Which of the following statements is NOT correct about intercellular junctions?
A Adherens junctions are essential for the cells to communicate in all the four basic types of tissue.
B Blood-brain barrier and outer layer of skin have tight junctions
C Gap junctions connect cardiac muscle cells and allow them to communicate with each other fast.
D Desomsomes are intercellular interactions between epithelial cells
E Intercellular junctions connect cell membrane between neighboring cells.
The correct answer and explanation is:
Correct Answer: A. Adherens junctions are essential for the cells to communicate in all the four basic types of tissue.
Explanation (300 words):
Intercellular junctions are specialized structures that connect adjacent cells, playing crucial roles in communication, adhesion, and maintaining the structural integrity of tissues. Let’s analyze each option:
A. “Adherens junctions are essential for the cells to communicate in all the four basic types of tissue.” – Incorrect (thus the correct answer)
Adherens junctions are primarily involved in cell adhesion, not cell-to-cell communication. They link the actin cytoskeleton of one cell to that of its neighbor through cadherins, helping to maintain tissue integrity, particularly in epithelial and cardiac tissues. However, they are not essential for communication across all tissue types (epithelial, muscle, nervous, and connective tissues). Communication is mostly mediated by gap junctions, especially in cardiac and neural tissues.
B. “Blood-brain barrier and outer layer of skin have tight junctions” – Correct
Tight junctions form a seal between adjacent cells, preventing the passage of substances through the space between cells. They are especially critical in the blood-brain barrier, where selective permeability is essential, and in the epidermis, to protect against external environments.
C. “Gap junctions connect cardiac muscle cells and allow them to communicate with each other fast.” – Correct
Gap junctions allow direct cytoplasmic exchange of ions and small molecules between adjacent cells. In the heart, they are vital for the rapid propagation of action potentials, ensuring synchronized contraction.
D. “Desmosomes are intercellular interactions between epithelial cells” – Correct
Desmosomes are strong, adhesive junctions found in epithelial tissues, anchoring cells together and providing mechanical strength, especially in skin and mucosa.
E. “Intercellular junctions connect cell membrane between neighboring cells.” – Correct
This is a general but accurate statement. All types of intercellular junctions (tight, adherens, desmosomes, gap) function at the cell membrane interface between adjacent cells.
Therefore, Option A is NOT correct about intercellular junctions.