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19 Cards in this Set
- Front
- Back
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Describe thin filament component of myofilaments
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made of fibrous actin (F actin)
F actin is a polymer formed from globular (G actin) actin molecules. 6-8 nm in diameter, 1.0 micrometer long |
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Describe the physical characteristics of thick filament component of myofilaments
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- 15 nm diameter, 1.5 micrometer long
each consists of 200-300 myosin II molecules organized in a staggered array |
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It looks just like skeletal muscle under a microscope but plays a role only in soft tissues.
What is it essential for? |
Visceral striated muscle.
Found in soft tissues: Tongue, pharynx, lumbar part of diaphragm. Essential for breathing, speech, swallowing. |
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What is the main morphological difference between skeletal muscle cells and cardiac muscle cells?
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Size, shape, and organization relative to each other.
Cardiac muscle has intercalated discs and the fibers have variable length. Larger T tubules. Cell nuclei are located in the center of the fiber usually. large mitochondria are densely packed between the myofibrils. |
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What parts of the body are smooth muscles restricted to?
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viscera, vascular system, arrector pili muscles of skin, intrinsic muscles of eye.
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What in the hell is a 'syncytium' ????
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A syncytium (/sɪnˈsaɪtiəm/; plural syncytia; from Greek: σύν (syn) = "together" + κύτος (kytos) = "box, i.e. cell") is a multinucleate cell which can result from multiple cell fusions of uninuclear cells (i.e. cells with a single nucleus), in contrast to a coenocyte which can result from multiple nuclear divisions without accompanying cytokinesis.[1] A classic example of a syncytium is the formation of skeletal muscle. The term may also refer to cells that are interconnected by specialized membrane with gap junctions, as seen in the heart muscle cells and certain smooth muscle cells, which are synchronized electrically in an action potential. (Thanks Wikipedia)
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WHERE DO THE LITTLE LINES POINT???
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What is the endomysium yo?
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Delicate layer of reticular fibers surrounding single muscle fibers.
Endo_______ |
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Perimysium?
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Surrounds a group of muscle fibers to form a fascicle/bundle.
Peri___________ |
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epimysium?
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surrounds a collection of fascicles/bundles.
Epi___________ The Endomysium, Perimysium, and Epimysium all have blood vessels and nerve fibers of increasing size in em. |
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why do some types of muscle fibers stain darker with NADH-TR?
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more mitochondrial oxidative enzymes = more reactions with the stain.
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draw a quick sketch of a sarcomere resting and then contracted. include the I, A and H zones and the Z and M lines.
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What are terminal cisterna good for?
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store reservoirs of Ca2+
It is a more regular ring like channel formed by the SR. |
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AChE inhibitors are a very painful class of toxins, why?
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Without AChE, ACh would not be broken down and your muscles would not be able to relax until your guts spilled out. (at least this is what my 10th grade anatomy teacher told me)
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When voltage gated Na+ channels open, Voltage sensor proteins in the T tutbules change their conformation. What happens at the muscle cell triads next?
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The T tubules are in close contact with the SR. Gated Calcium release channels are activated and Ca2+ is released from SR into sarcoplasm.
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Muscle Spindle is....
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a specialized stretch receptor in muscle.
consists of Spindle Cells and Neuron Terminals. |
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What are secondary myotubes, what do they originate from?
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They are formed in the innervated zone of developing muscle where myotubes have direct contact with nerve terminals.
They come from late myoblasts. They are smaller diamter than primary myotubes. They have more widely spaced nuclei and more myofilaments. |
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What if your satellite cells all disappeared?
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Muscle would have a harder time regenerating. Myogenic cells may be recruited from the bone marrow.
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What are Dense Bodies? (in smooth muscles)
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They have a variety of attachment plaque protiens (like alpha actinin) that anchors thin and intermediate filaments to the sarcolemma in order to transmit force and keep the 'cat from ripping the bag'. (analogous to Z lines in striated muscles) in EM, they may also appear linearly sometimes.
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