Test: Epithelial Tissue - NEET MCQ

A simple squamous epithelium is a single layer of flat cells in contact with the basal lamina (one of the two layers of the basement membrane) of the epithelium. This type of epithelium is often permeable and occurs where small molecules need to pass quickly through membranes via filtration or diffusion.

This epithelium is present in/the terminal bronchioles and alveoli of the lungs, walls of Bowman's capsules and descending limb of loop of Hen Ie. In the blood vessels and heart it is called endothelium. In coelom, it is called as mesothelium.

The loop of Henle is the U-shaped portion of the nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. The curved portion of Henle's loop is lined by squamous epithelium. The squamous epithelium enables rapid diffusion of blood and diffusion of small molecules.
So, the correct answer is 'Squamous epithelium'.

The Germinal epithelium or epithelial cells are the ones present in the reproductive organs of animals, such as testis and ovary. These are the cells which divide and redivide itself to form the male and female gametes.

There is a structural difference between a kinocilium (which is a true cilium, having a 9+2 microtubule arrangement), and stereocilia (which don't have microtubules, instead they have actin cores).  

Pseudo-stratified epithelium : It is the simple columnar epithelium in which the regular arrangement of the cells is distorted. The cells of this type of epithelium are also twisted with respect to each other giving a false appearance. Cells are arranged in single layer, but appear multi-layered. This type of epithelium is present in the inner linings of trachea, large bronchi and helps to remove mucus. 

A desmosome, also known as a macula adhaerens, is a cell structure specialized for cell-to-cell adhesion. They are transmembrane proteins that bridge the space between adjacent epithelial cells by way of homophilic binding of their extracellular domains to other desmosomal cadherins on the adjacent cell. 

Squamous epithelium (labelled c) is composed of large flat cells whose edges fit closely together like the tiles in a floor, hence it is also called pavement epithelium or tessellated epithelium. The cells rest on a thin basement membrane. If the cells are seen from the surface, they seem to be polygonal in shape. 

The correct answer is A: Urethra of male and parotid salivary gland. Here's why:

- Pseudostratified non-ciliated columnar epithelial tissue lines parts of the male urethra and the parotid salivary gland.
- In the male urethra, this tissue provides protection and facilitates secretion.
- In the parotid salivary gland, it helps in secretion and protection.

Understanding the specific locations where this tissue is found helps in identifying the correct answer.

Bronchi are tube like structures that allow air to be transported from the surrounding atmosphere to the lung. The respiratory system (airways) consists of the trachea (essentially a large bronchi) that branch off into smaller and smaller bronchi before reaching the most distal lung alveoli, where oxygen can be transferred to the blood.

The respiratory bronchus is lined by respiratory epithelium comprising an admixture of pseudostratified ciliated columnar epithelium, goblet cells (mucin producing cells also termed mucous cells) and basal cells that function as progenitor cells for both the ciliated columnar cells and goblet cells. 

Transitional epithelium is much thinner and more stretchable than the stratified epithelium. It has a single layer of cuboidal cells at the base, two to three middle layers of a large polygonal or pear-shaped cells and a superficial layer of large, broad, rectangular or oval cells.

Histologists have recognized two more types of epithelia, which cannot be included in any of the types of covering epithelia. One is the neuroepithelial cell of epithelial origin. These cells are specialised for sensory functions, e.g. cells of taste bud. The other one is myoepithe-lial cell, which are branched cells, which con-tain muscle proteins, such as myosin and actin. 

The areolar tissue joins different tissues and forms the packing between them and helps to keep the organs in place and in normal shape.

Transitional epithelium is a stratified tissue made of multiple cell layers, where the cells constituting the tissue can change shape depending on the distention in the organ. When the organ is filled with fluid, cells on the topmost layer of this epithelium can stretch and appear flattened. Alternately, they can also appear cuboidal with a rounded shape when the fluid pressure is low.

This epithelium is found lining the urinary bladder, ureters and urethra, as well as in the ducts of the prostrate gland.

The epithelial lining of the gall bladder consists of simple columnar cells specialized for absorption, with an apical brush border of microvilli, very similar to intestinal absorptive cells.  However, unlike intestinal epithelium, gall bladder epithelium includes only this single cell type; it has no goblet cells.

Solution: Squamous epithelium is made of a single thin layer of flattened cells, which is ideally suited for areas where diffusion or filtration processes occur, such as in the air sacs of lungs. This structure allows for efficient gas exchange between the air in the lungs and the blood in the capillaries. An interesting fact is that the thinness of squamous cells facilitates rapid diffusion of oxygen and carbon dioxide, making our breathing process efficient.

Correct Answer :- a

Explanation : The palatine tonsil is composed of lymphoid tissue within which are channels lined by squamous epithelium—crypts—that open onto the surface. It is part of a ring of lymphoid tissue in the oral cavity and nasopharynx—Waldeyer’s ring—which includes also the lingual tonsil at the base of the tongue and the pharyngeal tonsil or adenoid in the nasopharynx. There are about 20 crypts reaching the deepest part of the structure. Submucosal glands lie in the peripheral part.

Flame cells are specialized cells in flatworms that play a crucial role in excretion and osmoregulation. They help in the removal of waste materials and the regulation of water and ion balance within the flatworm's body. This system is essential for maintaining homeostasis in the absence of a circulatory system for transporting nutrients and wastes.

Endothelium refers to cells that line the interior surface of blood vessels and lymphatic vessels, forming an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. It is a thin layer of simple, or single-layered, squamous cellscalled endothelial cells. Endothelial cells in direct contact with blood are called vascular endothelial cells, whereas those in direct contact with lymph are known as lymphatic endothelial cells.

Cnidarians, such as jellyfish, corals, and sea anemones, exhibit radial symmetry and have a simple body plan that can alternate between two distinct forms: the sessile polyp and the free-swimming medusa. This unique life cycle allows them to exploit different ecological niches during their life. Bilateral symmetry and a complete digestive system are characteristics of more complex animals, segmented bodies and chitin exoskeletons describe arthropods, and a pseudocoelom with a complete digestive tract describes nematodes.

Cuboidal epithelia have a cube-like shape; that is, their width is approximately equal to their height. They may exist in single layers or multiple layers depending on their location in the body.

The Bartholin's glands (also called Bartholin glands or greater vestibular glands) are two pea-sized compound racemose glands which are located slightly posterior and to the left and right of the opening of the vagina. They secrete mucus to lubricate the vagina. They are composed of cuboidal epithelium.

Chondrichthyes, which includes sharks, rays, and skates, are characterized by having a cartilaginous endoskeleton. Unlike bony fishes and other vertebrates, the skeletons of these animals are made entirely of cartilage, which is lighter and more flexible. Amphibia, Reptilia, and Mammalia typically have bony skeletons.

The corneal epithelium is the outermost layer of the cornea. It is composed of a single layer of basal cells and 4-5 cell layers of nonkeratinized, stratified squamous epithelial cells, which are held together by tight junctions, to form an effective barrier against fluid loss and pathogen penetration.

Epithelial tissues are derived from all of the embryological germ layers:

• from ectoderm (e.g., the epidermis)
• from endoderm (e.g., the lining of the gastrointestinal tract)
• from mesoderm (e.g., the inner linings of body cavities)

However, it is important to note that pathologists do not consider endothelium and mesothelium (both derived from mesoderm) to be true epithelium. This is because such tissues present very different pathology. For that reason, pathologists label cancers in endothelium and mesothelium sarcomas, whereas true epithelial cancers are called carcinomas. Additionally, the filaments that support these mesoderm-derived tissues are very distinct. Outside of the field of pathology, it is generally accepted that the epithelium arises from all three germ layers.

Simple columnar epithelium
Cells are elongated and column-shaped. Their nuclei are elongated and are usually located near the base of the cells.
Columnar epithelium is found in the following:
The lining of the stomach and intestines.
Some columnar cells are specialized for sensory reception such as in the nose, ears and the taste buds of the tongue.
Also have surface modifications such as cilia and microvilli and
Goblet cells (unicellular glands) are found between the columnar epithelial cells of the duodenum.
Function: secretion and absorption.

They are found in lining of mouth cavity, tongue, pharynx, oesophagus and vagina. Keratinized stratified epithelium- This tissue is found on outer dry surfaces of body like skin, hair claws and nails. The outer surface layer consists of deadepithelial cells.

Cells of Peritoneum comprise:
- Squamous Epithelium: Squamous epithelial cells are flat and thin, resembling scales. They are the most common type of cells found in the peritoneum.
Other types of epithelial cells that can be found in the peritoneum include:
- Ciliated Epithelium: Ciliated epithelial cells have hair-like structures called cilia on their surface. These cells are found in areas such as the fallopian tubes and respiratory tract.
- Glandular Epithelium: Glandular epithelial cells are specialized for secretion and are found in glands throughout the body. They secrete substances such as mucus, enzymes, and hormones.
- Columnar Epithelium: Columnar epithelial cells are tall and slender, with a rectangular shape. They are found in areas such as the intestines, where they help with absorption and secretion.
It is important to note that the peritoneum is a membrane that lines the abdominal cavity and covers the organs within it. It consists of a layer of mesothelial cells, which are a type of epithelial cell. These cells secrete a fluid that lubricates the organs and allows them to slide against each other during movement.
In conclusion, the cells of the peritoneum comprise squamous epithelium, ciliated epithelium, glandular epithelium, and columnar epithelium, with squamous epithelium being the most common type.

Ciliated epithelium performs the function of moving particles or fluid over the epithelial surface in such structures as the trachea, bronchial tubes, and nasal cavities. 

A ciliated columnar epithelium lines the lumen of the uterine tube, where currents generated by the cilia propel the egg cell toward the uterus. They are also present in the buccal cavity of frog.

Simple cuboidal epithelium consists of a monolayer of epithelial cells that appear to be square-shaped in cross section. With large, rounded, centrally located nuclei, all the cells of this epithelium are directly attached to the basement membrane.
A monolayer of cuboidal epithelial cells covers the ovary and forms the ovarian surface epithelium. It plays a role in repairing the damage caused during every ovulation event and may also support the formation of an ovum.

Epidermis of the skin of vertebrates comprises stratified epithelium. Stratified epithelia are cover the exterior body surfaces and lining portions of the body tracts, where friction occurs. A multilayered epithelium allows deeper cells to replace the most superficial cells, as they are damaged or cast off from the epithelial surface.