Intercalated disc is composed of: 1. Cadherins 2. Desmosomes 3. Gap junctions 4. Tight junctions

INI-CET EXAM -2026

Applied Anatomy

Easy

Appeared in: INI-CET EXAM -2026

Explanation

Intercalated discs are specialized junctions unique to cardiac muscle that mechanically and electrically couple adjacent cells.
They contain adherens junctions (which use cadherins) and desmosomes to provide strong mechanical adhesion, preventing cells from separating during forceful heart contractions.
They also contain gap junctions, which are protein channels that allow electrical impulses (action potentials) to spread rapidly from one cell to the next.
This combination of strong adhesion and rapid electrical communication allows the entire heart muscle to contract in a coordinated and synchronized manner, a state known as a functional syncytium.

Option B: This option is incorrect because it includes tight junctions (4), which are not a component of intercalated discs. Tight junctions form impermeable seals, which would hinder the function of cardiac muscle.
Option C: This option is incorrect because it includes tight junctions (4) and excludes desmosomes (2). Desmosomes are essential for providing the mechanical strength required to withstand the stress of heart contractions.
Option D: This option is incorrect because it includes tight junctions (4). While the other three components are correct, the inclusion of tight junctions makes the entire option invalid.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Composition and function of intercalated discs in cardiac muscle tissue as background academic context rather than a clinical decision trigger.
The structure of intercalated discs allows the heart to act as a 'functional syncytium,' meaning that although it is composed of individual cells, it behaves as a single, coordinated unit.
Defects in the proteins of these junctions can lead to serious heart conditions. For example, mutations in desmosome proteins are a known cause of Arrhythmogenic Cardiomyopathy (ACM), a disease that can lead to life-threatening arrhythmias and heart failure.
What if? If gap junctions were absent or non-functional, the electrical signal for contraction could not pass efficiently between cells. This would lead to uncoordinated contractions (fibrillation) instead of a unified heartbeat, which is a life-threatening emergency.

How to Approach the Question

First, identify the core of the question, which is asking for the structural components of an intercalated disc.
Recall that intercalated discs are unique to cardiac muscle and serve two main purposes: strong adhesion and rapid electrical communication.
Evaluate each of the four listed components based on these functions.
Cadherins and Desmosomes are adhesion molecules, crucial for mechanical strength. Gap junctions are channels for communication. These fit the required functions.
Tight junctions create seals to prevent leakage, a function not required for cardiac muscle contraction and which would impede electrical coupling. Therefore, eliminate tight junctions.
Finally, choose the option that includes all the correct components (1, 2, and 3) and excludes the incorrect one (4).

Concept Tested & Keywords

Concept Tested: Composition and function of intercalated discs in cardiac muscle tissue.
Stem keywords: Intercalated disc, composed of
Lead-in keywords: BEST, MOST RELEVANT CLUE
Negative lead-in flag: false

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E6 Physiology Guyton 4SAE Part 1 p. 50-52

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