Unformatted text preview: but also
allowing ions to ﬂow
through gap junction. Intercalated discs are irregular and often difficult to distinguish with the LM.
(Do not confuse intercalated discs with Z discs– two very different things.) Intercalated discs of cardiac muscle Fig. 10-17
These are sites of gap junctions, desmosomes, and fascia
adherens (for intercellular communication & strong adhesion.) Smooth muscle
DUCTS -- GI tract, uterus, vessels. Cells/fibers are much smaller,
tapered in shape, with central nuclei,
and remain as individual cells linked by
many gap junctions.
Much SPARSER conc. of thick/thin
ﬁlaments and less organized -- no
striations. Functionally theyre all merged… look like looong ﬁbroblasts -- elongated.
single nucleus in middle of cell. looks like
all cells highly linked together by gap jxns. Smooth m. sarcoplasm is much less
well-organized (and show no striations)
and contracts with much less force.
The cells/fibers can still divide, so
repair or r...
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- Spring '14