composed of uninucleate cylinders
diameter of 10–20 µm and lengths of 50–100 µm
joined together at intercalalted discs
tight junctions
gap junctions
cross-striated
cells are branched
no neuromuscular junctions
action potentials generated within the heart
transmitted from cell to cell through the gap junctions
motor neurons of autonomic modulate intrinsic rate and strength of contraction
time to peak contraction about 150 ms
mechanism essentially the same as in skeletal
T-tubules invaginate at level of Z-line
sarcoplasmic reticulum relatively poorly developed
prolongation of the action potential (about 200 msec)
very dependent on cellular respiration for ATP synthesis
refractory period longer than contraction cycle
cardiac tetanus is impossible
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[ Anatomy & Physiology 1 syllabus ] [ Page created 19 June 2007 ] [ Questions about this lecture? E-mail me ] |