Question

Assertion: Intercalated discs are important regions of cardiac muscles cells.
Reason: Intercalated discs function as boosters for muscle contraction waves.
A. Both Assertion and Reason are correct and Reason is the correct explanation for assertion.
B. Both assertion and Reason are correct but Reason is not the correct explanation for assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and reason are incorrect.

Answer 1

Hint: Intercalated discs are part of the cardiac muscle which are identifying. Cardiac muscles consist of cardiomyocytes, which are connected by intercalated discs and work in a single functional organ or syncytium. Basically, intercalated discs support synchronized contraction of cardiac tissue.

Complete answer:
Intercalated discs is the junction formed in between muscle cells which are dense in nature where they formed. These are the specialized regions of cell membranes, these act as a booster for contraction of waves, when cardiac muscles generate their own excitation and maintain rhythmicity. They are present at the z line of sarcomere and easily distinguished by observing in longitudinal sections of tissue.

Intercalated discs are formed by three types of cell junction and their name as fascia adherens, desmosomes and gap junctions, and such junctions are anchoring sites of actin, stop separation during contraction by binding filament and allow action potential respectively.

The intercalated discs are formed by most of the missed type adherens junction, which are termed as composite junction. They are formed by desmosomal and fascia adherens protein. The epithelial adherens junction and desmosomes are different from cardiomyocyte junction.

Intercalated discs possess gap junctions which are protein lined tunnels which allow direct transmission of depolarizing current from cell to cell, throughout the heart that make cells contract in unison.

Hence, the correct answer is option (A).

Note: Intercalated discs are only found in cardiac muscles and they are different from other muscles, they are branched which allow transmission of electrical impulse and connection between cells, while skeletal muscle fibers are unbranched and lack the intercalated disc and are not electrically connected.