fascicles (bundles of muscle fibers)
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Epimysium surrounds?
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surrounds an entire muscle.
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What is a big difference between white and red muscle fibers?
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white muscle fibers are poor in myoglobin whereas red muscle fibers are rich in myoglobin.
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F-actin is a polymer of?
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G-actin monomers arranged in a double helix.
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Thin filament is composed of?
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F-actin, tropomyosin, troponin, and associated proteins.
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What does troponin concist of?
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3 globular subunits: TnT, TnC, TnI.
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What does TnT do and form?
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Binds to tropomyosin. Forms tail of molecule.
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What does TnC do?
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Binds to calcium.
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What does TnI do?
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Binds to actin, inhibits binding of actin and myosin.
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In the absence of calcium, tropomyosin-troponin complex does what?
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blocks the binding of myosin to actin.
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Binding of calcium to TnC does what?
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allows contraction to proceed.
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Myosin consist of?
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2 heavy chains, 2 pairs of light chains
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What enables myosins binding to actin?
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ATP hydrolysis.
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What does the "heavy chains" consist of?
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long rod-like "tail" and a globular "head" functioning in contractions, it has actin binding sites.
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Thick filament contains?
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around 250 myosin molecules arranged in antiparallel fashing and 3 associated proteins: myomesin, titin, and C protein
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What are the three types of myofilaments?
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Thick, Thin and elastic filaments.
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longitudinally oriented cytoplasmic components of skeletal and cardiac muscle fibres, which are the loci of force-generation when the muscle is activated
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myofibril
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What is a Z disc and what important protein does it contain?
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Borders sacromere, contain alpha-actinin.
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What is a A band?
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Space which contains thick filaments and partially thin filaments.
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What is a H band?
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middle part of A band which contains only thick filaments
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What is a M line and what activity it has?
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in the center of H band, anchors two adjacent myosin myofilaments together, has activity of creatine kinase.
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What is a I band?
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area in two adjacent sacromere that only contains actin myofilaments
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Myosin II function?
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Major protein of thick filament; its interaction with actin hydrolyzes ATP and produces contraction.
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Myomesin function?
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Cross-links thick filaments that are next to each other at M line.
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Titin function?
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forms an elastic lattice that anchors thick filaments to Z disks
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C protein function?
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binds to thick filaments at the M line.
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G actin function?
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Polymerizes to form thin filaments of F-actin; interaction of G-actin with myosin II assists in hydrolyzing ATP, resulting in contraction.
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Tropomyosin function?
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occupies grooves of the thin filaments
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Troponin function?
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Binds calcium, Binds to tropomyosin, Binds to actin, thus inhibiting actinmyosin interaction.
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alpha-actinin function?
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Anchors plus ends of thin filaments to Z disk
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Nebulin function?
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Z disk protein that may assist alpha-actinin to anchor thin filaments to Z disk.
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Cap Z function?
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Forms part of the Z disk and caps the plus end of the thin filament.
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Tropomodulin function?
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Caps the minus end of the thin filament.
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What anchors Z disks to each others?
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Desmin
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At the cell periphery Z disks are anchored to the sarcolemma by ___, which contains elements called ___. (complete sentence)
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vinculin, costameres
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Titin binds in the __ line to thee protein ___
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M, myomesin
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What is the function of creatin kinase?
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an enzyme, that recovers ATP from phosphocreatine and ADP.
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What links desmin filaments to each other?
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Plectin.
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Heat shock proteins, protects desmin from stress-induced damage
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alpha- and beta-crystallin.
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structure associated with the sarcoplasmic reticulum, made by the invaginations of the sarcolemma.
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T tubules.
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Specialized complexes consisting of a narrow central T tubule flanked on each side by terminal cisternae of SER
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Triads.
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Where are triads located?
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at the A-I junction in skeletal muscle cells.
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what is the function of triads?
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they help in providing unifrom contraction.
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what is the neurotransmitter of muscle cells?
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Acetylcholine
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What effect does [ACh] have on the sarcolemma?
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It binds to receptors on sarcolemma, makes sarcolemma more permeable to sodium ions, membrane gets depolarized and signal is passed using T tubules, this stimulate SER, sequestering of calcium ions to sarcoplasm commences and contraction starts.
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how does the restoring of the cytosolic Ca2+ concentration work after a muscle contraction and how long does it take?
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Ca2+ ATPases in the SER membrane, pump Ca2+ ions from the cytosol back into the SER, whole process takes about 30 milliseconds.
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Difference between T tubules of striated muscle cells and cardiac?
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they are 2,5 times larger in cardiac, and from dyads.
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small regenerative cell, which have one nucleus, located in shallow depressions on the muscle cell's surface, sharing the muscle fibers external lamina called?
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satellite cells.
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during muscle contraction what happens to the I band?
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becomes narrower
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during muscle contraction what happens to the H band?
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extinguished
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during muscle contraction what happens to the Z disks?
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they move closer to each others.
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Light meromyosin consits of?
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a rod-like tail composed of most of the two rod-like polypeptide chains wrapped around each other.
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Heavy meromyosin consists of?
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the two globular heads with the attendant short proximal portions of the two rod-like polypeptide chains wrapped around each other,
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The heavy chains of myosin II is cleaved by?
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trypsin
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function of muscle spindles?
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monitor the length and the changes in length of the muscle.
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Golgi tendon organs function?
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monitors the intensity of muscle contraction.
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Cardiac muscle differs from skeletal and smooth muscles in that it posses an __ __ as well as the ability to __ __ (complete sentence)
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inherent rhythmicity, contract spontaneously
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Cardia muscle cells form higly specialized end to end junctions referred to as __ __
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intercalated disks.
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What does calcium bind to in smooth muscle?
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calmodulin
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In smooth muscle what is equivalent to the T- Tubule system in striated muscle?
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Caveolae
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3 specializations of intercalated disk?(cardiac muscle cells)
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* Fasciae adherents (analgous to zonula adherents) * Desmosomes (macula adherents) * Gap junctions
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Which intermediate filaments are present?(smooth muscle cells)
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Vascular smooth muscle cells = vimentin & desmin Avascular = only desmin
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In smooth muscle what is equivalent to the z-disk system in striated muscle?
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Dens bodies/focal densities
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1. What kind of intermediate filaments can be found in smooth
muscle cells? 1-vimentin, 2-desmin, 3-keratin, 4-tonofilaments, 5-neurofilaments, 6-myosin, 7-α-actinin, 8-laminin A. 1,2,3,4,5,6,7,8 B. Only 1 and 2 are correct C. 1,2,6,7 D. 3,4,7 E. 5,8 |
B
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2. Which of these can be an energy source for skeletal muscle
contractions? 1-ATP, 2-creatine phosphate, 3-phosphogen energy system, 4- glycolysis, 5-lipid droplets, 6-glycogen A. 1,2,3,4,5,6 B. Only 1 C. Only 1,2 D. Only 3,4 E. Only 1,3,4 |
A
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3. Which of these is related to the white muscle fibers?
1-rich vascular supply, 2-larger nerve fibers, 3-slow but repetitive, 4-weaker contraction, 5-numerous mitochondria, 6-rich in myoglobin, 7-poor in adenosine triphosphatase A. all are correct B. all are correct except 2 C. 1,2,3,4,7 D. only 2 E. 5,6 |
D
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4. What are the sources of calcium ions for cardiac muscle
contractions? 1-SER, 2-sarcolemma, 3-negatively charged external lamina, 4-fast sodium channels, 5-slow sodium channels, 6-exteracellular space A. All of these B. All of these except 4 C. Only 1 D. Only 1,5,6 E. Only 1,2 |
B
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5. Which of the following sentences concerning nebulin is TRUE?
A. It anchors thin filaments to Z discs. B. It binds calcium ions. C. It caps the minus end of the thin filament. D. It cross-links thin filaments. E. It occupies grooves of thin filaments. |
A
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6. Which from the following proteins bind to thin filaments in sarcomere?
1-myomesin, 2-titin, 3-C protein, 4-tropomyosin, 5-troponin, 6-α-actinin, 7-nebulin, 8-Cap Z, 9-tropomodulin A. all of these B. 1,2,3,8 C. 4,5,6,7,9 D. 2,3,4,8,9 E 5 6 7 9 |
C
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inhibits the ATPase activity of myosin in smooth muscle, and binds to calmodulin
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Caldesmon
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