Question

What are the functions of desmosomes and gap junctions in cardiac muscle cells?

Answer 1

Both desmosomes and gap junctions are present in the intercalated discs present in the cardiac muscle tissues. Desmosomes also called the macula adherens play a major role during contraction whereas gap junction helps in spreading action potential in cardiac cells.

Complete answer:
Cardiac muscle tissue is only found in the heart. Coordinated contractions of these cardiac muscles pump blood into the vessels of the circulatory system. They possess many mitochondria and myoglobin and are highly branched interconnected to each other at their ends by intercalated discs.

Intercalated discs are the part of the sarcolemma that contains two structures that are important for muscle contraction : gap junctions and desmosomes.

GAP JUNCTION- They form channels between adjacent cardiac muscle fibres that allow the depolarizing current produced by cations to flow from one cardiac muscle allowing quick transmission of action potential and coordinate in the contraction of the heart. It forms up a network of electrically connected cardiac muscle cells called syncytium.
FUNCTION-
1. Facilitate electrical communication so that waves of depolarisation spread rapidly in the heart.
2. Provide direct contact between the cardiac cells.

DESMOSOME- It is a cell structure that anchors the ends of cardiac muscle fibres together. It is done so, so that they anchor the ends of cardiac muscle fibres together so that the cells do not pull apart during the stressful conditions.
FUNCTION
1. Site of strong adhesion
2. Helps to keep the muscle cells connected.

Note: Contraction of the heat or the heartbeat is controlled by specialized cardiac muscle cells called as pacemaker cells that helps in controlling the heart rate. Although cardiac muscle cannot be consciously controlled, these pacemaker cells respond to ANS too slow or speed down the heart rate.