Epithelial tissue Questions in English

(C) tissue is defined as a group of cells having a common origin and usually performing a common function. These cells may be of one type (simple tissue) or more than one type (complex tissue). Therefore,the most appropriate definition is that a group of one or more types of cells performing a common function is called a tissue.

(B) The basement membrane is a thin,fibrous,extracellular matrix that separates the epithelial tissue from the underlying connective tissue.
It is primarily composed of protein-bound mucopolysaccharides and glycoproteins,which are secreted by the epithelial cells,along with a layer of collagen or reticular fibers.

(B) In $Epithelial$ $tissue$, the cells are compactly packed with very little intercellular matrix.
$Epithelial$ $tissue$ forms a continuous sheet of cells that cover the body surface or line the body cavities.
In contrast, $Connective$ $tissue$ has an abundant intercellular matrix.
Therefore, the correct answer is $Epithelial$ $tissue$.

(B) The term "epithelium" was introduced in the $18^{th}$ century by the Dutch anatomist Frederik Ruysch. He coined this term to describe the fact that these tissues grow upon other tissues (epi = upon, thele = nipple/tissue).

(C) The basement membrane is a thin,fibrous,extracellular matrix of tissue that separates the lining of an internal or external body surface from underlying connective tissue. In the context of the provided options,the terms $Plasma \ membrane$ and $Plasmalemma$ are synonymous,referring to the same biological structure. However,the basement membrane itself is an extracellular structure,not a cell membrane. Given the options provided,if one must choose,the question implies a relationship between these terms. Since $Plasma \ membrane$ and $Plasmalemma$ are identical,option $(c)$ is the intended answer.

(D) The simple cuboidal epithelium is composed of a single layer of cube-like cells.
It is primarily found in the ducts of glands (such as sweat glands and salivary glands),the tubular parts of nephrons in the kidney,the ciliary body and choroid of the eye,and the thin bronchioles of the respiratory system.
Therefore,all the given options are correct locations for simple cuboidal epithelium.

(A) The ducts of certain large glands,such as the mammary gland and the parotid gland,as well as parts of the larynx and pharynx,are lined by stratified columnar epithelium.
This type of epithelium consists of multiple layers of cells where the superficial layer is columnar in shape,providing protection to the underlying tissues.

(A) The germinal epithelium is composed of specialized cuboidal epithelial cells.
These cells are found in the gonads (testes and ovaries) and are responsible for the production of gametes through the process of gametogenesis.
For example,they produce ova (female gametes) and sperm (male gametes).

(B) The correct answer is $B$.
Ciliated epithelium is found in the inner surface of hollow organs like bronchioles and fallopian tubes (uterine tubes).
In the trachea,the lining is specifically a pseudostratified ciliated columnar epithelium,which contains long ciliated columnar cells and short cuboidal cells.
Since both $B$ and $D$ contain ciliated epithelium,in the context of standard biology questions,$B$ (Trachea) is a primary site for this tissue type.

(C) The cells of squamous epithelium are thin,flattened,and scale-like. They fit together closely like tiles on a floor,forming a delicate lining.

(B) The internal surface of the large intestine,like the rest of the gastrointestinal tract,is lined by a mucous membrane.
This membrane consists of an epithelial tissue layer (specifically simple columnar epithelium) that provides protection,absorption,and secretion.
Therefore,the internal lining is primarily composed of epithelial tissue.

(D) $Stratified$ $squamous$ $epithelium$ occurs at surfaces subject to abrasion but protected from drying.
Thus, it forms the cornea of eyes, inner surfaces of eye lids, and the lining of the buccal cavity, lower part of the pharynx, oesophagus, vagina, and the vestibule of nasal cavities.

(B) Epithelial tissue covers the body surface and lines the internal organs and cavities.
Its primary functions include:
$1$. Protection: It acts as a barrier against mechanical injury,chemical stress,and pathogens.
$2$. Secretion: Glandular epithelium secretes substances like enzymes,hormones,and mucus.
$3$. Absorption: Epithelium in the digestive tract absorbs nutrients.
$4$. Sensation: Specialized sensory epithelial cells (e.g.,in the nose or tongue) help in detecting stimuli.
Therefore,the combination of protection,secretion,sensation,and absorption is correct.

(A) Simple epithelium is composed of a single layer of cells and functions as a lining for body cavities,ducts,and tubes.

(C) The epidermis of the skin is composed of a $\text{keratinized}$ $\text{stratified}$ $\text{squamous}$ $\text{epithelium}$.
These cells undergo a process called keratinization as they move toward the surface, where they eventually become dead, non-nucleated, and water-resistant, forming a protective barrier for the body.

(B) Ciliated epithelium consists of cells that bear cilia on their free surface. These cilia move particles or mucus in a specific direction over the epithelial surface. In vertebrates,specifically in the frog,ciliated epithelium is found in the lining of the buccal cavity and the oviducts. The cilia in the buccal cavity help in the movement of food,while in the oviducts,they facilitate the movement of ova.

(C) . The cells of simple squamous epithelium are flat,tile-like,and polygonal,with a centrally located oval or spherical nucleus.
It is also known as tessellated or pavement epithelium because the cells appear like tiles on a floor.

(A) Desmosomes are specialized adhesive protein complexes that occur at cell-cell junctions.
They are primarily found in epithelial tissues,where they provide mechanical strength by anchoring the intermediate filaments of the cytoskeleton to the plasma membrane,thereby holding adjacent cells together.
Therefore,the correct option is $A$.

(B) Simple epithelium consists of a single layer of cells that function as a lining for body cavities,ducts,and tubes.
Because these cells are closely packed and fitted together like tiles of a mosaic with very little intercellular matrix,they form a continuous,protective sheet.
This tight arrangement minimizes the friction and mechanical stress between individual cells,making the normal wear and tear of these cells negligible under standard physiological conditions.

(B) All somatic cells in a multicellular organism contain the same set of genetic information $(DNA)$. The differentiation of cells into specialized types,such as gland cells or epithelial cells,occurs due to differential gene expression. This means that in different cell types,specific sets of genes are turned 'on' (active) while others are turned 'off' (inactive),allowing cells to perform distinct physiological functions despite having identical genomes.

(A) . Epithelial tissue has a high capacity for cell division and regeneration.
Because epithelial cells are constantly exposed to wear and tear,they possess the ability to divide rapidly throughout the life of an organism.
This property allows for the quick repair of injuries and the healing of wounds,which is a characteristic feature of epithelial tissues compared to other tissue types.

(B) The epidermis of the skin in vertebrates consists of keratinized stratified squamous epithelium.
In this tissue,the cells of the upper layers are dead and contain an insoluble fibrous protein called keratin,which provides protection against abrasion and water loss.
While the buccal cavity also contains non-keratinized stratified squamous epithelium,the epidermis is the classic example of keratinized stratified squamous epithelium.

(A) The epithelial tissue forms the outer covering of the body and the lining of internal organs and cavities.
Specifically,the skin is covered by a layer of cornified epithelial cells that act as a barrier to protect the body against desiccation (drying),mechanical injury,and bacterial invasion.

(C) The oesophagus,cornea,and vagina are lined by non-keratinized stratified squamous epithelium.
This type of epithelium consists of multiple layers of cells where the surface cells are living and contain nuclei.
It provides protection against abrasion in moist environments where the surface does not need to be waterproofed by keratin.

(D) . Epithelial tissues possess a high capacity for regeneration and exhibit a rapid rate of cell division to replace damaged or worn-out cells. Unlike connective tissues,they are avascular (lack blood vessels) and have very little intercellular space between cells.

(B) The conjunctiva is a thin,transparent mucous membrane that covers the inner surface of the eyelids and the anterior part of the sclera.
Histologically,the conjunctiva is lined by a stratified columnar epithelium,which contains goblet cells that secrete mucus to keep the eye surface moist.
Therefore,the correct answer is $B$.

(A) The outer layer of the skin,known as the epidermis,consists of keratinised stratified squamous epithelium.
This tissue contains the protein keratin,which makes the skin tough and waterproof.
Because the skin is the outermost layer of the body,it is constantly exposed to the external environment,making it susceptible to mechanical stress,friction,and abrasion.
Therefore,the keratinised nature of the epithelium provides protection against such wear and tear.

(B) The correct answer is $B$.
Simple columnar epithelium is a type of epithelial tissue composed of a single layer of tall,narrow cells.
This tissue is specifically found lining the stomach,the small intestine,and the large intestine,where it plays a crucial role in the absorption of nutrients and the secretion of mucus and enzymes.

(B) Pseudostratified columnar epithelium is a type of epithelium that appears to be stratified because the nuclei of the cells are at different levels,but all cells are in contact with the basement membrane.
In humans,this tissue is commonly found in the respiratory tract (trachea,bronchi) and the male urethra.
Therefore,among the given options,the male urethra is the correct site for this tissue.

(D) Epithelial tissues are derived from all three primary germ layers during embryonic development:
$1$. $Ectoderm$: Gives rise to the epidermis of the skin and the lining of the mouth and anus.
$2$. $Mesoderm$: Gives rise to the mesothelium,which lines the body cavities (pericardial,pleural,and peritoneal cavities) and the endothelium of blood vessels.
$3$. $Endoderm$: Gives rise to the epithelium lining the alimentary canal and respiratory tract.
Therefore,the correct answer is $D$.

(B) The inner surface of hollow organs like the fallopian tubes,bronchi,and bronchioles is lined with ciliated epithelium.
These cells possess cilia on their free surface.
The primary function of these cilia is to move particles or mucus in a specific direction over the epithelial surface.
In the fallopian tubes,the cilia help in the movement of the ovum,while in the bronchi and bronchioles,they help in clearing mucus and trapped dust particles.

(A) In animals,gametes are produced by the germinal epithelium,which is a specialized type of epithelial tissue found in the gonads (testes and ovaries). The cells of the germinal epithelium undergo meiosis to produce haploid gametes (sperm or ova).

(B) The correct answer is $B$. Pseudostratified epithelium is a type of simple epithelium that appears to be stratified because the nuclei are located at different levels,but all cells are in contact with the basement membrane.
It is primarily found in the lining of the respiratory tract,specifically in the trachea,large bronchi,and also in the male urethra and certain salivary glands.

(C) Epithelial tissue is considered the first tissue to evolve in animals.
It forms the protective covering of the body and lines the internal cavities and organs.
In primitive multicellular organisms like sponges and cnidarians,epithelial-like cells are the primary structural components,establishing the foundation for the development of more complex tissues later in evolutionary history.

(C) . Ependymal cells are a type of neuroglial cells that form the epithelial-like lining of the central canal of the spinal cord and the ventricles of the brain. They are involved in the production and circulation of cerebrospinal fluid $(CSF)$.

(A) Sweat glands are classified as simple coiled tubular glands.
These glands are located in the dermis of the skin.
They consist of a single unbranched duct (simple) and a secretory portion that is coiled into a ball-like structure (coiled tubular).

(C) Sweat glands,specifically the eccrine sweat glands,are classified as merocrine glands.
In merocrine secretion,the secretory product is released from the cell via exocytosis without any loss of cellular cytoplasm or damage to the cell itself.
This is the most common mode of secretion in the human body.

(C) The correct answer is $C$.
Merocrine glands are those in which the secretory product is released via exocytosis through the cell membrane without any loss of cellular material.
Examples include the salivary glands,pancreas,and goblet cells.
In contrast,sebaceous glands are holocrine,and mammary glands are apocrine.

(A) The mammary gland is classified as an apocrine gland.
In apocrine glands,the secretory products accumulate at the apical portion of the secretory cell.
During secretion,this apical part of the cell pinches off along with the secretory product,while the remaining part of the cell stays intact.
The cell then repairs the lost portion,which is a characteristic feature of mammary glands.

(A) Epithelial tissue is highly regenerative in nature.
When injured,these cells divide and regenerate more rapidly than other tissues.
This high rate of cell division and regeneration facilitates the rapid healing of wounds.

(D) Tonofibrils are bundles of intermediate filaments that anchor to desmosomes in epithelial cells. They play a crucial role in maintaining the structural integrity and mechanical strength of tissues by connecting the cytoskeleton of adjacent cells. Therefore,they are associated with desmosomes.

(B) The inner lining of the gut (intestine),stomach,and liver is composed of simple columnar epithelium.
This tissue consists of a single layer of tall,slender,rectangular cells.
These cells often contain goblet cells for mucus secretion and have nuclei located at the base of the cell.

(B) The mucosal lining of the oesophagus in mammals is composed of $Stratified$ $squamous$ $epithelium$.
This type of tissue consists of multiple layers of cells.
The basal layers are cuboidal or columnar,while the surface layers are flattened and scale-like,providing protection against mechanical abrasion during the passage of food.

(C) The brush bordered epithelium is characterized by the presence of microvilli on the apical surface of the epithelial cells.
These microvilli significantly increase the surface area for the absorption of nutrients.
This type of epithelium is specifically found in the lining of the small intestine,where maximum absorption of digested food occurs.

(A) Goblet cells are specialized unicellular glandular cells that secrete mucus.
They are found scattered within the epithelial lining of the digestive tract (such as the intestine) and the respiratory tract.
Since they consist of a single cell,they are classified as unicellular glands.
Therefore,the correct option is $A$.

(C) During embryonic development,the three primary germ layers are formed: Ectoderm,Mesoderm,and Endoderm.
$1$. The $Ectoderm$ gives rise to the epidermis of the skin,the nervous system,and the lining of the mouth and anus.
$2$. The $Mesoderm$ gives rise to muscles,bones,the circulatory system,and the dermis of the skin.
$3$. The $Endoderm$ gives rise to the epithelial lining of the digestive tract and respiratory system.
Therefore,the epidermis of the skin is derived from the $Ectoderm$.

(B) When individuals perform hard manual labor,the constant friction and mechanical stress on the skin of their palms stimulate the basal layer of the epidermis to increase cell division. This results in the formation of a thickened layer of keratinized cells,known as the stratum corneum,which serves as a protective adaptation to prevent injury. Therefore,the epidermis on their palms becomes significantly thicker.

(C) The epidermis is the outermost layer of the skin and serves as the primary protective barrier of the body.
It undergoes a process called keratinization,where cells produce keratin,a tough,fibrous protein.
This layer protects the underlying tissues from mechanical injury,pathogens,and excessive water loss.

(B) Nails,horns,and hooves are structural components of animals that are primarily composed of a tough,fibrous structural protein known as $Keratin$. $Keratin$ is a type of scleroprotein that provides strength and protection to these body parts. $Chitin$ is a polysaccharide found in the exoskeleton of arthropods and fungal cell walls,not in mammalian nails or horns.

(A) The inner lining of hollow organs like the nasal passage,bronchi,and fallopian tubes is lined with ciliated columnar epithelium.
These cells possess cilia on their free surface.
The rhythmic movement of these cilia helps in the movement of particles or mucus in a specific direction.
In the nasal passage and bronchi,they move mucus and trapped dust particles,while in the fallopian tubes,they facilitate the movement of the ovum.