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Questions and Answers
What is the primary role of the apical domain in epithelial cells?
What is the primary role of the apical domain in epithelial cells?
Which of the following are specialized forms of covering epithelium?
Which of the following are specialized forms of covering epithelium?
Which structure is primarily associated with increasing the surface area for absorption in epithelial cells?
Which structure is primarily associated with increasing the surface area for absorption in epithelial cells?
What is the clinical significance of membrane specialization in epithelial cells?
What is the clinical significance of membrane specialization in epithelial cells?
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In what type of epithelial cells would you expect to find a significant presence of aquaporins?
In what type of epithelial cells would you expect to find a significant presence of aquaporins?
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Which of the following specialized epithelial structures is NOT typically found in the apical domain?
Which of the following specialized epithelial structures is NOT typically found in the apical domain?
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What is the main function of the glycocalyx associated with microvilli?
What is the main function of the glycocalyx associated with microvilli?
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What is the primary function of integrins in hemidesmosomes?
What is the primary function of integrins in hemidesmosomes?
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Which component is NOT part of the basal lamina?
Which component is NOT part of the basal lamina?
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Which feature distinguishes exocrine glands from endocrine glands?
Which feature distinguishes exocrine glands from endocrine glands?
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What characterizes metaplasia in epithelial cells?
What characterizes metaplasia in epithelial cells?
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What happens if malignant cells cross the basal lamina?
What happens if malignant cells cross the basal lamina?
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What primarily enables stereocilia to maintain their rigidity?
What primarily enables stereocilia to maintain their rigidity?
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What is the primary organization of the axoneme in a cilium?
What is the primary organization of the axoneme in a cilium?
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Which feature is NOT associated with the basolateral domain of epithelial cells?
Which feature is NOT associated with the basolateral domain of epithelial cells?
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What condition results from defects in ciliary dynein, impacting ciliary movement?
What condition results from defects in ciliary dynein, impacting ciliary movement?
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What is one of the critical functions of hemidesmosomes in epithelial cells?
What is one of the critical functions of hemidesmosomes in epithelial cells?
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Which of the following is true regarding cilia and their movement?
Which of the following is true regarding cilia and their movement?
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What characteristic distinguishes stereocilia from typical cilia?
What characteristic distinguishes stereocilia from typical cilia?
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What role do the finger-like enfoldings of the basal plasma membrane serve?
What role do the finger-like enfoldings of the basal plasma membrane serve?
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In the respiratory system, cilia primarily function to:
In the respiratory system, cilia primarily function to:
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Which ion channels or pumps are particularly abundant in the basolateral domain of epithelia?
Which ion channels or pumps are particularly abundant in the basolateral domain of epithelia?
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Study Notes
Other Forms of Epithelium & Epithelial Cell Polarity
- Epithelial cells adapt structurally to specific functions
- Cell membrane specializations are correlated to their function
- Clinical disorders can be related to structural abnormalities in cell membranes
Specialized Forms of Covering Epithelium
- Special types of epithelium perform specialized functions
- Germinal epithelium differentiates into sperm (males) or ovum (females)
- Found in seminiferous tubules (testes) and ovaries
- Sensory epithelium contains sensory nerves
- Functions as sensory receptors
- Examples: taste buds, ear hair cells, retinal cells
Epithelial Cell Polarity
- Most epithelial cells exhibit structural changes in cell membranes
- This represents adaptation to specific functions
- Cell membranes have polarity, directed towards a surface
Apical Domain
- Refers to the part of the epithelial cell facing the lumen
- Functions in ion, molecule, and water transport
- Rich in ion channels, carrier proteins, ATPase, glycoproteins, hydrolytic enzymes, and aquaporins
- Contains microvilli with associated glycocalyx, and potentially stereocilia, cilia, and flagella
a. Microvilli
- Finger-like cytoplasmic projections on cell surface
- Increase surface area for absorption
- Contain microfilaments for rigidity
- Examples: striated border of intestinal cells and brush border of kidney proximal tubule cells.
b. Stereocilia
- Long, non-motile microvilli
- Found in the epididymis
- Increase surface area
c. Cilia
- Long, motile apical processes with rhythmic bending
- Composed of microtubules (9+2 arrangement)
- Contain dynein for energy
- Found in ciliated epithelia (respiratory system, oviduct)
Clinical Hint: Kartagener's Syndrome
- Hereditary defect in ciliary dynein
- Results in infertility and susceptibility to lung infections
II. Basolateral Domain
- Divided into lateral and basal plasma membranes
- Contains specialized features like receptors, ion channels, and constitutive secretion pathways
- Includes junctional specializations
a. Basal Enfolding
- Basal surface of some epithelia contains numerous infoldings
- Increases surface area, and partitions mitochondria-rich cytoplasm
- Important for ion transport
b. Hemidesmosomes
- Structurally similar to half-desmosomes
- Connect basal cell membrane to the basal lamina
- Keratin tonofilaments are attached to plaques within the cell
- Extracellular moieties of transmembrane linker proteins bind to laminin and type IV collagen in the lamina
c. Basal Lamina
- Lies between epithelium and underlying connective tissue
- Composed of adhesive glycoproteins, like laminin and collagen type IV
- Important for cell attachment and tissue integrity
Clinical Hint: Metaplasia
- Transformation of one type of epithelium into another
- Loss of function is possible
Glandular Epithelium
- Found in glands
- Classified by number of cells, duct presence/absence, duct branching, mode and type of secretion
- Endocrine glands secrete hormones directly into the blood
- Exocrine glands secrete into a cavity or onto a surface, have ducts
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Description
Explore the specialized forms of epithelium and the concepts of epithelial cell polarity in this quiz. Understand how structural adaptations enable epithelial cells to perform specific functions, and learn about the significance of the apical domain in epithelial cells. This quiz examines the connection between cell membrane structures and clinical disorders.
