Epithelial Tissue Overview

Questions and Answers

What is the primary function of simple cuboidal epithelium?

Transport of materials

Sensation and perception

Protection against mechanical stress

Secretion and absorption (correct)

What role does enactin/nidogen play in the structure of epithelial tissues?

It aids in nutrient absorption

It holds laminin and type IV collagen together (correct)

It promotes cell division

It provides tensile strength to the cells

Which characteristic is NOT true of epithelial tissues?

Cells are arranged in layers or sheets

Cells are highly vascularized (correct)

Cells are closely adherent to each other

Cells rest on the basal lamina

Which is an example of simple columnar ciliated epithelium?

Cells in the uterus Signup and view all the answers

What happens when epithelial cells undergo metaplasia due to prolonged irritation?

They transform into a different cell type better suited to resist irritants Signup and view all the answers

Which of the following is a function of epithelial tissues?

Secretion Signup and view all the answers

What characteristic of epithelial cells allows for nutrient absorption?

Avascular nature and diffusion capacity Signup and view all the answers

Which of the following best describes the arrangement of simple columnar epithelium?

Single layer of columnar cells Signup and view all the answers

Which type of epithelium consists of several layers with the uppermost layer being formed of living cells?

Stratified squamous non-keratinized epithelium Signup and view all the answers

What type of glands pour their secretions through a duct system?

Exocrine glands Signup and view all the answers

What is a key characteristic of stratified squamous keratinized epithelium?

Presence of keratin in the uppermost layer Signup and view all the answers

Which of the following is an example of stratified squamous non-keratinized epithelium?

Oral mucosa Signup and view all the answers

Which cell type is a common example of a unicellular gland?

Goblet cell Signup and view all the answers

What type of secretion is characteristic of endocrine glands?

Directly into the bloodstream Signup and view all the answers

How can stratified squamous epithelium be subdivided?

By the state of the uppermost layer of cells Signup and view all the answers

Which of the following is NOT a type of gland based on the number of cells?

Keratinized gland Signup and view all the answers

Which type of gland produces a thin, watery secretion?

Serous glands Signup and view all the answers

What type of secretion is primarily produced by goblet cells?

Mucous secretion Signup and view all the answers

Which gland is predominantly serous?

Parotid glands Signup and view all the answers

If a gland is classified as simple tubular, which of the following is an example?

Fundic glands Signup and view all the answers

Which type of gland is characterized by having secretory products exit via exocytosis without losing cytoplasm?

Merocrine gland Signup and view all the answers

What type of gland is the mammary gland classified as?

Compound alveolar Signup and view all the answers

Which type of gland is primarily responsible for producing gametes?

Cytogenic glands Signup and view all the answers

Which of the following is an example of a compound tubulo-acinar gland?

Submandibular glands Signup and view all the answers

What type of cell secretion involves the complete destruction of the cell?

Holocrine secretion Signup and view all the answers

Which of the following is true about zonula occludens?

It forms a selective permeable barrier. Signup and view all the answers

Which cell adhesion molecule is critical for maintaining cell cohesion?

Cadherin Signup and view all the answers

What is a characteristic of apocrine glands?

They secrete products along with some cytoplasm and membrane. Signup and view all the answers

How do cadherins contribute to cell adhesion?

By linking neighboring cell membranes. Signup and view all the answers

What component is found in the basal lamina?

Proteoglycans Signup and view all the answers

Which type of gland releases secretory products via exocytosis with cell membrane retained?

Merocrine gland Signup and view all the answers

What is the function of claudin in junctional complexes?

To contribute to the sealing function Signup and view all the answers

What is the primary function of connexons in cell communication?

They permit passage of ions and small molecules between cells. Signup and view all the answers

Which structural feature is characteristic of motile cilia?

9+2 assembly of microtubules. Signup and view all the answers

Which protein acts as an anchoring component binding cytoplasmic side of cell membranes to intermediate filaments?

Desmoplakin Signup and view all the answers

In which type of epithelium are hemidesmosomes primarily found?

Stratified epithelium Signup and view all the answers

What role do kinesin and dynein play in cellular function?

They are involved in molecular transport within cells. Signup and view all the answers

Which of the following is NOT a characteristic of gap junctions?

They are found only in epithelial tissue. Signup and view all the answers

What is the main purpose of plakoglobin in cellular structures?

To anchor intermediate filaments to cell membranes. Signup and view all the answers

Which type of tissue would you find abundant motile cilia?

Cuboidal epithelium Signup and view all the answers

Study Notes

Simple Cuboidal Epithelium

Composed of a single layer of cuboidal cells.
Laminin: Glycoproteins forming a network beneath cells for secretion and absorption.
Enactin/nidogen and perlecan hold laminin and type IV collagen together.
Examples include thyroid follicles, germinal epithelium of ovaries, and distal convoluted tubules of kidneys.
Associated with reticular fibers forming the reticular lamina.

Characteristics of Epithelial Tissues

Cells tightly adhere to one another, arranged in layers or sheets.
Avascular; receive nutrients only through diffusion.
Rest on a basal lamina, continuously renewed and replaced.
Can undergo metaplasia due to prolonged irritation, transforming into a more suitable type for resistance.

Simple Columnar Epithelium

Consists of a single layer of columnar cells aiding in absorption.
Examples include cells lining the gastrointestinal tract and the gallbladder.

Simple Columnar Ciliated Epithelium

Features a single layer of columnar cells equipped with cilia.
Functions to facilitate movement of substances.
Examples include the uterus and fallopian tube.

Stratified Squamous Epithelium

Comprised of several layers, with the uppermost layer being flattened or squamous.
Subdivided into:
- Non-keratinized: Living cells in the upper layer (e.g., esophagus, vagina).
- Keratinized: Upper layer consists of dead cells (e.g., epidermis, hard palate).

Glandular Epithelium

Classification based on the number of cells, type of secretion, structure, and mode:
- Unicellular: Formed by a single cell (e.g., goblet cell).
- Multicellular: Composed of multiple cells, can be exocrine (uses ducts) or endocrine (secretes directly into the blood).

Types of Secretion

Serous: Thin and watery (e.g., parotid glands).
Mucous: Thick and viscous (e.g., goblet cells).
Muco-serous: Mixed secretions (e.g., submandibular glands).

Structure of Multicellular Glands

Tubular: Simple tubular, coiled tubular, branched tubular, compound tubular.
Alveolar: Simple, branched, and compound types.
Tubulo-acinar: Mixed, such as salivary glands.

Modes of Secretion

Merocrine: Secretion without loss of cytoplasm (e.g., eccrine sweat glands).
Apocrine: Secretion with partial loss of cytoplasm (e.g., mammary glands).
Holocrine: Total cell loss with secretion (e.g., sebaceous glands).

Junctional Complexes and Cell Cohesion

Zonula occludens: Tight junctions that create a barrier between epithelial layers.
Connections through cell adhesion molecules such as cadherins.
Nexus: Gap junctions allowing communication between adjacent cells via connexons.

Hemidesmosomes

Specialized structures anchoring basal cells to the basal lamina.
Important in stratified epithelium for resistance to mechanical stress.

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Description

This quiz covers the characteristics and examples of various types of epithelial tissues, including simple cuboidal and columnar epithelia. Explore the structures, functions, and specialized forms of these tissues as you test your knowledge on their roles in the human body.