How does the structure of cardiac myocytes and intercalated discs allow the function of cardiac muscle tissue and the heart?

The intercalated discs of the heart muscle have gap junctions that allow electrical impulses to pass from one myocyte to the next, so they contract in unison as a syncytium, in a phenomenon called electrical coupling. Intercalated disks also have desmosomes, that provide structural support and prevent the myocytes from tearing away from one another during the stresses of contraction.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

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