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10 Cards in this Set
- Front
- Back
Cardiac Muscle
General |
striated
myocytes are SEPARATE cells unlike skeletal fibers beat in unison, functional syncytium not structural syncytium Autonomic NS regulates(NOT generates) cardiac rhythm |
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Cardiac Muscle
Structure: light microscopy ie how to ID |
myocytes branch, cells are attached at intercalated discs
have more capillaries myocytes are mono- or bi-nucleate and are centrally located cross section - fibers are more uniform than smooth muscle but still different sizes and shapes |
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Cardiac Muscle
Structure: electron microscopy |
- nuclear region also contains organelles
- intercalated discs( where the last Z-line in the cell would normally be) - LOTS of mito - Sarcomeres (contractile units similar to skeletal) - SR and T tubules |
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SR and T tubules in cardiac muscle
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less extensive, sometimes they dont even form a triad, one t-tubule attaches to SR instead of two SR's (forming a diad)
what does this mean for Ca? ?? pg 316 |
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intercalated discs
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step like junctions(not all myofibrils in myocytes are equally long)
- gap junctions on longitudinal portions - fasciae adherens, similar to zonula adherens except not belt-like (THIN FILAMENTS) - maculea adherens (desmosomes)punctuate the fasciae adherens on the transverse side (INTERM FILAMENTS) |
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Cardiac Muscle
Impulse conduction system composed of? |
- modified muscle cells , NOT neurons
- SA node - AV node - AV bundle (bundle of HIS) - right and left bundle branches, cells gradually become purkinje fibers |
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Nodal Fibers
what are they bigger or smaller than myocytes? attachment? membrane potentials conduction from where to where |
SA AV nodes:
smaller in diam than myocytes attached via gap junctions oscillating membrane potentials conduction goes from SA to AV |
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AV node
connections |
AV electrically connected to conducting fibers (Purkinje) in the AV bundle(branches of bundle of HIS)
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Purkinje fibers
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larger than myocytes
more glycogen(paler) gap junctions with eachother branching bundles run under endocardium toward heart apex, then bend back and make gap junctions with ventricular myocytes |
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smooth muscle
location function |
walls of organs that are tubular, or sac shaped(uterus/bladder)
slow contraction, low ATP consumption most recently evolved tissue |