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Which of the following is NOT a characteristic of epithelial tissue?
Which of the following is NOT a characteristic of epithelial tissue?
Epithelial tissue can only be formed from the ectodermal layer of the embryo.
Epithelial tissue can only be formed from the ectodermal layer of the embryo.
False
What type of transport primarily facilitates the absorption of oxygen across the epithelial cells in the lungs?
What type of transport primarily facilitates the absorption of oxygen across the epithelial cells in the lungs?
Diffusion
The type of epithelium that consists of multiple layers of cells is called __________.
The type of epithelium that consists of multiple layers of cells is called __________.
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Match the types of glands with their characteristics:
Match the types of glands with their characteristics:
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Which of the following functions is NOT performed by epithelial tissue?
Which of the following functions is NOT performed by epithelial tissue?
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The apical surface of epithelial tissue may have structures such as cilia and microvilli.
The apical surface of epithelial tissue may have structures such as cilia and microvilli.
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Name one way epithelial tissue provides protection.
Name one way epithelial tissue provides protection.
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Which secretion mechanism involves the disintegration of the entire cell?
Which secretion mechanism involves the disintegration of the entire cell?
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Merocrine secretion is the most common mechanism of secretion in multicellular glands.
Merocrine secretion is the most common mechanism of secretion in multicellular glands.
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What is the shape of the secretory part for tubulo-alveolar glands?
What is the shape of the secretory part for tubulo-alveolar glands?
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Goblet cells are an example of a __________ gland.
Goblet cells are an example of a __________ gland.
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Match the following gland types with their secretion mechanism:
Match the following gland types with their secretion mechanism:
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Which of the following epithelial junctions is primarily responsible for maintaining the integrity of the epithelium?
Which of the following epithelial junctions is primarily responsible for maintaining the integrity of the epithelium?
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Gap junctions are responsible for the passage of molecules between epithelia via tight junctions.
Gap junctions are responsible for the passage of molecules between epithelia via tight junctions.
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What type of secretion mechanism involves glandular cells retaining their structure while releasing their secretions?
What type of secretion mechanism involves glandular cells retaining their structure while releasing their secretions?
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What is the primary function of microvilli?
What is the primary function of microvilli?
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Stereocilia are motile extensions found in the inner ear.
Stereocilia are motile extensions found in the inner ear.
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What are the primary structural components of cilia and flagella?
What are the primary structural components of cilia and flagella?
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Microvilli are covered by a layer of __________ that aids in absorption.
Microvilli are covered by a layer of __________ that aids in absorption.
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Match the following structures with their definitions:
Match the following structures with their definitions:
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How many actin filaments are typically found in a bundle within each microvillus?
How many actin filaments are typically found in a bundle within each microvillus?
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Flagella exhibit a beating pattern similar to that of cilia.
Flagella exhibit a beating pattern similar to that of cilia.
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What proteins anchor the actin filaments in stereocilia?
What proteins anchor the actin filaments in stereocilia?
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Study Notes
Histology I (Epithelial Tissue)
- Epithelial tissue covers surfaces or lines cavities throughout the body
- Constructed of densely packed cells with minimal intercellular spaces
- Rests on a basement membrane for support
- Exhibits a high regeneration rate
- Displays polarity (apical, lateral, and basal surfaces)
- Lateral and basal surfaces have specialized junctions
- Apical surface may have microvilli, stereocilia, cilia, or flagella
- Avascular; obtains nutrients via diffusion through the basement membrane from underlying connective tissue
- Originates from all three embryonic germ layers: ectoderm, endoderm, and mesoderm
Types of Tissues
- Epithelial Tissue: Composed of aggregated polyhedral cells; small extracellular matrix; lines surfaces and forms glands.
- Connective Tissue: Composed of several fixed and wandering cells; abundant extracellular matrix; supports and protects
- Muscle Tissue: Composed of elongated contractile cells; moderate extracellular matrix; facilitates movement
- Nervous Tissue: Composed of elongated cells with fine processes; very small extracellular matrix; transmits nerve impulses
Function of Epithelium Tissue
- Transports molecules (diffusion, carrier-mediated, and vesicle-mediated)
- Absorbs substances (endocytosis, pinocytosis)
- Secretes various molecules (exocytosis)
- Protects against abrasion and injury.
- Exhibits selective permeability maintaining different compositions on the cell's exterior and interior surfaces (e.g., kidney)
Covering, Lining, and Surface Epithelium
- Simple Epithelium: One layer of cells
- Stratified Epithelium: Multiple layers of cells. This type are grouped by cell shape and include simple squamous, simple cuboidal, simple columnar, pseudostratified columnar, stratified squamous (non-keratinized & keratinized), stratified cuboidal, stratified columnar, and transitional.
Types of Epithelial Cells
- Based on cell shape and number of layers, several types of epithelial cells have unique structures and functions in various areas of the body. Examples include squamous, cuboidal, and columnar cells, stratified and simple cells, as well as transitional cells.
Secretory or Glandular Epithelium
- Exocrine glands: Possess ducts that deliver secretions to body surfaces or cavities.
- Endocrine glands: Lack ducts; secrete hormones directly into the bloodstream.
- Mixed glands: Contain both exocrine and endocrine components (e.g., pancreas)
Classification of Exocrine Glands
- Number of cells: Unicellular (e.g., goblet cells) and multicellular.
- Mechanism of secretion: Merocrine, apocrine, and holocrine.
- Branching of duct: Simple or compound.
- Shape of secretory part: Tubular, alveolar, or tubuloalveolar. Categorization of exocrine glands according to these factors helps understand their specific structures and roles in different body systems.
Apical Epithelial Surfaces
- Microvilli: Tiny, finger-like projections increasing surface area (e.g., intestinal lining, kidney tubules)
- Stereocilia: Especially long and non-motile microvilli (e.g., inner ear, epididymis)
- Cilia and Flagella: Hair-like extensions that beat to move substances (e.g., respiratory tract, female reproductive tract)
- Specialized arrangements of cytoskeletal components enable different types of functional cell movement.
- Cilia have characteristic 9+2 axoneme arrangement providing functionality for moving secretions.
Intercellular Junctions
- Tight Junctions: Close cells together.
- Adherens Junctions: Strengthen tight junctions.
- Desmosomes: Link cytoskeletons, strengthening cells.
- Gap Junctions: Allow cell-to-cell communication.
- Hemidesmosomes: Anchor cells to the basement membrane. Specialized connections mediate cell interactions and maintain tissue integrity.
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Description
This quiz covers the fundamental elements of epithelial tissue. Focus on its characteristics, functions, types, and origins from the embryonic germ layers. Test your understanding of how this tissue supports various bodily functions.
