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31 Cards in this Set
- Front
- Back
What are muscles made of? |
composed of muscle cells, myofibres, or muscle fibers that specialize in contraction |
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What are the 2 classification of muscles based on appearance of contractile cells? |
- striated muscle - smooth muscle |
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What are the 2 groups striated muscles divide into? |
1. Cardiac muscle: involuntary muscle in walls of heart 2. Skeletal muscle: voluntary muscle |
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What are the 3 bundles of tissue sheath of the skeletal muscle? |
1. Epimysium: dense connective tissue covering entire muscle 2. Perimysium: surrounds bundles of fascicles of muscle cells 3. Endomysium: delicate layer of reticular fibers and ECM surrounding each muscle cell |
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Describe the muscle cell in skeletal muscle |
- post mitotic multinucleated synctium - nuclei lie below sarcolemma - sarcolemma contains satellite cells (help muscle regeneration) - where you find site of a triad (2 lateral sacs of sarcoplasmic reticulum and central T tubule) |
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Describe the myofibrils of the skeletal muscle fiber (hint: sarcomeres) |
- myofibrils contain sarcosomes (type of mitochondria) - 2 filaments: thin and thick filaments - Thin filament: contains actin, form I band (light) - Thick filament: contains myosin, form A band (dark) - I band bisected by Z line, A band bisected by H band |
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What is a sarcomere? |
the basic contractile unit of skeletal muscle and is portion of myofibril between 2 adjacent Z lines |
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What are the 3 parts of muscle contraction? |
1. length of thick&thin filament does NOT change during contraction 2. length of sarcomere decreases / size of H band and I band decreases 3. force of contraction generated by process that moves one filament past the adjacent filament |
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What are satellite cells? |
- cells that are significant in muscle maintenance, repair, and regeneration - basis of stem cell therapy in muscle injuries and degenerative diseases - mitotically quiet in adults, but can come back in response to stress/trauma |
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Describe the cardiac muscle cells |
- branched cylinders with centrally located nucleus - organization of contractile proteins (same as ones found in skeletal muscle) - have T tubules @ level of Z disc, sarcoplasmic reticulum not extensive, have Diads, and mitochondria are abundant |
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How are cardiocytes joined? |
- cardiocytes are cardiac muscle cells - joined end to end by intercalated discs |
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What does cardiac muscle exhibit that is unique to it? |
- a spontaneous rhythmic contraction (heart beat) - initiated, regulated, and coordinated by cardiac conduction cells - cells organized into Purkinje fibers |
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What is a myocardial infarction? |
- loss of blood supply (ischemia) to the myocardium - caused by obstruction of atherosclerotic coronary artery - damages cardiocytes if ischemia occurs for more than 20 minutes |
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What is reperfusion? |
- it is the process of cardiac cell viability being restored - occurs after myocardial infarction (ischemia) occurs for less than 20 minutes |
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Where is smooth muscle found? |
located in walls of gut, bile duct, ureters, urinary bladder, respiratory tract, uterus, and blood vessels |
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How is smooth muscle different from cardiac muscle? |
- spindle shaped with tapering cells with a central nucleus - perinuclear cytoplasm contains a lattice work of thick myosin filament, thin actin filaments, and desmin&vimentin filaments (attached to dense bodies) - invaginations of plasma membrane called caveolae act as T tubule system - basal lamina surrounds each muscle cell - transmits forces produced by cells |
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What is the specialization of smooth muscle? |
it is specialized for slow and prolonged contraction |
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What are dense bodies? |
It is where actin and myosin filaments attach to. The attachment to the dense body is what determines cell shortening. |
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How does smooth muscle renew itself? |
- smooth muscles divide to maintain or increase their number - smooth muscle in uterus proliferates during pregnancy |
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What is included in the central nervous system? |
brain and spinal cord |
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What is included in the peripheral nervous system? |
peripheral ganglia, nerves, and nerve endings |
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What does the nervous system control? |
It controls and integrates the functional activities of organs and organ systems. It also enables the body to respond to continuous changes. |
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Describe the composition of nerve tissue |
- consists of neurons and supportingg cells (neuroglial cells) - neurons are basic unit of structure&function - 3 main categories: sensory neurons, motor neurons, and interneurons |
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What are the 3 types of neurons? |
1. multipolar neurons 2. bipolar neurons 3. pseudounipolar neurons |
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What are synapses? |
- specialized junctions between neurons that help in transmission of impulses - how neurons communicated with each other and effector cells |
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What are examples of peripheral neuroglia? |
- schwann cells - satellite cells - cells in motor end place - retina - certain ganglia located in alimentary canal |
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What are the 4 types of central neuroglia? |
1. astrocytes 2. oligodendrocytes 3. microglia 4. ependymal cells |
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What is a peripheral nerve? |
a bundle of nerve fibers held together by connective tissue |
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What is each nerve composed of? (peripheral nerve) |
- fascicles which are nerve fiber bundles - enclosed by epineurium, perineurium, and endoneurium - endoneurium composed of callagenous&reticular fibers with fibroblasts¯ophages |
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Why can't nerve fibers regenerate from injury in the CNS? |
Because the glial cells in the CNS are unable to phagocytose quickly enough, so it leaves a scar. |
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What is reactive gliosis? |
- it is scar formation in the CNS - astrocytes near lesion are activated and form a scar (reactive gliosis) and becomes a permanent scar (plaque) - leads to no recovery or very minimal recovery |