Question

The cell junction namely tight, adhering and gap junctions are found in
(a) Connective tissue
(b) Epithelial tissue
(c) neural tissues
(d) Muscular tissues

Answer 1

Hint: The cell junctions such as tight junction, adhering and gap junctions are present in tissues which form the outer layer of all body surfaces, line body cavities and hollow organs, and which forms major tissue in glands. These tissues perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception. In them the cells are densely packed together with a minimal amount of intercellular substance and are firmly attached by intercellular junctions.

Complete step by step answer:
The cells of Epithelial tissues are held together by cell junctions such as tight, adhering and gap junctions. The epithelial tissues consist of variously shaped cells. The cells are closely arranged without or minimal intercellular spaces. They are one of the four different types of tissues. There are three principal shapes of epithelial cells: squamous, columnar, and cuboidal. These can be arranged in a single layer of cells as simple epithelium, either squamous, columnar, or cuboidal or in layers of two or more cells deep as stratified squamous, columnar or cubical. Epithelial cells form the outer covering of different organs, blood vessels, etc. and inner layer of cavities of certain internal organs. All glands are made up of epithelial cells. Functions of epithelial cells include secretion, selective absorption, protection, trans- cellular transport, and sensing. It is a thin, continuous, protective layer of cells. Cell junctions are well-employed in epithelial tissues.
So, the correct answer is ‘(b) Epithelial tissue’.

Additional Information:
- The lining of the mouth, lung alveoli and kidney tubules are all made of epithelial tissue.
- The lining of the blood, and lymphatic vessels are of a specialized form of epithelium called endothelium.
- The outermost layer of human skin is composed of dead, squamous, keratinized epithelial cells

Note:
- Cell junctions are classes of cell structure containing a multiprotein complex which provides adhesion between adjacent cells or between the cell and extracellular matrix.
- There are mainly 5 different types of cell junctions: tight junctions, adhering , desmosomes, hemidesmosomes, and gap junctions.
- Gap junctions connect the cytoplasm of two cells Adhering junctions are a plaque which attaches both cells’ microfilaments. Tight junctions are a pair of trans- membrane protein fused on the outer plasma membrane.